Download Maintaining a Balance #7

Maintaining a Balance – Bio Notes
Outcome 1 – LEFT-HAND SIDE
Role of Enzymes
 Biological catalyst protein molecules that speed up chemical
reactions in living organisms
 Enzymes assist in the metabolism by increasing reaction rate of
the formation, breaking down and exchanging of molecules
 Body would not function without enzymes because these
chemical reactions could not occur at a necessary rate to
maintain body function
 Remain chemically unchanged prior to reaction
 Have an active site where substrate meets enzyme
 Binding of substrate molecule to enzyme, brings about
temporary induced change to shape of enzyme = induced fit
model
 The greater the substrate concentration, the greater the rate
of reaction until all active sites are occupied – saturation point
 Most work at maximum efficiency at 37 degrees Celsius and rate
of reaction decreases the further away from this temperature it
goes.
 Four fundamental features:
o Enzymes do not make a reaction occur that would not
occur on its own  they only make it happen faster
o The enzyme molecule is not permanently altered by the
reaction  A single enzyme can be used time and time
again to catalyze the same reaction
o An enzyme can catalyze a reaction both forwards and in
reverse
o Enzymes are highly specific for the substrate they bind to
 they can only catalyze one reaction
Identify pH as a way of describing the acidity of a substance
 pH is a way of describing the acidity of a substance
Explain why the maintenance of a constant internal environment is
important for optimal metabolic efficiency
 Metabolism is governed by enzymes
 When temperature and pH are not at optimum levels enzymes
are not able to perform at their optimum
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When temperature and pH diverge too far off their optimum
levels within an organism, enzymes begin to denature and change
shape permanently
This change in shape disallows the enzymes to perform the role
they had been assigned too  disallowing optimal metabolic
efficiency
They work at the optimum metabolic efficiency when internal
environment is constant and multi-cellular organisms regulate
their internal environments to remain healthy
Describe Homeostasis as the process by which organisms maintain a
relatively stable internal environment
 Homeostasis is the process by which the internal environment is
kept within normal limits regardless, of the external
environmental conditions.
 Conditions needing regulation include:
o Temperature
o pH
o Gas levels  oxygen and CO2
o Water
o Salt concentrations
o Sugars
o Nitrogenous wastes
 This allows the enzyme's optimal conditions to be met and the
body to work efficiently and kept as stable as possible.
2 Stages of Homeostasis
Detecting changes from the stable state
 Organisms pick up information from their external and internal
environments and react appropriately
 Information that provokes response = Stimulus
Stimulus – changes in…
Type of Receptor
Light
Photoreceptor
Temperature
Thermoreceptor
Sound, touch, pressure, gravity
Mechanoreceptor
Oxygen, Carbon Dioxide, water,
Chemoreceptor
pH, inorganic ions, nitrogenous
wastes, glucose
Electrical fields, magnetic fields
Other specialised receptors
 Organism have special receptors to detect the stimuli
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Counteracting Changes
 Once receptors have detected change a message is sent to the
appropriate control center where an effector is put into place
to counteract the change
 In mammals, effectors may take the form of muscles or glands
o Muscles contract or relax, bringing about movement in
the body e.g. shivering to maintain heat
o Glands secrete a chemical substance e.g. saliva glands
produce saliva when food is detected
Outline the role of the nervous system in detecting and responding to
environmental changes
 The nervous system, along with the endocrine system, carries
the afferent and efferent messages to and from the control
center during a negative feedback response
 Endocrine system produces hormones, made in specified glands
and transported in the blood to the areas where their effectors
will bring about a response
 Nervous system maintains and regulates an animals internal
environment and respond to changes in the external
environment
 The nervous system consists of the central nervous system
(CNS) and the peripheral nervous system (PNS).
 The CNS consists of the brain and spinal cord
 The PNS consists of the sensory nerves and the effector
nerves.
 When the environmental temperature begins to exceed a
comfortable level for the body:
o Temperature sensors in the skin detect the temperature
change
o A sensory neuron conducts a nervous impulse to the
hypothalamus found in the brain
o Nerve impulses pass this information from the receptors
to effector neurons
o Then onto effectors, such as blood vessels, sweat glands,
endocrine glands and muscles.
Identify the broad range of temperatures over which life is found
compared with the narrow limits for individual species
 Temperature of an environment = ambient temperature
 Most life on earth lives in temperatures between 0-45 degrees
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Exceptions found in -70 and up to 200 degrees at the poles and
in black smokers in oceanic trenches
Individual species, however, have much narrower temperature
bands within which they can survive (eg humans can only survive
unclothed and unsheltered from 27°C to 43°C)
Below 0oC, cells risk ice crystals forming in them and above
45oC, proteins within cells may denature.
Compare responses of named Australian
Ectothermic and endothermic organisms to
Endotherm
changes in the ambient temperature and explain
how these responses assist temperature
Ectotherm
Body
regulation
Temperature
Endotherms
 Birds and mammals are endotherms.
Environmental
Temperature
 Body metabolism generates heat and
maintains an internal body temperature
that is independant of the external temperature.
 They require more food intake to provide for the energy used
up during this process
 Red Kangaroo  Homeostatic temperature of 36C
 Behavioural
o Seeks the shade of rock crevasses and caves on hot days
 to stay cool by minimising exposure to sunlight
o Licks its forelimbs where the blood vessels run close to
the surface and heat is lost from the body and by wetting
the surface with saliva, evaporation occurs promoting loss
of heat from blood
o Stands in the shade, tucks its tail under it and allow air to
circulate around.
 Structural
o Has a layer of fur providing insulation in cooler seasons
o Spring like Achilles tendon recycling energy with every
bound  more efficient at high speeds
 Physiological
o Changes bodily heat flow to not allow heat to the
extremities of it's body in order to conserve heat
o Shivers when cold
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Ectotherms
 Organisms which rely on behavioural adaptation to regulate
their body temperature through the environment
 E.g. plants, all invertebrates, fish, amphibians and reptiles
 Body temperature rises and falls with ambient temperature
 Aquatic ectotherms remain at temperature of the surrounding
water, they do not show any specialised adaptations to regulate
their body temperature
 Terrestrial ectotherms and endotherms experience a greater
range of temperature changes and have receptors
(thermoreceptors) to detect these changes and respond
respectively
 Behavioural adaptations to temperature change:
o Migration
o Hibernation
o Shelter
o Nocturnal activity
o Controlling exposure
 Crocodile  ideal temperature of 31-32 degrees
Plant
Beech Tree
Response
Deciduous  leaves
drop in winter
Daffodil
Plant dies back leaving
no parts above the
ground
Geraniums
Plant produces smaller
leaves to reduce
surface area exposed
to heat
Mulga tree
Thick silvery cuticle
around leaves
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Benefit
Reduces growth rate
 less energy needed
and avoids damage to
leaves
Bulb is protected
underground allowing
it to survive winter
and it will sprout again
when weather is more
favourable
Creating less stomates
 disallowing
increased transpiration
which causes plant to
dry out
Reflects sunlight 
less evaporation/water
loss and protects
against over heating
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o Orientate themselves so their maximum body surface is
exposed to the sun in order to warm themselves
o Arrange themselves so their relatively small head receives
minimal heat while the body continues to heat
o Open their mouths allowing the brain to cool through
evaporation
o When in the water  they move around the environment
to find cooler or warmer areas varying on the necessary
temperature
o In extreme cold they dig burrows under water
o In extreme heat, they remain in the water in order to
prevent dehydration.
Identify some responses of plants to temperature change
 Respond to change by altering growth rate – hence seasonal
growth
 In extreme weather, many plants may die but leave dormant
seeds with thick protective layer
 Alternatively, some die above ground, leaving roots, rhizomes,
bulbs or tubers to survive underground – these then sprout
again when conditions are favourable
 Vernalisation: exposure to cold conditions that some plants
require before they can develop flowers
Outcome 2 – RIGHT-HAND SIDE
Test the effect of increased temperature, change in pH, and change
in substrate concentrations on the activity of named enzymes
 Increased temperature: Gelatine as substrate, pineapple juice as
enzyme – heat juice
 Change in pH: as above – mix juice with equal volume of vinegar
 Change in substrate concentrations on the activity of named
enzymes: same as above - add more jelly
 All leads to less breakdown of the jelly
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Milk procedure:
Change in temperature
 Make a rennin solution by dissolving a junket tablet in distilled
water
 Add the same amount of rennin solution to a number of test
tubes of milk, eg 7 test tubes
 Place test tubes in different water baths at temperature ranges
such as 0oC, 10oC, 20oC, 30oC, 40oC, 50oC and 60oC. Make sure
each water bath is kept at the temperature it has been
allocated
 Time the interval between adding the rennin and curdling of the
milk for each temperature
 Note that the variables kept constant in each test tube are the
junket solution, the pH of the solution, the type of milk and
the quantity of milk in each test tube
Change in pH:
 Make a rennin solution the same as was done in the previous
and add hydrochloric acid of various concentrations and with
known pH levels each into a different solution, labeling each
with pH level
 Add the same amount of rennin solution with the varying pH to
six test tubes of milk
 Place in a water bath kept at a constant temperature of 37oC
 Time the interval between adding the rennin and curdling of the
milk in each test tube
 Note that the variables kept constant in each test tube are the
junket solution, the type of milk, the temperature of 37oC, and
the quantity of milk in each test tube.
Change in substrate concentration:
 Make different concentrations of the substrate by diluting the
milk using different amounts of powdered milk to get different
concentrations  equal amounts of liquid with different and
noted milk concentration
 Add the same amount of rennin solution to each test tube of
milk
 Place in a water bath kept at a constant temperature of 37oC
 Time the interval between adding the rennin and curdling of the
milk
 Note that the variables kept constant in each test tube are the
type of milk, the temperature of 37oC, and the quantity of milk
in each test tube.
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Develop a model and a feedback mechanism
Outcome 2 – LEFT-HAND SIDE
Identify the forms in which each of the following is carried around
mammalian blood:
Substance
Carbon Dioxide
Oxygen
Water
Salts
Lipids
Nitrogenous
Waste
Other Products
of Digestion
Form
Mainly as hydrogen carbonate ions, some as
carbaminohaemoglobin, some dissolved in the
plasma
Attaches itself to haemoglobin 
Oxyhaemoglobin
Water molecules
Dissolved ions in the plasma
With phospholipids and cholesterol in a protein
coated package  Chylomicrons
Urea, uric acid and creatinine  dissolved in
blood plasma
As separate molecules e.g. glucose, amino acids
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Carried By
Red blood cells and plasma
Red blood cells
Plasma (makes up 90% of
plasma)
Plasma
Lymph and plasma
Plasma
Plasma
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Explain the adaptive advantage of Haemoglobin
Structure:
 Composed of 4 haem units forming a complexing protein 
globin
 Each haem unit is a ring structure with iron in the center
allowing it to bind to oxygen  forming oxyhaemoglobin
 Each red blood cell can carry 280 million haemoglobin molecules
Function of Haemoglobin
 Transports of Oxygen to body cells from lungs
 Transports of some Carbon Dioxide from body cells to lungs –
Carbaminohaemoglobin
 Conversion of some Carbon Dioxide to hydrogen carbonate ions
via enzyme carbonic anhydrase
 Produces hydrogen ions – separates acid
 Buffering of the hydrogen ions – for protection
 Major role of Hb is transport of Oxygen
o Oxygen is not very soluble in water
o Most is carried by Hb
o Interaction of iron ions with oxygen binds oxygen to Hb –
Oxyhaemoglobin
o This occurs when pressure (concentration) of oxygen is
very high e.g in lungs
o Bond is broken when oxygen pressure (concentration) is
low e.g. in body cells
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Adaptive Advantages of Hb
 Oxygen is minimally soluble in water which makes up 90% of
blood plasma
 Therefore it carries majority of the oxygen around the body
allowing respiration to take place
 These organisms are then far more efficient and effective
operators of their environment than their anaerobic
competitors
 Hb molecules unload very quickly in tissues when oxygen is low
and bind very quickly when oxygen is high
 This is due to the increase in ease with which the 2nd, 3rd and 4th
molecules are loaded/unloaded after 1st
 Relates to temperature: at low temperatures, when more energy
is required to sustain body temperature, graph becomes more
upright – quicker and vice versa
 Relates to pH: decrease in pH changes shape of molecule to
release oxygen more easily because the lowered pH will
decrease Oxygen saturation
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Compare the structures of arteries, capillaries, and veins in relation to
their function
Vessel
Artery
Diagram
Vein
Capillary
How the structure relates to function
- Carries blood from heart to body
- Three tissue layers: endothelium as a lining,
smooth muscle to contract the vessel and
connective tissue to allow for expansion
- Small diameter, thick walled, elastic and
muscular to withstand high pressure
- The elastic fibres maintain blood pressure and
send blood in spurts towards body tissues via
the vessels expanding and recoiling with
heartbeat
- Carries blood back to heart after passing
through the capillaries
- Thinner walls, less muscle and larger diameter
than of arteries as blood flows at a lower
pressure
- One-way valves and surrounding muscles keep
blood flowing in a single direction
- Single, thin endothelium layer  large surface
area  to allow for a faster rate of diffusion of
nutrients in and out of the capillary to
surrounding cells
- Diameter of a single cell
- Surround tissues cells so that no cell is too far
from a capillary to receive nutrients
Describe the main changes in the chemical composition of the blood
as it moves around the body and identify tissues in which these
changes occur
 Blood flows through two systems:
 Pulmonary
o Pulmonary system serves to increase levels of Oxygen and
decrease levels of CO2
o Blood flows from heart to lungs and back to heart again
o Blood travels in the pulmonary artery from the right
ventricle to the lungs where carbon dioxide is released
into the alveoli of the lungs  and then released out of
the body
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o Oxygen is picked up from the alveoli and diffused into the
red blood cells to then be taken back to the heart
 Systemic
o Blood flows from the heart to the rest of the body,
except the lungs, and then back to the heart again
o Blood flows under high pressure out of the left ventricle
and some fluid is forced out of the blood to become part
of the body fluid
o The left ventricle pumps oxygenated blood to the rest of
the body, and as this blood circulates in capillaries, oxygen
is delivered to the cells and carbon dioxide is picked up
o Any ions or nutrients (e.g. glucose for respiration)
required by cells also leave the blood and waste products
of metabolism (urea, CO2) enter the blood
o Other waste products, such as urea, are also picked up
from the liver and transported in the blood to the kidneys
o Blood flowing through the
kidneys loses it's urea and
has it's water and salt
composition balanced
o Blood flowing to the small
intestines collects the
products of digestion (e.g
glucose and amino acids) and
transports them to the liver
 where the level of many
circulating substances is
controlled
o Deoxygenated blood returns
to the heart via the inferior
and superior vena cava
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Outline the need for oxygen in living cells and explain the removal of
carbon dioxide from cells is essential
 Oxygen is necessary for Cellular Respiration – process by which
cells obtain energy from glucose
 Oxygen combines with glucose in a sequence of enzyme
controlled steps during cellular respiration to release chemical
energy as ATP, the chemical energy needed by cells for their
metabolism
 Glucose + Oxygen  Carbon Dioxide + Water + Energy (in form
of ATP)
 Although glucose and other food molecules are energy rich,
energy stored in them must be converted into a form that living
cells can use for metabolism
 Carbon Dioxide is produced in cells as a waste product of
chemical respiration
 When CO2 reacts with water (in the cytoplasm of cells or in the
plasma of blood), it forms carbonic acid
 Build up of carbonic acid is toxic as it lowers the pH of the cell
and bloodstream, affecting homeostatic balance
 A low pH would prevent enzymes from functioning optimally and
this affects cell functioning by reducing metabolic efficiency in
the body
 Therefore the removal of CO2 must be removed to prevent a
lowering of the pH in the body cells to ensure an optimal
environment for enzyme function is maintained
Describe current theories about processes responsible for the
movement of materials through plants in xylem and phloem tissue
Xylem  transport of water and dissolved minerals
 Structure
o No nucleus
o No air spaces
o Vessels
 Cells placed on top of another with the cross wall
removed
 Dead, hollow tubes
 Have pits and cross walls are perforated
 Provide support
 Supply water via transpiration pull
o Tracheids
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Still have cross-walls  not perforated; their ends are
tapered so they meet up with each other
 Primary wall: first wall of cellulose
 Secondary wall: inside primary wall  thickens xylem to
strengthen  deposited in particular patterns e.g.
rings, spirals, just around pits, reticulate (not a full
wall, just a reinforcement)
o Pits:
 Allow for bypassing of blocked vessels
 Transport
o Water only goes upwards
o If there is a blockage it moves through a pit and
continues to go upwards
o Pulled by Transpiration pull  brings minerals into water
via cohesion of water molecules
o Root pressure pushes water up to start
o Capillarity  water adheres to cell walls and each
molecules adheres to the one before it and transpiration
pull brings it up
o Large surface are to volume ration allows water to adhere
to cell walls and travel further up with less activity 
capillarity (capillaries are very thin)
Phloem  transport of organic materials (water and glucose)
 Structure
o Consists of phloem parenchyma
o Sieve tube cells (either side of the sieve tube element) 
Cytoplast in strands through sieve tube elements
o Companion cells (take nucleus)
 Transport
o Travels in two directions at different times
o In summer when extra glucose is made, it can either be
stored as starch in the mesophyll OR it is moved
downward by translocation in the phloem from the
source (chlorenchyma in either palisade or spongy
mesophyll) down o the sink in the cortex of the root and
is stored there
o In spring, when most growth takes place, the nutrients
that has been stored in the roots (now the source) and is
moved upwards by translocation, to the growing points of
the plant

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1. Glucose is actively taken from the leaves
into the phloem because there is already
a higher level of glucose in the phloem
2. Water (from xylem) will then passively
follow the glucose into the phloem
creating a high-pressure system
3. This then is moved downwards by
translocation, towards the roots and
glucose is actively removed from the
water and taken into the cortex for
storage and converted into starch
4. Water then flows back up to the xylem
creating a low-pressure system at the
roots because the water is leaving the
root
5. There is a high-pressure system at the
top (the source) because water is entering phloem there so
water is now able to passively flow from high to low pressure
points, transporting dissolved glucose with it
 In spring the roles change and the roots become the source and
the growing point become the sink but the same process occurs
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Outcome 2 – RIGHT-HAND SIDE
Demonstrate the effect of dissolved carbon dioxide on the pH of
water
Method
1. Blow through a straw into a beaker of lime water for 30
seconds
2. Blow through a straw into a beaker of water with 3 drops of
universal indicator for 30 seconds
3. Record any observations in colour change
Results and Conclusion
Chemical
Colour change
Limewate Colourless 
r
cloudy
Universal
Green  yellow
Indicator

The fact that the limewater went cloudy indicated that
carbon dioxide was present
 The fact that the universal indicator turned yellow indicates
that the carbon dioxide turns water acidic
Use a light-microscope, and prepared slides to gather information to
estimate the size of red and white blood cells and draw scaled
diagrams of each
REMEMBER: 1 micrometer = 1000 millimeters
RBC
1. Use a grid slide divided into mm2 that has one mm square
further divided into 10 equal squares
2. Under low power (100x) count the number of grids across the
diameter of the field of view to approximately 1 decimal place if
need be
3. Example diameter of the LP field view might be 1.5 mm, which is
1500 μm
4. Noting this diameter, place a prepared blood slide under LP
5. Count approximately how many RBC’s fit across the diameter of
the field view  there will be a level of estimation in this count
6. Move microscope to high power (400x) and count again to
double check (you should count around a quarter of those that
u counted on LP)
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Page 16 of 37
7. Take the diameter of the field view (1500 μm) and divide it by
the number of RBC’s you counted across the diameter of your
field view under LP
8. This is the approximate size of one RBC (probably between 6–
8 μm)
9. Draw these cells out, dispersed as you see them, according to
the scale you have concluded on
WBC
10. Look through the field view to find a WBC (larger cells with
clearly defined and stained nuclei)
11.Either under LP or HP examine a WBC that is placed close to a
few RBC and compare the size of the two
12. By comparing them, make an estimation as to the size of the
WBC
13.WBCs should be almost double the size of RBCs so the
approximate size would be 12–15 μm
o Cannot use the same method as for the RBC because
there are not enough WBCs in blood to be able to cover
the diameter of a field view in a single sample slide
14. Draw the WBC according to the same scale as done with the
RBC
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Technologies that allow measurement of oxygen saturation and
carbon dioxide concentrations in blood and describe and explain the
conditions under which these technologies are used
 Arterial Blood Gas (ABG) Analysis
o Takes blood samples from artery
o Tested in Blood Gas Analyser for concentration of oxygen
and concentration of CO2 and pH
o When moving through a membrane, oxygen in the blood
produces an electrical current while carbon dioxide
changes the pH of the solution
o Oxygen is measured according to magnitude of electric
current present
o CO2 measure according to the pH level
o Invasive procedure
o Delay between sampling and results
o Provides vital info for critically ill patients – on ventilators
or undergoing respiratory therapy
 Pulse Oximetry
o A pulse oximeter receive information of light absorption
transmitted to it by a connected clip that has a sensor in
it
o The sensor emits a light signal that passes through the
skin
o The colour of blood changes depending on it oxygen
concentration
o Measures absorption of light as light passes through the
finger, ear-lobe, or toe, from light source to the
photodetector (on either end of the clip)
o This information is transmitted to the pulse oximeter and
present in percentage form
o Reading can be variable on dark skin or dark nail polish
o Non-invasive
o Rapid, continual monitoring of arterial blood
 Capnometry
o Capnometer measures concentrations of respired gases
using infrared light beam
o Air is exhaled it capnometer which holds an infrared light
source
o The amount of light absorbed by the infrared beam
depends on number of carbon dioxide molecules present
o Samples measured often and very accurately
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o Capnography is a more detailed form of this, giving a
waveform display of CO2 concentrations over time
showing dividing up different points of the respiratory
cycle
o Non-invasive
o Monitors changes in carbon dioxide concentrations
continuously
o Can be used when patients oxygen levels are stable
therefore having no need to have oxygen monitored
Identify products extracted from donated blood and discuss the uses
of these products
Cellular:
 Platelets: used for control of hemorrhage in patients whose
platelets have become defective or deficient e.g. leukemia
 Red Blood Cells: ideal for replacement of red blood cells lost
during an emergency or surgery
 White Blood cells: occasionally used for patients who are not
producing their own white cells or who have very low white cell
counts and have serious bacterial infections
Non-cellular
 Intragram: Used to reduce susceptibility to infections and
manage many immune system diseases e.g. after bone marrow
transplants/chemotherapy
 Factor VIII: management of haemophilia
 Immunoglobin: Temporary prevention of measles, rubella and
hep. A
Report on progress in the production of artificial blood and use
available evidence to propose reasons why such research is needed
 Not actually blood, just an oxygen-carrier
 Does not includes other proteins e.g. clotting proteins and
hormones
 Designed only to carry oxygen and carbon dioxide
 Free of infectious agents and allergens (non-toxic and disease
free)
 No need to refrigerate and can be kept for more than a year,
unlike human blood with life-span of 3 weeks
 Accepted by all blood groups allowing transfusion without
testing  artificial blood as no foreign markers
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Page 19 of 37
Readily available in large supplies
Some people have religious objections to receiving blood
transfusions e.g. jehova’s witnesses  artificial blood is
regarded as medicine rather than transfusions therefore
allowing an alternative method of healing patients
 One cannot live off artificial blood, only serves to restore blood
volume
 2 types of oxygen carriers:
 Perfluorocarbon-based e.g. oxycyte and flurovent
o Most promising form
o Easily dissolves oxygen and transports
o Non-toxic as products, compatible with body and can be
broken down by body
o Cheap to produce
o Because of it’s chemical nature there is no genes  no
need to tissue match
o Does not contain any biological contaminants
o Combined with other materials e.g. lipids to form emulsion
and injected into patient
o Uses: surgery, trauma, oxygenation of tumours doing
radiation, following major disaster
 Haemoglobin-based blood substitutes
o Using haemoglobin from other animals e.g. cattle etc
o Red blood cells from other animals are broken open and
Haemoglobin is removed
o Haemoglobin is then mixed with carrier compounds to
form emulsion and injected
o Effective oxygen carrier
o No cell wall  no markers to be detected as foreign by the
body
o Could contain chemicals
o Problem: Haemoglobin, because of lack of protective
membrane, it is vulnerable to degradation, which is toxic
to the body  cannot be used
o Clinical trial ongoing and research continuing
o Trying to make the molecule more stable to prevents its
degradation by increasing bonds within the molecule
 Future directions  new methods of forming haemoglobin being
developed e.g. by synthesis (in bacteria plasmid) or recombinant
DNA technology text pg. 183


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Page 20 of 37
 Blood volume is restored via a drip of normal saline mixture as
per plasma, to replace plasma volume  haemoglobin is added
to this normal saline
 Normal saline increases blood pressure to maintain pressure in
glomerulus to avoid kidney failure  but does not transport
oxygen
Draw transverse and longitudinal section of phloem and xylem
Outcome 3 – LEFT-HAND SIDE
Explain why the concentration of water in cells should be maintained
within a narrow range for optimal function
 Water maintains cell shape  too little or too much can cause
cell to shrivel or burst
 Water is the solvent for metabolic reactions in living cells
 Many molecules and all ions important for the life of the cell are
carried in an aqueous solution and these diffuse to reaction
sites through the water in the cell
 Water is the solvent in which most substances dissolve and is
the transport medium for distributing them
 It is critical for proper functioning of these reactions  the
amount and concentration of water in the cell be kept
constant
 Changes in the concentration of water will usually be
accompanied by changes in the concentration of solutes
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 E.g. a decrease in water concentration leads to an effective
increase in carbon dioxide concentration  which decreases
the pH  which hinders the functioning of enzymes
 Living cells work best in an isotonic environment (where solute
concentration is the same both inside and outside the cell)
 They are very sensitive to changes in solute concentration and
may lose or take in large amounts of water – can cause death of
the cell
 In large terrestrial mammals such as humans, the interstitial
fluid that bathes their cells is kept isotonic to the internal
solute concentration of the cells
Explain why the removal of wastes is essential for continued metabolic
activity
 Wastes from metabolic processes can be toxic to cells by
slowing metabolism or poisoning cells
 E.g. CO2 (from respiration) can change the pH of cells and
hinder the function of enzymes
 Even the accumulation of non-toxic wastes can be dangerous
because increased concentration of products can interfere
with reaction rates
o Metabolic wastes are the product of metabolic reactions
 If they are not removed their concentration in the cell
increases  inhibiting the reactions that produce them,
interfering with normal metabolic activity
 Nitrogenous wastes have the ability to change the pH of cells
and interfere with membrane transport functions and may
denature enzymes
 Ammonia is highly toxic and needs to be removed as quickly as
possible or converted into a less harmful form
 Ammonia increases pH to make the fluid in cells and tissues
basic
 There is a correlation between the type of wastes produced and
the animals environment
o Aquatic animals: excrete mostly ammonia (can be
excreted directly into water as it is highly soluble)
o Land animals: Conserve water but converting ammonia
into less toxic forms so they can hold it for longer in the
body and excrete it periodically
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Identify the role of the kidney in the excretory system of fish and
mammals
Fish
 Primary role is osmoregulation – the regulation of the salt and
water concentrations in the body
 Excretion of nitrogenous waste products (ammonia) occurs
across the gills
 The kidneys adjust the levels of water and mineral ions in the
fish’s body in order to maintain a constant concentration of
internal fluid for the cells
 Freshwater Fish:
o Bony fish living in fresh water maintain a higher
concentration of solutes in their body than the
concentration in the water outside – hypertonic to their
surroundings
o Water therefore tends to diffuse into the body and so the
fish need to continually rid of the excess
o Their kidneys produce copious amounts of very dilute
urine in an almost continuous stream in order to achieve
this
o As fresh water has a lower concentration of ions than the
fish do, the kidneys actively reabsorb salts to prevent
their loss
 Saltwater Fish:
o Bony saltwater fish have the opposite problem – their
internal body fluids are less concentrated than the
surrounding water
o To avoid water loss from their body, mine fish keep
drinking salt water
o They absorb the water and salts
o The water is retained and the salts actively excreted,
some via the gills and some via the kidneys  salt water
bone fish excrete very little urine
o Marine cartilaginous fish (sharks and rays) have their
tissues isotonic with the sea water so there is no net
movement of water in or out  avoiding osmoregulation
problems of bony fish
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Mammals
 Regulate the internal salt and water concentrations in the blood
 Excrete urea, the nitrogenous waste produced by mammals
 Maintains precise balance between waste disposal and needed
salt and water concentrations
 Deamination
o Proteins are made from amino acids  they are made,
used and broken down in cell metabolism
o Mammals are unable to store amino acids so excess
becomes nitrogenous waste to be removed
o These excess amino acids are transported to the liver
where they are broken down in a process called
deamination  this involves removing the part containing
a nitrogen to form urea
o The remainder is converted to a carbohydrate which may
be stored or used immediately
o Urea is transported by the blood to the kidneys and
excreted in the urine
Explain why the process of diffusion and osmosis are inadequate in
removing dissolved nitrogenous wastes in some organisms
 Diffusion and osmosis are both examples of passive transport
relying on random movement
 They will not occur unless a sufficient concentration gradient is
present
 Diffusion is a slow process and non selective of solutes
(therefore not useful for nitrogenous wastes)
o All salts would be eliminated along with glucose and
vitamins whereas the body needs to retain some salts and
nutrients
o Urine concentration in the collecting tube could never be
greater than that in the blood vessels running into it, so
the urine would be too dilute and too much water would
be lost
 Osmosis deals with the movement of water across a semi
permeable membrane and not wastes
o Nitrogenous wastes would remain in the body and water
would leave it
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Distinguish between active and passive transport and relate these to
processes occurring in the mammalian kidney
 Passive movement  requires no energy from the cells since
molecules move along a concentration gradient (from high to
low gradient)
o Diffusion: the movement of molecules from high to low
concentration
o Facilitated diffusion: movement of molecules using carrier
protein molecules to transport them across the cell
membrane
o Osmosis: movement of water molecules across a cell
membrane
o Filtration: movement of water and other particles across a
cell membrane caused by blood pressure
o Limitations: it depends on the presence of a difference in
concentration of substances (a concentration gradient)
o It is also relatively slow (especially without a steep
concentration gradient)
 Active transport uses energy to pump or carry materials across
the membrane
o Specific carrier proteins may bind with the substance and
carry it through the membrane
o Endocytosis is another type of active transport  involves
the formation of a pouch that carries the matter through
the membrane
Within the kidney
 Passive transport:
o Filtration of blood occurring under the high blood
pressure conditions of the Bowman’s capsule
o The movement of some nutrients and hydrogen ions out
of proximal tubule
o Water moving via osmosis in to the blood from the
descending limb of the loop of henle
o Some salt excreted from the ascending limb
o Some water transported into blood from distal tubule
o Water transported into blood from collecting duct
 Active transport:
o Nutrients and salt transported into blood from proximal
tubule
o Drug poisons transported into proximal tubule from blood
o Salt transported into blood from ascending limb
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o Salt, hydrogen carbonate transported into blood from
distal tubule
o Potassium and hydrogen ions transported into distal
tubule from blood
Explain how the processes of filtration and reabsorption in the
mammalian nephron regulate body fluid composition
 Each kidney is made up of about one million small filtering units
called nephrons  in these structures, urine is produced
 There are three processes in the formation of urine: filtration,
reabsoption and secretion
 Passive transport occurs in filtration and in the osmosis of
water back into the blood
 Active transport occurs in the secretion of substances into the
nephron, the active transport of nutrients back into the blood
and the selective reabsoption of salts required by the body
 Filtration:
o Commonly occurs throughout the entire nephron system
especially within the Glomerulus and Bowman's Capsule
where water, nitrogenous wastes, glucose, amino acids,
vitamins, minerals, bicarbonate ions and hormones.
o The large amount of plasma that also comes through the
Glomerulus is due to the extremely high blood pressure
present within this structure
o This pressure forces fluids and dissolved substances
through walls of the glomerular capillaries  into the
Bowman’s capsule
o The pressure is so high in to glomerulus that some of the
liquid from the blood is forced through the walls of the
glomerulus into the Bowman’s capsule  glomerular
filtrate
o Water, urea, ions, glucose, amino acids and vitamins are all
small enough to be moved into the glomerular filtrate
o Blood cells and proteins are too large to be removed
o Filtration is a non-selective passive process  many
valuable components of the blood must be recovered by
reabsorption
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 Reabsorption:
o Occurs in the tubules
o Water, salt and nutrients move by active transport from
the tubule into the surrounding capillaries
o Controls concentration of substances in body fluid e.g.
some amino acids, glucose, vitamins, some water, and some
salts are reabsorbed
o Proximal tubule: active reabsorption of salts and
nutrients e.g. glucose, Amino Acids and Potassium Ions
o Movement of salt actively out of tubules causes water to
follow passively
o Most bicarbonate ions are reabsorbed here to maintain
the constant pH of the blood and body fluids
o Loop of Henle: the descending limb allows for the
reabsorption of water through osmosis
o The ascending limb allows for the passive and active
transport of salts such as sodium to move out of the
tubules and be reabsorbed
o Distal tubule: Selective reabsorption to adjust the pH of
the blood and level of salts
o Walls are permeable to water but not salt  water passes
out by osmosis
o Collecting duct: Water may be reabsorbed here but the
amount is dependent on the body’s need at the time
 Secretion: A selective process by which the body actively
transports substances from the blood into the nephron
o Excess ions and chemicals such as drugs or poisons are
secreted
o Occurs in proximal and distal tubules
 Excretion: Excess water and solute are eliminated in the form
of urine
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Outline the role of the hormones, aldosterone and ADH (anti-diuretic
hormone) in the regulation of water and salt levels in the blood
 Hormones are chemical messengers that travel in the blood 
they reach all parts of the body through the blood, but only
certain target cells in organs respond to each hormone
 Aldosterone: hormone controlling reabsorption of salts (i.e.
sodium ions  regulating blood pressure and volume
o Produced by the adrenal glands, situated above the
kidneys
o If there is a decreased blood volume and blood pressure
(resulting from low salt concentrations, which causes
water to be released) the output of the aldosterone is
increased
o Causes tubules to increase the reabsorption of sodium
ions and decrease the reabsorption of potassium
o When sodium ions re-enter the blood water follows by
osmosis, and chloride by diffusion and so
o Results in rise in blood pressure and volume
o Less water and salts will be lost in urine
o If the body has too much salt, the opposite occurs 
water is retained, the adrenals release less aldosterone
and salt remains in the tubules
 Antidiuretic hormone (ADH): hormone controlling reabsorption
of water  regulating urine concentration and blood volume
o It is made in the hypothalamus gland but stored in and
released from the pituitary gland in the brain
o Osmoreceptor cells in the hypothalamus monitor the
concentration of blood
o If there has been water loss from the body (from sweating
etc), the blood is more concentrated than normal ADH is
released into the blood and circulates to the kidneys
o ADH increases the permeability of the walls of the
collecting ducts to water
o In the presence of ADH, water passes freely by osmosis
out of the ducts back into the body
o As the blood returns to normal concentration by negative
feedback, less ADH is secreted
o If blood concentration is low (eg. Drinking a lot of water)
very little ADH is released.
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o The permeability of the collecting duct walls is decreased,
less water is reabsorbed and more is passed out with the
urine
o Increased salt results in water retention  controlled by
ADH  reduces the concentration but not the total
amount of salt which is regulated by aldosterone
Enantiostasis and its importance to estuarine organisms in
maintaining appropriate salt concentrations
 Enantiostasis: the maintenance of metabolic and physiological
functions in response to variations in the environment
 It causes compensatory change in the internal environment
counteracting changes in external environment
 It is therefore less costly than homeostasis
o Involves some physiological or compensatory change
o Allows organism to tolerate extreme external environment
change
o Internal environment will change significantly
o External environmental changes are extreme
 Estuarine organisms e.g. the blue crab
o All estuarine organisms, experience large changes in salt
concentration in their environment over a relatively short
time span due to the tidal movement and mixing of fresh
and salt water
o Organisms that must tolerate wide fluctuations of salinity
are said to be euryhaline o One strategy to withstand such changes in salt
concentration is to allow the body's osmotic pressure to
vary with that of the environment
 Organisms that do this, and therefore do not
maintain homeostasis, are said to be
osmoconformers
o Most marine invertebrates are osmoconformers
o However, as the salt concentration of body fluids in an
osmoconformer changes, various body functions are
affected, such as the activity of enzymes
o For normal functioning to be maintained, another body
function must be changed in a way that compensates for
the change in enzyme activity
o E.g. when a change in salt concentration in the body fluid
 which reduces the efficiency of an enzyme  is
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Page 29 of 37
compensated for by a change in pH  which increases
the efficiency of the same enzyme
 Halophytes e.g. Mangrove
o Plants adapted to living in salty environments
o 3 main methods of controlling salt levels
o Salt excluders: prevents entry of salt into root system by
filtration  passive and relies on transpiration
o Salt excreters: have special glands, usually in the leaves,
where salt is concentrated and then actively secreted
from plant  rain then washes the salt off
o Salt accumulators: concentrate or accumulate salt in a
part of the plant, usually the bark or older leaves, which
are then shed from the plant
Describe adaptations of terrestrial Australian plants that assist in
minimising water loss
 Xerophytes are plants adapted to arid regions where there is
little water available and the temperatures reach a high daily
maximum

Name of
Response / Adaptation
Benefit
Plant
Eucalyptus
- Leaves hang vertically in
- Tilted leaf ensure minimal heat
midday sun
absorption and water loss due to
- Thick layer in leaves
transpiration
(waterproof)
- Waterproof leaves and sunken
- Sunken and fewer
stomates also prevent water los due to
stomates
transpiration
Hakea
- Hard leathery, needle- Minimise water-loss due transpiration
(needlebush)
shaped leaves with
- Provides opportunity for reabsorption
reduced surface areas
- Sunken and fewer
stomates
Desert
- Reduced SA leaves
- Decreases water loss from
Plant
(cylindrical)
transpiration
- Stomates open during the
- Reduces area for absorption of solar
hottest part of the day
radiation  reducing transpiration,
therefore heat loss
Acacia
- Use of phyllodes rather
- Phyllodes, unlike leaves, do not lose
than leaves for
water in transpiration
photosynthesis
- Small or highly dissected leaves lose
- Small bipinnate leaves
heat far quicker than large leaves
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Structure of the mammalian kidney by dissection, and use a model or
visual resource to identify the regions involved in the excretion of
waste products
Risk Assessment
Hazard
Glass slides may break
and cut someone
Microscope may fall
off bench onto
someone’s foot
Scalpel may cut
someone
Scissors may cut
someone
Consequence
Leads to blood loss
and infection of
wounds
Could break or
seriously damage foot
Precaution
Handle with care and have proper glass
disposal facility available
Leads to blood loss
and infection of
wounds
Leads to loss of blood
and infection of
wounds
Handel with great care and immediately
identify authority if this should happen
Keep microscope at a safe distance
from the edge of the bench
Handel with great care and immediately
identify an authority should this happen
Method:
1. Place kidney on the dissecting tray and try to locate and gently
separate the three tubes at the concave surface of the kidney
2. Draw and label an external side view of the kidney
3. Use a scalpel to cut a median longitudinal section of the kidney,
starting at the convex surface. Do not cut the tubes and leave
the two halves of the kidney attached to them
4. Draw the internal structure of the kidney and label the
structure, noting the dark outer cortex, containing thousands
of nephrons and their associated blood capillaries, the lighter
and striped medulla and its many tubules, the hollow pelvis in
the concave part of the kidney, and the opening to the ureter
5. Insert a probe into the opening to the ureter, the hole at the
centre of the pelvis, to observe where it ends
6. Under the microscope, observe a prepared slide of kidney tissue
from the cortex and locate the filtration units of the neprhons,
identify the Bowman’s capsule and the glomerulus
7. Make your own labeled diagram of the image observed under
the microscope
LONGITUDINAL SECTION OF
KIDNEY
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MICROSCOPIC STRUCTURE
Macroscopic
Component
Ureter
Capsule
Cortex
Function
Urine to the bladder
Outer protective coating
Where glomerulus is located
Medulla
Made up of thousands of pyramids
made up by collecting ducts
Urine accumulates here before moving
down to the bladder
Microscopic
Function
Filtration unit
Pelvis
Component
Nephron
Malpighian
Body
Bowman’s
Capsule
Form the blood filtrate
Glomerulus
Knot of capillaries under high
pressure, filtering blood that enters
due to extreme pressure
Filter for molecules filtering out of
glomerulus, sending them into the
proximal tubule and holding back
blood proteins
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Structure
Outer cortex is darker due to intensity
of vascularisations
More stripey – tubules here
Structure
Malpighian body  proximal convulsion
 loop of Henle  distal convolutions
Combination of Bowman’s Capsule and
Glomerulus
Thin and porous to filter through small
molecules but NOT blood proteins
capillaries are distanced from BC wall
by pillars to allow particles to move
through capillary and then through BC
without the pores of the two having to
lining up
Wider afferent and thinner efferent
vessels causes pressure build up–
filtration process e.g. water, salt
molecules NOT blood proteins
Page 32 of 37
Proximal
tubule
Loop of
Henle
Distal tubule
Collecting
duct
All glucose, all sugar is reasbsorped by
diffusion (more sugar in convulsion
than surrounding blood vessels) and
then actively reabsorb the rest, some
salt is reabsorbed by diffusion, amino
acids are reabsorbed by diffusion and
then actively, due to the
concentration of the blood now, some
water will move by osmosis back into
the blood vessels
Descending tube: only permeable to
water  due to the very salty
environment water moves back into
the blood via osmosis
Ascending tube: only permeable to salt
– more salt is removed back to the
blood actively – hormones
(Aldosterone) can control how much
salt is reabsorbed
Responsible for mineral balance,
expelling extra hydrogen
Most water is reabsorbed and
remaining urine is sent to ureter
Microvilli in tubule increases surface
area for reabsorption  applies to all
tubules
Capillaries surrounding loop of henle
and entire nephron are travelling in the
opposite direction to the tubules for
maximum reabsorption
Compare the process of renal dialysis with the function of the kidney
 Haemodialysis:
o Most common method and uses artificial kidneys
o Blood is sent through is tiny tubules to increase surface
area to volume ratio in order to absorb more of the toxins
and dialysis fluid is bathing these tubes
o The dialysis fluid is perfect plasma – takes away any toxins
and gives blood any missing or compensatory plasma
o Toxins and wastes are removed by diffusion and water
moves by osmosis and ultrafiltration across artificial
membrane
o Pores in membrane allow diffusion of small ions but
prevent large plasma proteins leaving the blood
o An anticoagulant is administered to stop clotting in dialysis
tubing
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 Peritoneal Dialysis
o Portable
o Canular is attached to wrist, ankles or stomach, fluid
pumped in at night and released during the day
Present information to outline the general use of hormone
replacement therapy in people who cannot aldosterone
 Addison’s disease – adrenal cortex produces insufficient levels
of aldosterone
 Shortage of aldosterone can cause kidneys to lose the ability to
maintain a proper balance of sodium and potassium  causing
decrease in blood pressure and volume
 Hormone replacement therapy  supplement hormones are
ingested, either orally or injected
 To correct Addison’s disease, fludrocortisone acetate (Florinef)
Kidney
Blood filtered in nephron
Capillaries travel in
opposite direction to
nephron for maximum
reabsorption
Reabsorbs own nutrients
Maintains homeostasis
Interstitial fluid removes
metabolic wastes and it
can be recycled
Urine is formed
Passive and active
transport in waste removal
Works 24/7
High pressure filtration in
Bowman’s Capsule
Blood doesn’t clot
is administered
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Renal Dialysis
Blood filtered in artificial tubing
Blood tubing travels in opposite direction
to dialysis fluid for maximum
reabsorption
Compensates for lost nutrients by
absorbing nutrients from Dialysis fluid
Homeostasis controlled by a
supplemented diet and Dialysis
Dialysis solutions removes metabolic
waste and cannot be recycled to large
amounts are needed
Used dialysis fluid is the equivalent of
urine
Only passive transport used
Used for about 15 hours per week
No pressure, creating slower process 
compensated for by increased tubing
convulsions
Anti-clotting agent added
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 Must be monitored carefully to avoid fluid retention and high
blood pressure
Compare and explain the differences in urine concentration of
terrestrial mammals, marine fish, and freshwater fish
Type of
Terrestrial
Marine fish
Freshwater fish
organism
organism
Excretory
Urea
Ammonia
Ammonia
product
Excess ions excreted
Ion concentrations are
from salt glands
maintained by
absorption in the gut
and the active uptake
of ion in the gills
Where waste is Kidney
Gills - But some is
Gills – freshwater easily
excreted
converted to urea 
flushes ammonia from
accumulating in the
gills
blood to maintain
osmotic balance
Concentration Varies
Concentrated to
Very dilute to eliminate
depending on
retain as much water
as much water as
water intake,
as possible
possible
activity and
environment
Amount
Varies
Small amounts to
Large amounts to
released
depending on
retain as much water
eliminate as much water
water intake,
as possible
as possible
activity and
environment
Explanation
Water can be
Extremely high salt and Lower salt content in
scarce, and
ion concentration
water than in fish
evaporates
(hypo-osmotic)  fish
(hyper-osmotic)  fish
easily so it must lose a lot of water via
loses ions via diffusion
be conserved
osmosis and gain ions
and gains water via
by diffusion 
osmosis 
Osmoregulation
Osmoregulation
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Explain the relationship between the conservation of water and the
production and excretion of concentrated nitrogenous wastes in a
range of Australian insects and terrestrial animals
Feature
Formation
and energy
required
Toxicity
Ammonia
Formed immediately
after the amino
acid group is
removed from
protein  uses
little energy
Very toxic
Solubility
Highly soluble in
water
Animals
Bony fish, aquatic
invertebrates,
aquatic amphibians
Urea
Produced by liver in
process that requires
more energy than
ammonia
Uric acid
Synthesis
requires more
energy that
urea synthesis
Less toxic than
ammonia
Soluble – can be
moderately
concentrated to
conserve water
Terrestrial amphibians
and mammals
Not very toxic
Not very
soluble in
water
Insects, birds,
and some dogs
Insects
 Covered by a waxy coating impervious to water  little water
 Have Malpighian tubules which collect water and uric acid from
the haemolymph and empty it into the gut
 Useful substances and water are reabsorbed by the intestines
and the wastes leave the body from the anus
Terrestrial animal
 The Bilby and Spinifex hopping-mouse produce very
concentrated urine and tolerate high levels of urea in their
systems  in order to conserve water in arid areas
Discuss processes used by different plants for salt regulation in saline
environments
Halophytes such as the mangrove, found in estuarine environments
have 3 mechanisms by which they remove prevent entry of salt in order
to maintain salt concentrations.
1. Salt exclusion: prevents the entry into their root systems by
filtration
 Passive process and relies on transpiration
 Eg. Grey Mangrove, Red Mangrove, Orange Mangrove
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2. Salt excretion: special glands usually, located on leaves, where
salt is concentrated and then actively secreted from plant
 Active process and relies on rain to wash the salt off
 Eg. Grey Mangrove, River Mangrove
3. Salt accumulation: accumulate salt in part of the plant usually
the bark or older leaves, which are then shed (sacrificial leaves)
 Eg. Milky Mangrove
Perform a first hand investigation to gather information about
structures in plants that assist in the conservation of water
Structure
Function
Conservation of H20
Eg. of
Plant
Waxy/
reflective
leaves
Reflects sunlight
and prevents
osmotic movement
of water
Eucalyptus
Sunken or
fewer
stomates
Traps water that
leaves stomates in
pits, and lessens
stomates
Increase SA: V
ratio
Fewer stomates
Reduces SA of
the leaf exposed
to sunlight
Prevents plants from reaching a
high temperature  resulting
water loss through evaporation
Impermeable to water preventing
water escaping as a result of
evaporation, root pressure etc.
Minimise water-loss due
transpiration
Provides opportunity for
reabsorption
Reduces area for absorption of
solar radiation  reducing
transpiration, therefore heat loss
Minimises the internal
temperature of the plant  Water
loss is preserved as it does not
need to be used for evaporative
cooling
Same benefites of glucose
formation and metabolism
without the water loss
Small
(cylindrical)
leaves
Hanging
leaves
Phyllodes or
caldodes
instead of
leaves
Perform
photosynthesis
but do not lose
water in
transpiration
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Page 37 of 37
Hakea and
Eucalyptus
Desert
plant
Eucalyptus
Acacia and
prickly pear
respectivel
y
Biology - Maintaing a Balance
1.1.1 Identify the role of enzymes in metabolism, describe their chemical composition and
use a simple model to describe their specificity on substrates
Enzymes are catalysts that facilitate chemical reactions
Role of enzymes in metabolism
 Metabolism is a general term used to describe all the chemical reactions that
occur within an organism
 Enzymes are biological catalysts which are in fact able to increase the rate of
chemical reactions but remain unchanged throughout the entire reaction
 Without enzymes, metabolism would occur at a rate to slow to support life
Chemical Composition of Enzymes
 An enzyme is a protein molecule made up of long chains of amino acids,
joined together by peptide bonds forming a polypeptide chain
 The shape of the enzyme is usually determined by its role and the reaction it
controls
 In enzymes the polypeptide chain is folded into a 3D globular shape
 The area of the enzyme that binds to the substrate is known as a an active
site
Specificity on Enzymes
 Enzymes are highly specific in their action: this means that each enzyme
acts on one substrate only
 This is because the shape of the active site matches the shape of the
substrate material
Often enzymes help two substances to combine or for one substrate to split. There are 2
models that show enzyme activity.
The Lock and Key Model
 This model suggests that the substrate fits exactly into the active site of an
enzyme like a key and a lock
 It assumes that the enzyme has a rigid and unchanging shape. This makes
the enzyme highly specific to that substrate
The Induced Fit Model
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 States that the binding of the enzyme to the substrate induces a temporary
shape in the enzyme
 The new shape better accommodates the substrate and the reaction occurs
Enzymes may be aided with the help of co-enzymes (small molecules that help the enzyme
to act) such as molybdenum. Cofactors are the same as enzymes but:
 If organic such as Zn2+, called co-factors
 If organic such as vitamins then called co-enzymes
1.1.2 Identify the pH as a way of describing the acidity of a substance
 pH is a scale which indicates the H + concentration in a substance on a scale
of 0-14
 As a result we are able to identify whether the substance is acidic (pH<7),
basic (pH>7) or neutral (pH=7)
 The higher the concentration of hydrogen ions the lower the pH and vice
versa
1.1.3 Explain why the maintenance of a constant internal environment is important for
optimal metabolic efficiency
 Metabolic efficiency relies heavily upon the optimal operation of enzymes
 However a range of factors inhibit this such as pH, Temperature and
Substrate Concentration
 It is known most enzymes can only work efficiently under a small range of
conditions
 This work of enzymes at optimal capacity is essential to maintain optimum
metabolic efficiency
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 It ensures that external changes do not affect entire metabolic pathways
producing essential compounds. E.g. haemoglobin
 The enzyme catalase found in yeast has an optimum temperature of 35 OC
 If conditions for optimal activity are not met (excess heat) the enzyme is
known to become denatured, where the shape of the active site is
destroyed, preventing activity
1.1.4 Describe homeostasis as the process by which organisms maintain a relatively stable
internal environment
 Homeostasis is the process by which organisms maintain a relatively stable internal
environment in response to changes in the internal and/or external environment
This allows the enzyme's optimal conditions to be met and the body to work
efficiently and kept as stable as possible.
1.1.5 Explain that homeostasis consists of two stages:
 detecting changes from the stable state
 counteracting changes from the stable state
Detecting changes from the stable state

 Any change or information that provokes a response is called a stimulus
 Receptor: an organ or other part which receives a stimulus and transmits it to
organism’s control centre
Mechanoreceptors detect sound, touch, pressure, gravity
 Chemoreceptors detect oxygen, carbon dioxide, water, pH, ions, nitrogenous
wastes, glucose
 Thermoreceptors detect temperature change
 Photoreceptors convert light stimuli into electrical signals

Counteracting changes from the stable state
 After the receptor detects the change, it will respond by counteracting the
change to ensure a stable environment is attained and maintained
 An effector receives the message from the control centre that an
undesirable change must be counteracted, and causes a response to
counteract the change and maintain a stable state (negative feedback)
 They may be muscles that cause movement, or glands that secrete a
chemical substance
1.1.6 Outline the role of the nervous system in detecting and responding to environmental
changes
 The nervous system works to regulate and maintain an animal’s internal
environment in response to a change in the internal and/or external
environment
 The nervous system consists of 2 parts: Central Nervous System (PNS) and
the Peripheral Nervous System (PNS)
 The CNS is composed of the brain, spinal cord and retina. This part acts as
the control centre for all the body’s responses. It receives information,
interprets it and initiates a response
 The PNS is a branching system of nerves that connects receptors and
effectors. These acts as communication channels and pass messages rapidly
to the CNS and back
 The stimulus response pathway occurs as follows
1. Special endings on sensory nerves located in the PNS, such as heat sensors
detect stimuli such as changes in heat, pressure or chemical conditions
2. Receptors relay messages that are processed within the CNS
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3. A response is formulated and the messages are relayed to effector organs or
muscles that bring about the response
1.1.7 Identify the broad range of temperatures over which life is found compared with the
narrow limits for individual species
 Ambient Temperature refers to the temperature of the external environment
 Ambient temperature at particular areas varies daily, monthly and seasonally
and the range of ambient temperatures over the world is very large
 Life is found in this great range of ambient temperatures
 Life can be found in a range of -70 OC to 100OC (e.g. bacteria in snow, boling
springs and undersea vents)
 While this range of ambient temperatures in which life is found is very
broad, then range of ambient temperatures in which individual organisms
can survive is very small
 E.g. Sugar Cane needs a warm frost free environment, thus it only grows in
tropical and sub-tropical regions
 Mammals are generally found in an ambient temperature range of 0 OC to 45
O
C
1.1.8 Compare responses of named Australian ectothermic and endothermic organisms to
changes in the ambient temperature and explain how these responses assist temperature
regulation
Ectotherms
 Ectotherms are organisms that have a limited ability to control their body
temperature as their cellular activates generate little heat by changing its
behaviour through the day.
 Due to this they use the energy from their environment to regulate their
body temperature
 The Central Netted Dragon is known to regulate its temperature by changing
its behaviour through the day
 They sunbake during the morning to absorb heat which activates their daily
body functions. Their level of activity during the day is determined by the
ambient temperature
 Their skin is also darker in the cooler morning and evenings in an attempt to
absorb as much heat as possible. While during they day their skin becomes
much lighter in an attempt to lower the absorption of heat
 During the hottest part of the day, they retreat into their burrows to avoid
the excess heat and the adverse affects it causes to their bodies
Endotherms
 Endotherms use internal metabolic processes which generate heat to
maintain a constant internal temperature independent of the ambient
temperature
 The Red Kangaroo is able to generate heat through its own metabolism, heat
from exercise and from the environment
 When resting the kangaroo loses heat through panting
 It has increased blood flow in vessels supplying the nasal membrane
allowing heat loss through evaporation
 They also have a mass of superficial capillaries on their forelimbs. By
spreading saliva on these, it is able to achieve heat loss through evaporation
 Also they stay in the shade and have decreased activity
1.1.9 Identify some responses of plants to temperature change
 Due to particular temperature extremes in their environment, plants are also
required to develop responses to temperature changes
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 Most desert plants such as the Spinifex have a typically reduced surface area
which is able to reduce water loss and provide a smaller area for solar
absorption
 May have shiny or hairy leaves which reflect solar radiation and reduce heat
absorption
 Curling of Leaves may occur during temperature increases, reducing surface
area exposed to sun light. This minimises heat absorption and water loss
through evaporation at the leaf surface
 Plants such as the Eucalypts will open their stomata in the early morning but
then close them near midday as temperature rises to prevent water loss
through evaporation and transpiration
 Leaves on plants in hot dry area hang vertically to reduce their surface area
exposed to sunlight. In cold shady areas, leaves from plants have a maximum
surface area exposed to the sun
Responses to cold:






Vernalisation: plants such as daffodils require exposure to cold conditions
before they will develop flowers
Plants may leave dormant seeds
Die back of above-ground parts
Plants usually alter growth rate; in tropical regions growth may cease below
15 degrees
Frost-tolerant leaves
In plants, when temperatures are very low, ice forms in spaces outside living
cells. Inside of cell doesn’t freeze because concentration of ions in the cytosol
is greater. Because water concentration is decreasing outside the cells
(because ice is being produced), water moves out of the cells by osmosis,
further increasing cytosol concentration, and lowering freezing point inside
cells even further. Pliable cell membranes prevent cell rupture.
1.2.1 Identify data sources, plan, choose equipment or resources and perform a first-hand
investigation to test the effect of:
 increased temperature
 change in pH
 change in substrate concentrations on the activity of named enzyme(s)
1.2.2 Gather, process and analyse information from secondary sources and use available
evidence to develop a model of a feedback mechanism
 Homeostasis involves the detection of the change in the environment and the
response to that change to maintain a stable internal environment
 The mechanism that brings about this change is called a feedback mechanism. In
feedback systems, the response alters the stimulus
 In Endotherms a constant internal temperature of 36.1 OC to 37.8OC is maintained by
an inbuilt thermostat called the hypothalamus
 Its role is to regulate the internal temperature by detecting and responding to
changes in the stable state caused by stimuli
 Thermoreceptors within the skin inform the hypothalamus of changes in the internal
and external temperature
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The hypothalamus can then respond to an increase in temperatures by sending
messages through the PNS and activating cooling mechanisms such as
vasodilation ( blood vessels dilate, moving closer to the skin surface allowing
heat to escape), sweating and panting
 The hypothalamus can then respond to a decrease in the internal temperature
by directing the PNS to activate heating mechanisms such as increased muscle
activity (shivering), vasoconstriction (constricts blood vessels, reducing heat loss
t0 surrounding areas).
 The involvement of the hypothalamus and PNS in dealing with temperature
regulation is an example of a negative feedback mechanism
 Diagram of FEEDBACK:

1.2.3 Analyse information from secondary sources to describe adaptations and responses
that have occurred in Australian organisms to assist temperature regulation
Behavioural
Physiological
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Endothermic
 Red Kangaroo licks forearms in hot
weather
 Mountain pygmy possum hibernates
in winter
 Spinifex hopping mouse is nocturnal
 Spinifex hopping mouse digs burrows
to escape high temperatures
Ectothermic
 Bogong moths migrate to
Australian Alps in summer to
aestivate (in which they gather in
caves, their metabolism slows and
their body temp drops in order to
assist with temperature
regulation)
 Central netted dragon alters its
posture
 Central netted dragon climbs into
bushes to seek cooler conditions
off the ground, and basks in the
sun when it needs to get warmer
 Magnetic termites pack walls of
their mounds with insulating wood
pulp
 Magnetic termites orient the long
axis of their mounds north-south
 Platypus uses a counter-current
exchange system in its feet to reduce
heat loss
 Mountain pygmy possum hibernates
in winter, body temperature drops
and metabolic rate slows
Bogong moths avoid ice crystals forming in
cells by reducing temperature of body
fluids below their usual freezing point
 Thorny devil is coloured pale when
external temperature is hot to
reflect sun’s rays, and can change
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 Superb Parrot contracts the muscles
controlling its feathers in cold
conditions, causing its cloak to
become ruffled up. This maintains a
layer of trapped air acting as
insulation
Structural
to a darker colour when it is cool
to absorb heat
-
 Bilby has claws on front feet to dig

burrows to escape the heat
Bilby: Large thin ears allow for quick
heat loss
2.1.1 identify the form(s) in which each of the following is carried in mammalian blood:
 carbon dioxide
 oxygen
 water
 salts
 lipids
 nitrogenous waste
 other products of digestion
 Mammalian blood is considered to be a tissue rather than a liquid. It consists
of cells in an extracellular fluid called plasma. 45% of blood is cellular and
55% is plasma
CARBON DIOXIDE:
 It is produced as a waste product of respiration in body cells and occurs in high
concentrations. It is known to diffuse into the bloodstream from body cells and is
carried in 3 ways After entering the bloodstream it may:
1. Be converted into carbonic acid and then changed into hydrogen carbonate
ions. This change from carbon dioxide to carbonate ions happens on the red
blood cells through the enzyme carbonic annhydrase. The ions are
transported dissolved in the plasma (only 70% of the carbon dioxide).
2. 23% of CO2 binds to haemoglobin and forms carbaminohaemoglobin
3. 7% is dissolved directly in the plasma
OXYGEN:
 Essential for body respiration and is inhaled through the lungs, bringing it across the
respiratory surfaces of the lung.
 It binds with haemoglobin in red blood cells, forming oxyhaemoglobin.
WATER:
 Water is the solvent of plasma and travels in plasma as water molecules
 Makes up 60% of the volume of blood
SALTS:
 In blood, salts transported directly in plasma as dissolved positive and
negative ions. E.g. Cl- and Mg2+
LIPIDS:
 Many lipids are water insoluble and only travel in the blood when they are
coated in proteins becoming lipoproteins and travel as HDL or LDL
 Digested lipids are changed into triglycerides in the lining of the small
intestine
 These can then be transported as chylomicrons which are clusters of
triglycerides, phospholipids and cholesterol, wrapped in a coat of protein.
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 These are released into the lymph and eventually pass into the veins where
they are transported in the plasma to the tissue cells
NITROGENOUS WASTES:
 Nitrogenous waste is produced by the deamination of proteins and nucleic
acids (removal of nitrogens as part of amine group)
 The waste is ammonia, but as this is toxic most mammals convert the
ammonia to urea which can be transported in blood plasma
 Conversion occurs in the liver and the kidney’s filter the urea from the blood
OTHER PRODUCTS OF DIGESTION:
 They are mainly water soluble and transported in the plasma
 Includes amino acids, sugars, glycerol and vitamins
2.1.2 Explain the adaptive advantage of haemoglobin
 Haemoglobin is a globular protein made of 4 polypeptide chains which
enclose a haem group
 Each haemoglobin consists of a protein molecule called globin and 4
pigmented molecules made of a compound called haeme each of which has
an atom of iron at its centre
 The iron gives blood its red colour
 Each of these haemoglobin molecules is able to bind with 4 oxygen
molecules or 8 atoms
 When one oxygen molecule combines with 1 of the haeme group, there is a
slight change in the shape of the molecule which increases the affinity of
haemoglobin for more oxygen
The adaptive advantage
 If blood carried oxygen without haemoglobin, the oxygen would have to be
dissolved directly into the plasma
 However oxygen is not very soluble in water
 If oxygen was carried only by being dissolved in blood plasma, 100mL of
water would only dissolve 0.2mL of O2
 The presence of haemoglobin increases the oxygen carrying capacity of
blood by 100 times allowing 20mL of O2 per 100mL of blood.
 Oxygen can combine with haemoglobin to form oxyhaemoglobin increasing
the oxygen carrying capacity of blood
 Mammals are endotherms and use the heat from internal metabolic
processes to maintain body temperatures
 It is therefore an
adaptive advantage for mammals to have
haemoglobin in
their red blood cells to
carry more O2 to release
energy to maintain
body temp.
2.1.3
Compare the
structure of
arteries, capillaries and veins in relation
to their function
2.1.4
Arteries
 Carry blood away from heart (at high blood pressure)and this placed on
arteries from the heart pumping creates great stress.
 This is why the arteries are thick walled, elastic and muscular.
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 Arteries have muscle fibres in them which can contract and relax with each
heartbeat allowing for the maintenance of constant blood pressure and rate
of blood flow to all tissues
 The contracting and relaxing of the arterial walls is also what causes the
pulse on your wrist or neck).
 Arteries have a smaller lumen than veins
Veins:
Capillaries:
 Veins carry blood back to the heart at comparatively lower pressures and as
a result have thinner walls than arteries, less muscles and a wider diameter
(lumen)
 Since there are no thick muscular walls to keep the blood pulsing along, the
veins have a series of valves which prevent the blood from back-flowing on
its way back up to the heart.
 The blood in veins is kept moving through the contraction of muscles
surrounding your veins such as leg muscles
 Capillaries are an extension of the inner layers of the arteries and veins and
they are the basic structures that connect arteries and veins
 Capillaries are only one cell thick, and are so narrow, that only one red blood
cell can pass at a time.
 Capillaries surround all tissue cells
 Thus, they provide a very large surface area over which exchange of
materials between blood and body cells can occur.
 Diameter of 7-10 micrometers
2.1.4 Describe the main changes in the chemical composition of the blood as it moves
around the body and identify tissues in which these changes occur
Pulmonary circuit:
 It is mainly composed of the lungs and the heart.
 Blood enters the right atrium of the heart via the vena cava:
– The blood is deoxygenated, and high in carbon dioxide
– It is low in glucose and other nutrients; it is also high in urea, other
nitrogenous wastes and various poisons.
As the heart beats, the right ventricle pumps the blood through the pulmonary
artery, to the lungs:
– Here the blood gains oxygen, and loses its carbon dioxide.
– The blood then enters the left atrium via the pulmonary vein.
Systemic circuit
 The left ventricle pumps oxygenated blood throughout the body through the
aorta.
 As the blood moves throughout the body, various changes occur
– The blood loses oxygen and gains carbon dioxide in all body cells, as
respiration occurs. Glucose levels also drop.
Liver:
 Levels of glucose are regulated – excess glucose is changed to glycogen, or
glycogen stores are changed to glucose
 Excess amino acids are changed to ammonia, and then to urea
 Poisons are also reduced, as the liver changes them to less toxic forms
Intestines:
 Levels of nutrients from digestion increase.
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 Glucose, amino acids, ions, lipids and other substances from food enter the
blood. The increase is through the small intestines reabsorption of food
Kidneys:
 Salt and water levels are regulated
 All urea is removed, toxins are excreted into the urine
 The changed blood, again highly deoxygenated, then flows back to the
pulmonary circuit.
Bone Marrow
 New red blood cells are picked up as well as white blood cells
Brain
 Picks up hormones needed to regulate body functions from a number of
glands including the pituitary gland
Reproductive Organs
 Picks up hormones for control over reproductive cycle
Pancreas
 Picks up hormones such as insulin which assists in maintaining blood glucose
levels
2.1.5 Outline the need for oxygen in living cells and explain why removal of carbon dioxide
from cells is essential
 All living cells are known to require oxygen for respiration
C6H12O6 + 6O2
6H2O + 6CO2 38ATP
 Cells require energy to survive, energy which comes from respiration which
requires energy
 Respiration produces water, carbon dioxide and energy needed for metabolic
processes
 A by product is CO2 which when dissolved in water produces H2CO3 which is
able to disassociate into its ions and increase the hydrogen ion
concentration, lowering the pH
 The activity of enzymes is optimum in a very limited pH range
 Under such a decreased pH, the metabolic pathways of the organism are
affected and thus removal of CO2 from the organism is essential
2.1.6 Describe current theories about processes responsible for the movement of materials
through plants in xylem and phloem tissue
Xylem
 The xylem transports water and dissolved mineral ions in one direction from
the roots to the leaves
 The water enters the roots through osmosis but energy may be required for
the uptake of ions if it is against the concentration gradient
 Transport of water depends on transpiration and the physical properties of
water
 Water moves from the roots to the leaves where it is lost through
transpiration at the stomata
 Evapouration of water from the leaf cells through the stomates initiates the
pull of the transpiration stream
 Water is then drawn up the xylem tubes to replace this loss
 The movement of water through narrow tubes is known as capillarity and is
caused by adhesion and cohesion
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 Cohesion is where molecules tend to bind together causing the water to
form a continuous stream up the plant, pulling it up, replacing any
immediate water loss
 Adhesion, water sticks to the sides of the xylem tubes, pulling the water up
Phloem
The theory
 Movement of organic molecules. E.g. sugars, amino acids and hormones in
the phloem is called translocation
 Enables a plant to distribute resources where they are needed, but
especially to growing plants and reproductive structures such as fruits and
seeds
 This forms of transport carries sugars from an areas of High hydrostatic
pressure (source) to an area of low hydrostatic pressure (sink); known as
source-path-sink system or pressure flow theory.
 It is driven by a pressure gradient generated osmotically
 In plants it is known there are sources of nutrients. E.g. leaf cells are a source
of glucose and amino acids
 Both of these products as well as other nutrients are transported into the
phloem by active transport in 1 of 2 ways: Symplastic Loading and Apoplastic
Loading
 As sugars enter the phloem the concentration of phloem sap increases
 This causes the entry of water by osmosis from the surrounding cells as
water concentration lowers. This resulting high hydrostatic pressure causes
water and dissolved solutes to flow to an area of low hydrostatic pressure
(the sink)
 A sink is a region of the plant where sugars and other nutrients are actively
being removed from the phloem
 As sugars move out of the phloem the water does too as their is a higher
concentration of water in the phloem.
 This reduces the pressure in sieve cells to normal
2.2.1 Perform a first-hand investigation to demonstrate the effect of dissolved carbon
dioxide on the pH of water
2.2.2 Perform a first-hand investigation using the light microscope and prepared slides to
gather information to estimate the size of red and white blood cells and draw scaled
diagrams of each
2.2.3 Analyse information from secondary sources to identify current technologies that
allow measurement of oxygen saturation and carbon dioxide concentrations in blood and
describe and explain the conditions under which these technologies are used
Technology
Pulse Oximeter
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How it works
 Measures
monitors the
oxygen
saturation of a
patient's blood
 A peg like device
that sits on the
finger and
measures the
transmission of
light through
tissues
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The conditions it is used
 Technique is non
invasive and is
painless allowing
it to be used in
various
conditions
 Also used during
surgeries to
monitor patients
under anaesthesia
 Also used for
patients
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 Works by
emitting a red
and infrared light
at different
wavelengths
 Absorption at
these
wavelengths
differs
significantly
between
oxyhaemoglobin
and its
deoxygenated
form; therefore
oxygen
saturation can be
determined from
the amount of
light absorbed
 Measures the
amount of CO2
and O2 in the
blood.
 Analysis
evaluates how
effectively the
lungs are
delivering
oxygen and
removing CO2
 A blood sample
usually taken
from the radial
artery is tested by
electrochemical
methods in a
blood gas
analyser
 It measures the
saturation of
oxygen by
measuring how
much O2 is
attached to
haemoglobin and
comparing it to
the maximum.
 Determines CO2
concentration by
measuring
bicarbonate
content and
blood pH levels
 Invasive
technique that
takes time
between
sampling and
delay
 An instrument
incorporating an
Arterial Blood Gas Analysis
(ABG)
Capnometer
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undergoing
medical
ventilation
 Used when there
are signs of
dangerously low
oxygen or carbon
dioxide levels
 Helps for
diagnosing as
well as
monitoring
patients
 Helps to monitor
patients under
anaesthesia
 Non – invasive
and portable
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infrared dot
detector
assembly, used to
analyse CO2
gases and in
medical
applications to
monitor air
exchange in the
lungs of patients
on ventilators or
anaesthesia
 It can evaluate
the respiratory
conditions of
spontaneously
breathing
patients
capnometers can
be used for inhome care and in
general wards
Generally the conditions under which
these are used
 To assess
respiratory diseases
and other conditions
that may affect the
lungs, such as
emphysema,
pneumonia and
silicosis
 To manage patients
receiving oxygen
therapy, mechanical
ventilation or
anaesthesia
2.2.4 Analyse information from secondary sources to identify the products extracted from
donated blood and discuss the uses of these products
When blood is donated it can be used immediately as whole blood to treat patients who
have lost 20% or more blood or if their blood’s oxygen carrying capacity is reduced.
Alternatively it can be separated into its individual products
 Red blood cells: Used to increase the amount of oxygen that can be carried
to the body’s tissues; given to anaemic patients, or people whose bone
marrow do not make enough red blood cells. Can be given to those who
require blood after extensive losses
 Platelets: They are essential for the coagulation of the blood. Given to
people with cancer of the blood (leukaemia or lymphoma). Patients
undergoing chemotherapy, whose blood does not make enough platelets,
are given this.
 Plasma: (Usually in the form of fresh frozen plasma ). This liquid portion of
the blood, is given to people with clotting disorders (such as haemophilia),
and also used to adjust the osmotic pressure of the blood (to pull fluids out
of tissues). Some products are derived from plasma
 White blood cells: Infection fighting component of the blood. Very rarely
given, but are used when cell count is very low or when the bodies white
blood cells are not working properly
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 Immunoglobulins: Also called gamma globulins, immune serum, or
antibodies, these are also infection fighting parts of the blood plasma. Given
to people who have difficulty fighting infections, eg AIDS sufferers.
2.2.5 Analyse and present information from secondary sources to report on progress in the
production of artificial blood and use available evidence to propose reasons why such
research is needed
There are various reasons as to why research into artificial blood is essential:
1. Antigen-antibody reactions to antigens on donated red blood cells are
dangerous complications, so donor blood must be cross-matched and typed
 Can be avoided using artificial blood, when no red blood cells are given
2. Artificial blood can be stored for more than one year, compared with about
one month for donor blood using standard methods
3. Donor blood can transmit viruses such as HIV. Some pathogens may escape
screening.
 Many countries are prohibiting blood donations who have a risk of carrying
the causative agent for bovine spongiform encephalopathy (BSE)
 With artificial blood, pasteurisation may be used to remove all pathogens
4. Shortage of donor blood to help victims of emergencies, civil conflicts, and
natural disasters. Artificial blood could be manufactured on a large scale,
dropping prices and making it more readily available in poorer countries.
The substitutes being developed have a number of advantages over real blood
1. They can be stored for up to 2-3 years
2. They are free of any infectious agents
3. They are readily available in large supply, solving the donor problem
4. All blood groups accept the alternatives removing the need for cross matching
The main alternatives being developed are the following
Perflurochemicals (perflurocarbons):
Synthetic and inert, are completely sterile
Cheap to produce, compared to using real blood.
Can dissolve 5 times more oxygen than blood.
Free of biological materials, therefore no risk of infections
BUT - must be combined with other materials to mix in with the bloodstream
(eg lecithin). This changes how well artificial blood can flow through blood
vessels thus more research is needed
 Haemoglobin Based Oxygen Carriers (HBOCs):
o Made from haemoglobin extracted from red blood cells
o Haemoglobin is not contained in membrane - cross matching unnecessary
o Can be stored for a long time
o BUT - haemoglobin tends to oxidise to a different form, break down, and can
no longer carry oxygen. This haemoglobin however must be subject to
clinical trials as they are unprotected by cell membranes and thus
unprotected from degradation
Dextrose Solution:
o Made of 4% glucose solution in a fluid with equal salinity to blood
o Only used to restore blood pressure after accidents.






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2.2.6 Choose equipment or resources to perform a first-hand investigation to gather firsthand data to draw transverse and longitudinal sections of phloem and xylem tissue
3.1.1 Explain why the concentration of water in cells should be maintained within a narrow
range for optimal function
There are 4 main reasons
1. Living cells are known to work best in an isotonic environment, in which the
concentration of solutes in the internal and external environment of the cell is the
same. If the concentration of solutes in the internal or external environment
changes, cells may take in or lose water through osmosis. This may lead to death
through plasmolysis or cytolysis
2. Water also
has a high heat capacity
allowing it to
absorb or lose
large
amounts of heats
without
a
significant change
in
temperature.
Maintenance of a constant body temperature is essential for many organisms and
this can only be achieved through the maintenance of adequate amounts of water.
3. Enzymes require a range of specific conditions for their optimum functioning, some
of which is related to the concentration of water and solutes in the internal and
external environment. Thus a change in concentration of water in cells could
interfere with teh functioning of enzymes
4. All chemical reactions in the body occur in an aqueous medium, thus the main role
of water is to provide a medium for bodily reactions
3.1.2 Explain why the removal of wastes is essential for continued metabolic activity
 Metabolism produces a number of waste products in living organisms such
as CO2, excess salts and nitrogenous wastes
 An accumulation of wastes can be toxic to the body or can disrupt metabolic
activity
 E.g. An excess of carbon dioxide can increase pH, which affects enzyme
activity
 This is why they need to be removed, or converted into a less toxic form such
as when amino acids are broken down (deamination), a nitrogenous waste
called ammonia is produced which must be removed or changed into a less
toxic form
3.1.3 Identify the role of the kidney in the excretory system of fish and mammals
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 Primary roles of kidneys are regulation of salt/water concentrations in the
body (osmoregulation), and removal of nitrogenous wastes
 Kidneys also filter the blood, excrete hormones and vitamins, maintain a
correct balance of salts by excreting those in excess, help to maintain pH of
the blood, and reabsorb nutrients that are needed
 In fish, kidneys maintain constant concentration of internal fluid for the
cells
 In mammals, excretion of urea, and regulation of internal salt/water
concentrations, occurs in the kidney
3.1.4 Explain why the processes of diffusion and osmosis are inadequate in removing
dissolved nitrogenous wastes in some organisms
 Diffusion and osmosis are both examples of passive transport, relying on
random movements of molecules.
 Diffusion is too slow for the normal functioning of the body and is not able
to selectively reabsorb useful solutes.
 Osmosis only deals with the movement of water and thus would only allow
water to move out of the body, not the nitrogenous wastes.
 In the kidney, some useful products are reabsorbed into the body – this
would not be possible with diffusion (active transport needed)
 Osmosis without active reabsorption of water would result in excess water
loss
 The kidney functions by using excreting all the blood substances in the
nephron ‘outside’ the body and then selectively (actively) reabsorbing useful
materials
3.1.5 Distinguish between active and passive transport and relate these to processes
occurring in the mammalian kidney
 Passive transport does not require expenditure of energy (e.g. diffusion,
osmosis), as materials move down a concentration gradient
 Facilitated diffusion: specific carrier protein molecule assists diffusion
 Occurs in filtration, and in osmosis of water back into the blood



Proximal tubule: K+ and HCO3- ions out, ammonia (NH3) in
Thin section of ascending limb of loop of Henle: NaCl out
Osmosis of water out in tubules, descending limb of loop of
Henle, and collecting duct
Active transport requires expenditure on the part of the organism, and often goes
against concentration gradient
 Specific carrier proteins in membrane may bind with substance
and carry it across the membrane
 Endocytosis: a pouch forms that carries matter through the
membrane

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Enables cells to maintain stable internal conditions in spite of extreme variation in
the external environment
Occurs in secretion of substances into the nephrons, reabsorption of nutrients back
into the blood, and selective reabsorption of salts required by the body




Proximal tubule: glucose/amino acids out, H+ in
Distal tubule: HCO3- out, K+ and H+ in
Na+ out in tubules, thick segment of ascending limb of loop of
Henle, and collecting duct
Poisons and drugs secreted in proximal and distal tubules
3.1.6 Explain how the processes of filtration and reabsorption in the mammalian nephron
regulate body fluid composition
 Each kidney is made up of about one million small filtering units called
nephrons, which produce urine
 It is a regulatory unit which absorbs and secretes substances to maintain fluid
concentration and as a result maintain homeostasis
 A nephron is a long twisted tubule made of a number of sections: a
Bowman’s capsule, connected to a proximal tubule, leading to the loop of
Henle, which connects to the distal tubule. This all joins to the collecting duct
which leads to the bladder.
 Nephrons are surrounded by dense network of capillaries (providing a large
surface area for reabsorption)
 Starting point is Bowman’s capsule, situated in the cortex
 Leads to a narrow, convoluted tube, which makes a loop in the medulla back
to the cortex, then joins a collecting duct
 Collecting duct transports urine to pelvis of kidney, which leads to the ureters
 3 processes in formation of urine: filtration, reabsorption, secretion
Filtration
 Blood brought to kidneys by renal artery, which divides into smaller vessels
 Vessels form a network of capillaries called a glomerulus, when they reach
Bowman’s capsule
 The structure of the glomerulus means that it acts as an ultrafilter
 Very high blood pressure in glomerulus, as well as very permeable capillary
walls, non-selectively force some parts of blood through Bowman’s capsule
into the kidney tubule to become ‘glomerular filtrate’
 Glomerular filtrate consists of blood plasma, and small soluble molecules
which pass through by passive filtration; no blood cells, platelets or large
plasma proteins
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Water, nitrogenous wastes (urea), food materials (glucose,
amino acids, vitamins), other ions (e.g. bicarbonate), other
ingested substances (penicillin), and hormones
Filtrate forced into proximal part of tubules nephron’s tubules

 Along length of tubule, composition of filtrate adjusted until it contains only
unwanted substances (urine)
Reabsorption
 As filtrate travels down the tubule, materials
the body can re-use are selectively reabsorbed into
the large capillary network surrounding the
tubules
 Glucose, amino acids, vitamins,
bicarbonate, and water reabsorbed through
microvilli on tubule walls
 Reabsorption of ions occurs at different rates depending on feedback from
body
 Occurs in proximal/distal parts of tubule, and in loop of Henle
 Glucose, amino acids reabsorbed in proximal tubule
 Sodium/potassium ions reabsorbed in proximal/distal tubules; chlorine ions
and water follow passively into the blood
 Bicarbonate ions reabsorbed in proximal/distal tubules to maintain blood pH
Secretion
 Selective process by which body actively transports substances from blood
into nephrons
 Hydrogen ions secreted in proximal/distal tubules to regulate blood pH
 Drugs (e.g. penicillin) and poisons identified by liver are actively secreted into
proximal tubule
Regulation of Body Fluid Composition: Recap
 Proximal tubule
 Nutrients such as glucose and amino acids reabsorbed
 Salts reabsorbed, and water follows by osmosis
 Hydrogen ions and drugs/poisons secreted
 Loop of Henle
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 Descending part: walls permeable to water but not to salt
 Water passes by out by osmosis, until filtrate is isotonic with external
medulla
 Ascending part: walls permeable to salt but not to water
 Salt (NaCl) passes out passively across thin-walled section as external solute
concentration decreases, and then actively across thick-walled section
 *Salt passing out makes interstitial fluid of medulla quite concentrated
 Distal tubule
 Salts reabsorbed, and water follows by osmosis
 Bicarbonate reabsorbed, hydrogen ions secreted
 Collecting Duct
 Walls permeable to water but not salt, so water passes out by osmosis
3.1.7 Outline the role of the hormones, aldosterone and ADH (anti-diuretic hormone) in
the regulation of water and salt levels in blood
2 hormones maintain salt and water levels in the blood: Anti-diuretic hormone (ADH) and
Aldosterone.
Anti-Diuretic Hormone
1. ADH is made by the hypothalamus but it is stored in the pituitary gland.
2. It is able to regulate the reabsorption of water by varying the permeability of the
collecting tubule and the distil tubules.
3. Receptors in the hypothalamus monitor the concentration of the blood:
4. If the salt concentrations in the blood are too HIGH then the receptors in the
hypothalamus detect this and secrete higher levels of ADH through the pituitary gland.
5. This increases the permeability of the collecting tubule allowing more water to be
reabsorbed back into the blood and as a result, lowering salt concentrations and
concentration of urine.
6. When salt concentrations are LOW in the blood less ADH is secreted decreasing the
permeability of the collecting tubule, allowing less water to be absorbed into the blood
stream. Concentration of urine.
Aldosterone
 Aldosterone is produced by the adrenal glands and regulates the level of salt
in the blood by varying its absorption in the nephron.
 Aldosterone increases permeability of walls of distal tubules to Na + ions; Clions follow by diffusion
 Pressure-sensitive receptors in the kidney detect fall in blood pressure (LOW
SALT LEVELS) , levels of aldosterone increase.
 This results in more salts being reabsorbed into the blood stream from the
nephron.
 However water also moves out of the nephron due to the process of
osmosis.
 The result is that Na+ levels, blood volume and pressure increase helping to maintain
constant filtration of the blood at the glomerulus
 When HIGH SALT LEVELS are detected, levels of aldosterone decrease and
subsequently the amount of salt and water reabsorbed decreases as well.
 IMPORTANT: ADH is relevant to salt levels, controlled via water retention. But ADH
only affects the concentration of salts and never their actual levels
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3.1.8 Define enantiostasis as the maintenance of metabolic and physiological functions in
response to variations in the environment and discuss its importance to estuarine
organisms in maintaining appropriate salt concentrations
Enantiostasis is the maintenance of metabolic and physiological functions in response to
variations in the environment
• An area where the freshwater from the river meets the saltwater of the sea is called
an estuary
• From low tide to high tide, water can flow in either the salty ocean (high salt water
levels) or from freshwater rivers (low salt water concentration) – this causes great
variation in the levels of salt in the water
• As a result estuarine organisms such as fish, invertebrates, mangroves carry out
enantiostasis to maintain suitable internal salt concentration
• Estuarine fish who maintain an internal solute concentration similar to the external
concentration are known as osmoconformers and do this by moving small nonessential organic molecules like amino acids in and out of their tissues, depending
on their external environment (salt concentration). E.g. Fiddler Crab
• They do this to ensure the osmotic pressure is the same in the internal and external
environment, minimising any water movement associated with changing salt
concentrations
• Stenohaline organisms that remain in the open sea can tolerate little or no change in
the salinity of their environment
• Euryhaline can tolerate a wide range of salinities:
 Such organisms are osmoconformers (must be able to function with
fluctuating internal salt concentrations) or osmoregulators (must have
physiological mechanisms to control salt concentration of their bodies)
 Most marine invertebrates are osmoconformers. In contrast, marine
mammals and most fish are osmoregulators, maintaining homeostasis
regardless of the osmotic pressure of the environment
3.1.9 Describe adaptations of a range of terrestrial Australian plants that assist in
minimising water loss
Xerophytes is the general term for plants adapted to living arid or dry conditions.
Many Australian terrestrial plants show a number of adaptations to conserve and
minimise water loss
• Many xerophytes have:
 Deep tap root systems to reach underground water, and wide, shallow roots
to soak up surface moisture
 Thick cuticle – stops uncontrolled evapouration through leaf cells
 Small surface area – less surface area for evapouration
 Low stomata density – smaller surface area for diffusion
 Sunken stomata, stomatal hairs, rolled leaves – maintaining gumid air
around stomata
Examples
• The Mulga has branches arranged so that any rain falling is directly channelled into
the roots
• Eucalyptus trees are hard with waxy cuticles reducing the amount of water loss
through transpiration. They also have leaves which hang vertically for minimal sun
exposure
• Acacia Pycnantha has phyllodes (a leaf stalk that has been modified to carry out the
major role of photosynthesis without having the density of stomatas
•
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•
•
Spinifex Grass has extensive root systems that can reach underground water. Their
leaves are long and thin to reduce water loss and roll up to hide stomates whereby
preventing water loss
Porcupine Grass – high humidity is maintained around stomates openings, reducing
the effect of wind on water loss
3.2.1 Perform a first-hand investigation of the structure of a mammalian kidney by
dissection, use of a model or visual resource and identify the regions involved in the
excretion of waste products
•
•
•
•
Renal capsule: thin layer of cells that surrounds each kidney
Ureter: transports urine away from the kidney
Glomeruli give cortex its granulated appearance
Loops of Henle give the medulla its striated appearance
3.2.2
Gather, process and analyse information from secondary sources to compare the process
of renal dialysis with the function of the kidney
Renal dialysis is an artificial process in which wastes in blood are removed by diffusion across
a semi permeable membrane
Used for people who have impaired kidney function, where products of metabolism
(including urea) build up in the body. High concentrations of these cause tiredness etc. The
level of creatinine in the blood is often a measure of the degree of kidney failure.
There are 2 main types of renal dialysis:
Haemodialysis
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Blood is drawn from an artery, and passes through dialysis tubing made of
semipermeable material
• Tubing passes through a container of dialysing fluid (balanced salt solution)
• Membrane allows wastes to diffuse across into dialysis solution, but not
blood cells, platelets or proteins
 Excess water is also removed by osmosis
 This step is similar to filtration stage of normal kidney function
•
Any salt or drug that is in a higher concentration in the dialysing fluid than in the blood, will
diffuse into the blood
 This step is similar to the passive transport components of reabsorption
• Dialysing fluid is constantly replaced to maintain concentration gradients and
ensure maximum waste removal
• Anti-clotting agent heparin is added to the cleaned blood, and the blood is
returned to the body
• Haemodialysis can be used only 4-5 hours at a time, 3 times a week
 Because heparin is dangerous, risk of infection, and blood cells
may be damaged as they pass through plastic tubes
Peritoneal dialysis
• Unlike haemodialysis, peritoneal dialysis undertaken inside the body
• Dialysis solution introduced into peritoneal (abdominal) cavity through a
catheter
• Natural membrane lining peritoneal cavity is a partially permeable
membrane, so waste products and excess water from body can pass through
membrane into dialysis solution
Continuous ambulatory peritoneal dialysis (CAPD)
• Sterile dialysis fluid is introduced into abdomen through a catheter, and fluid
‘dwells’ in the cavity until the next change
• At the end of the dialysing period, used fluid is allowed to run out into an
empty drainage bag
Automated peritoneal dialysis (APD)
• Person connects via a catheter to a cycler machine to perform overnight
dialysis
Comparison
Kidney
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1. Type of membrane
2. Where filtration occurs
3. Products Removed
4. Products not removed
(similarity)
5. Type of transport
6.Where diffused blood is
returned
7. Anti clotting agent
8. Frequency
Permeable membrane which varies
with hormone
Glomerulus
Fluid component of blood. E.g.
urea, amino acids, salts and water
Red and white blood cells,
proteins, platelets, large molecules
Active and passive transport occurs
throughout the nephron
Via the tubule
No
Continuous
Partly permeable plastic membrane
Blood taken from the patients
artery is passed through the partly
permeable plastic tubing in the
dialysis machine
Waste products
Red and white blood cells, proteins,
platelets, large molecules
Passive
Via the dialysis tub to a vein in the
arm
Yes, Heparin
3-5 hrs 5 times a week
3.2.3 Present information to outline the general use of hormone replacement therapy in
people who cannot secrete aldosterone
•
•
•
•
•
•
•
•
•
•
•
•
•
Causes of low aldosterone levels
Diseases of adrenal glands or pituitary glands, surgery on adrenals,
medications that prevent thrombosis
Hypoaldosteronism is a condition where people fail to secrete aldosterone.
Addison's disease is a disease with these symptoms
Inability to secrete aldosterone from adrenal cortex, caused by
shrinking/destruction of adrenal gland
Effect of low aldosterone levels due to Addison’s disease
Excessive amounts of sodium are excreted with high urine output
Results in dehydration, low sodium levels, high potassium levels, high acid
levels, and lowered blood pressure/volume, which can lead to heart failure
Symptoms: fatigue, muscle weakness, weight loss, skin changes
Treated with hormone replacement therapy using a synthetic hormone
called fludrocortisone (Florinef)
It is taken as a once a day pill and is highly successful in treating those with
Addison’s disease
Careful monitoring needed to avoid fluid retention and high blood pressure
Patients advised to increase salt intake
3.2.4 Analyse information from secondary sources to compare and explain the differences
in urine concentration of terrestrial mammals, marine fish and freshwater fish
•
•
Significant amounts of water are reabsorbed through the loop of Henle,
resulting in hypertonic urine production
Animals without loops of Henle in their
kidney tubules produce a
hypotonic urine
______________________
Freshwater Fish
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Excrete large amounts of dilute (hypotonic) urine, to lose water
• Problem: Water tends to diffuse into body and ions tend to diffuse out, so
fish needs to remove water, and keep salts
 Kidneys produce copious amounts of dilute urine to remove water
 Kidneys actively reabsorb salts (NaCl) to prevent salt loss
 Freshwater fish rarely drink water
• Maintain higher concentration of solutes in their body (hypertonic to their
surroundings)
• Ammonia is excreted in large volumes of dilute urine, and across the gills
Saltwater Fish
Excrete small amounts of isotonic urine, to remove salt while limiting water loss
• Problem: Water tends to diffuse out of their body and ions tend to diffuse
into body, so fish needs to retain water
 Excrete small amount of isotonic urine to retain water and excrete salt
 Kidneys and gills actively excrete salts (MgSO4)
 Constantly drink saltwater to replace water losses
• Internal body fluids are less concentrated than surroundings (hypotonic to
their surroundings)
• Ammonia is excreted via
the gills
*Marine cartilaginous fish (sharks and
rays) have tissues isotonic to
seawater, so avoid osmoregulation
problems
Terrestrial Mammals
Excrete small amounts of concentrated (hypertonic) urine. Those in dry or desert
environments excrete very small amounts of highly concentrated urine to retain as
much water as possible
• Problem: conserving water while excreting nitrogenous wastes
• Deamination: Excess amino acids are broken down to urea in the liver
 Removing amino group (-NH2) to form urea, and converting the rest to a
carbohydrate
 Kidneys remove urea from the blood, and excrete urea with the urine
• Urine leaves kidneys via ureters, and is stored in the bladder until urination
Reptiles (the goanna)
Excrete semi-solid uric acid
• When goanna is dehydrated, number of active tubules in kidney is reduced,
reducing amount of filtrate produced and conserving water
• As water taken in increases, the number of tubules activated also increases
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3.2.5 Use available evidence to explain the relationship between the conservation of water
and the production and excretion of concentrated nitrogenous wastes in a range of
Australian insects and terrestrial mammals
Animals excrete nitrogenous wastes in different forms because they have different
amounts of water available to them.
 Ammonia
 Highly soluble in water and highly toxic
 It must be diluted in large quantities of water and quickly excreted along with
the water
 Least amount of energy required as it does not have to be converted to a less
toxic form first.
 Hence, it is the waste product of most aquatic animals
Urea
 Moderately soluble and moderately toxic
 Can be safely stored in the body for longer in a more concentration solution.
Therefore urea requires less water to remove than ammonia
 Hence, it is the waste product of mammals, some other
terrestrial animals, adult amphibians, sharks, and some bony
fish
Nevertheless, excreting urea is the major source of water loss in mammals
Uric acid
 Least soluble (highly insoluble) and low toxicity
 Can be safely stored in the body for extended periods of time, so little water
is expended to remove it
 Hence, it is the waste product of birds, many reptiles, and
insects, which need to conserve water
Organism
Spinifex hopping
mouse
Red kangaroo
Waste product(s)
Urea, in a
concentrated form
Urea, in
concentrated urine
Insects
(e.g. ‘Lord Howe
Island Stick
Insect’)
uric acid
•
•
Explanation
Lives in a very arid environment. Drinks very little water and
excretes urea in a concentrated form, so that water can be conserved.
Has a very efficient excretory system that recycles nitrogen and urea
to make a very concentrated urine. This allows them to survive in
very arid environments
Covered with a cuticle impervious to water.
Conserve water by producing a dry paste of uric acid.
Australian terrestrial mammals that live in predominantly arid areas, such as
the Bilby, must produce very concentrated urine and tolerate high levels of
urea in their systems.
Some insects excrete ammonia as a vapour across the body surface rather
than as a solution of urine, an adaptation for conserving water.
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•
Insects have Malipighian Tubules which collect water and uric acid from the
haemolymph and empty it into the gut. Useful substances and water are
reabsorbed by the intestines and wastes leave the body from the anus
3.2.6 Process and analyse information from secondary sources and use available evidence
to discuss processes used by different plants for salt regulation in saline environments
•
•
Halophytes are plants adapted to living in salty conditions
3 main mechanisms are used by such plants to control salt levels:
 Salt Exclusion
 Salt Excretion
 Salt Accumulation
Salt Excluders
• They are plants that prevent the entry of salt into their root systems by filtration
• It is a passive process and relies on the transpiration stream
• The Grey Mangrove (Avicennia Marina) can exclude 95% of salt via the filtration
systems in the roots and lower stems
• Other plants employ this mechanism are the Red Mangrove and Orange Mangrove
Salt Excretor
• Have special salt glands, usually in the leaves
• Salt is concentrated here and then actively secreted from the plant
• The salt can often be seen as salt crystals on the leaves and from here the rain can
wash them off.
• E.g. Grey and River Mangrove
Salt Accumulator
• Concentrate or accumulate salt in a part of the plant, usually the bark or older leaves
which are then shed
• The Milky Mangrove sheds old leaves full of salt
3.2.7 Perform a first-hand investigation to gather information about structures in plants
that assist in the conservation of water
Method 1:
• Looked at Acacia pycnantha plant
• Phyllodes instead of leaves to reduce water loss through transpiration
• Looked at an eucalyptus leaf
• Thick waxy cuticle
 Water drop on the leaf surface stays together
 Reflective leaf surface
 Woody petiole
 Leaf orientation on the tree
Method 2:
1) 4 measuring cylinders were filled with water to the top graduation, and some
paraffin oil added to each, to form a visible surface layer
2) One plant was placed into the first measuring cylinder, with leaves protruding
from the top.
3) Similarly, the lower epidermis of the 2nd plant was smeared with petroleum
jelly, and then placed in the 2nd measuring cylinder. The upper epidermis of
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the 3rd plant was smeared with petroleum jelly, and both sides of the 4th plant
were smeared with petroleum jelly.
4) The measuring cylinders with plants were weighed.
5) After 24 hours, they were reweighed, and any difference in weights recorded.
Results:
• Untreated (control) plant had most water loss, followed by upper epidermis
covered, lower epidermis covered, and both sides covered.
• This suggests that plants lose water through their stomates, and that leaves
have more stomates on their underside. This is because stomates on the
underside of a leaf are less exposed to the sun than stomates on the upper
epidermis, so having stomates on the underside of a leaf minimises water
loss by evaporation.
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9.2 Maintaining a Balance
Contextual Outline
Multicellular organisms have specialised organ systems that are adapted for the uptake and transport
of essential nutrients from the environment, the utilisation or production of energy and the removal
of waste products arising from cellular activities.
The basis of healthy body-functioning in all organisms is the health of their cells. The physical and
chemical factors of the environment surrounding these cells must remain within narrow limits for
cells to survive. These narrow limits need to be maintained and any deviation from these limits must
be quickly corrected. A breakdown in the maintenance of this balance causes problems for the
organism.
The nervous and endocrine systems in animals and the hormone system in plants bring about the
coordinated functioning of these organ systems. They are able to monitor and provide the feedback
necessary to maintain a constant internal environment. Enzyme action is a prime example of the need
for this balance. Enzymes control all of the chemical reactions that constitute the body’s metabolism.
As enzymes normally function only within a narrow temperature range, even small rises in body
temperature can result in failure of many of the reactions of metabolism that are essential to life.
This module increases students understanding of the applications and uses of biology, implications
for society and the environment and current issues, research and developments in biology.
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9.2 – Maintaining a Balance:
1. Most organisms are active within a limited temperature range:

Identify
the
composition
role
and
use
of
a
enzymes
simple
in
metabolism,
model
to
describe
describe
their
their
chemical
specificity
in
substrates:
–
Metabolism is the sum total of all chemical reactions occurring within a living organism. The only reason you
grow, heal etc is because of this. It is divided into two parts:

Anabolic: are reactions that involve the building up of larger organic compounds from simple molecules, eg
large polysaccharide molecule such as starch being made from monosaccharide units such as glucose (product
of photosynthesis).

Catabolic: are reactions that involve the breaking down of complex organic compounds to simple ones, eg
digestion of food, large food molecules such as proteins are broken down into small amino acids, which can be
used for other uses.
–
All the above, ie every metabolic reaction in your body is carried out by enzymes, they are organic protein
catalysts (chemical substance that speed reactions without taking part in it).
–
Chemical composition of enzymes:

Recall: proteins are made of polypeptides which in turn are made of amino acids.

All enzymes are made of protein as well as other elements that are known as co-enzymes/co-factors which help
specific enzymes function, such as carbon, hydrogen, oxygen and nitrogen.

Enzymes are globular proteins, meaning the polypeptide chains (ie amino acids) are folded into a 3-dimensional
globular shape.

This shape is what effective gives each enzyme its function, and parts of it are called active sites. The molecule
on which an enzyme acts on is called the substrate.
–
Specificity of enzymes:

Enzymes are highly specific in their action; this means that each enzyme acts on one substrate only, this is
because the shape of the active site of the enzyme matches the shape of the substrate material.

The products are the substances that the substrate(s) become. One substrate can be split, or two substrates can be
joined.
–
Models to explain specificity:

There are two current hypothesis:
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 The Lock and Key Model: suggests that the substrate fits exactly into the active site of the enzyme like a key
fits into a lock. It assumes that the enzyme had a rigid and unchanging shape.
 The Induced Fit Model: states that the binding of the substrate to the enzyme ‘induces’ a temporary change in
shape of the enzyme. The new shape of the enzyme better accommodates the shape of the substrate and a
reaction occurs.

Identify the pH as a way of describing the acidity of a substance:
–
pH is a way of describing the acidity or the alkalinity of a substance, its a measure of the concentration of
hydrogen ions per litre of solution, so the more acidic a substance is, the more hydrogen ions, the LOWER the pH.
–
The pH scale is from 0 to 14: a pH of 7 is neutral (pure water); above 7 is alkaline and below 7 is acidic.
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
Identify data sources, plan, choose equipment or resources and perform a
first-hand investigation to test the effect of increased temperature, change
in pH and change in substrate concentrations on the activity of enzymes:
–
Aim: To test the variety of factors (such as temperature, pH (acidity/alkalinity), substrate concentrations) on the
effect on enzyme activity.
–
Equipment:

Potato pieces/living tissue (ie cow liver pieces) (both contain the enzyme catalyse)
 Catalyse is a enzyme that breaks poisonous hydrogen peroxide into harmless water and oxygen gas

20 test-tubes

Hydrogen peroxide (H2O2)

Acid: H2SO4, Base: NaOH

Source of heat (ie hot plate)

pH probe

Thermometer
–
Safety:

Hydrogen peroxide is an extremely poisonous substance, it must not be ingested, and teacher supervision is
needed.

Hot plate can reach temperatures well over 200-400 degrees, it must be put in a rigid and safe position.

Gloves and glasses must be worn, in case of accidental test-tube damage.
–
Method:

3 separate tests were carried out in test tubes with potatoes placed in them; pH, temperature, substrate
concentration.

Evidence for enzyme activity came from the sound of 'fizzing effect', the louder the more activity is presumed.

This is further determined by the 'formation of bubbles', where bubbles that are in greater in height show greater
activity.
–
Result:
–
pH:

Each enzymes work best at its optimum pH, which is usually within a very narrow range, for example enzymes
in the stomach can work at 1-2 pH , whilst enzymes as catalase work at 7 pH.

Extremes of acidity or alkalinity can affect the bonds holding the 3D globular shape of the enzyme. Thus losing
activity and distorted.
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–
Temperature:

As temperature increases, MOST enzyme activity increases, up to the optimum temperature (a particular
temperature, approx. 40°C, an enzyme is most active). This is because the enzyme and substrate molecules
move faster as (more kinetic energy) and therefore more collisions between enzyme and substrate occur.

At very high temperatures, the activity of the enzyme falls rapidly, because the heat energy breaks the bonds
that cause the protein to fold, so destroying the active site in a irreversible process, called denaturation.
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–
Substrate concentration:

An increase in substrate concentration will increase the reaction until all enzyme active sites are occupied this is
known as saturation point, thus reaction proceeds at maximum rate (VMax or Maximum velocity). A further
increase in substrate, cannot increase the rate because the are no active sites available.

Explain why the maintenance of a constant internal environment is important
for optimal metabolic efficiency:
–
Metabolism is severally affected by enzymes, and hence the functioning of an organism. Enzymes work best
within a limited range of environmental conditions, but their efficiency is affected greatly by certain factors which
include temperature, pH and substrate concentration.
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–
Hence a constant and stable internal environment is needed so that enzymes will always be working at an optimum
rate, and thus metabolism will be a optimum efficiency, if these factors do not remain relatively stable then the
rate of enzyme-catalysed reactions decrease, this rate could affect an entire metabolic pathway.

Describe homeostasis as the process by which organisms maintain a relatively
stable internal environment:
–
Homeostasis is the process by which organisms maintain a relatively stable (constant) or almost constant, internal
environment.
–
Homeostasis falls into 2 categories, depending if it is exothermic (doesn't produce own heat) or endothermic
(produce own heat). An organism may be a conformer or a regulator.

Regulators try to maintain the parameter at a constant level over possibly wide environmental variations.

Conformers allow the environment to determine the parameter.

Explain that homeostasis consists of two stages
–
–
Detecting changes from the stable state;
–
Counteracting changes from the stable state:
Homeostasis in endotherms is carried out in 2 steps, this mechanism is known as feedback:

Detecting change.

Counteracting the change.
–
Detecting Changes:

Any change that provokes a response is a stimulus.

Receptors detect stimuli.
 Examples of external stimuli: light, day length, sound, temperature, odours.
 Examples of internal stimuli: levels of CO2, oxygen levels, water, wastes.

–
Receptors can range from a patch of sensitive cells, to complex organs like the eyes and ears of mammals.
Counteracting Changes:

After receptors detect changes, organisms can then react to the change.

This type of response will counteract the change to ensure the stable state is maintained.

Effectors bring about responses to stimuli.

Effectors can either be muscles or glands:
 Muscles bring about change by movement
 Glands bring about change by secreting chemical substances

Gather,
process
and
analyse
information
from
secondary
sources
and
use
available evidence to develop a model of a feedback mechanism:
–
The mechanism that brings about homeostatic change is called FEEDBACK
–
Homeostasis does not maintain the exact set point, but homeostasis is maintained as long as there is only a narrow
range of fluctuation (increase and decrease) of the variable around the set point. If the fluctuation is large (this is
the most common in humans), and exceeds the normal range, a negative feedback mechanism comes into
operation in response to this change; it is termed negative because it counteracts (negates) the change, thus
returning the body to within the normal range.
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–
In living organisms, the feedback system has 3 main parts:

Receptors: a type of sensor that constantly monitors the internal environment

Control Centre: receives info from the receptors and determines the response

Effector: Restores the set value. Keeps environments stable.
–
An example of a feedback system would be the control of carbon dioxide levels (an increase in it):

Outline
the
role
of the
nervous system
in
detecting
and responding
to
environmental changes:
–
The nervous system is an organ system containing a network of specialized cells called neurons that coordinate
the actions of an animal and transmit signals between different parts of its body.
–
The nervous system works to regulate and maintain an animal’s internal environment and respond to the external
environment, ie maintain homeostasis.
–
The nervous system is made up of two parts:
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
Central Nervous System: This acts as a CONTROL CENTRE for all the body’s responses and it coordinates
all these responses, it consists of the brain (specifically hypothalamus) and the spinal chord where it receives
information, interprets it and initiates a response.

Peripheral Nervous System: This is a branching system of nerves that connects receptors and effectors. This
system transmits messages from the central nervous system and back. It acts as a communication channel.

Identify the broad range over which life is found compared with the narrow
limits for individual species:
–
Ambient temperature literally means the temperature of the environment; room temperature implies a
temperature inside a temperature-controlled building (the building has specific parts which affect the ambient
temp).
–
Organisms on Earth life in environments with ambient temperatures ranging from less than 0ºC (such as arctic
animals) to more than 100ºC (such bacteria found in boiling undersea volcano vents).
–
However, individual organisms cannot survive this entire range of temperatures for example mammals can only
survive temperatures from about 0 - 45ºC.
–
This means that life is found in a very wide range of temperatures, but individual species can only be found in a
narrow temperature range.

Compare responses of named Australian ectothermic and endothermic organisms
to changes in the ambient temperature and explain how these responses assist
in temperature regulation:

Analyse
information
from
secondary
sources
to
describe
adaptations
and
responses that have occurred in Australian organisms to assist temperature
regulation:
–
Ectotherms (cold blooded): are organisms that have a limited ability to control their body temperature (due to
their cellular activities generate little heat). Their body temperatures rise and fall with ambient temperature
changes.

–
Most organisms are ectotherms; examples are plants, all invertebrates, fish, amphibians and reptiles.
Endotherms (warm blooded): are organisms whose metabolism generates enough heat to maintain an internal
temperature independent of the ambient temperature.

–
Examples are birds and mammals.
Ectothermic response; Central netted dragon (Ctenophorus nuchalis):

Increase in temperature (ie hotter):
 Stays in sheltered areas to avoid extreme heat. They can dig burrows or seek shelter in caves or crevices. This
reduces the effect of heat on their body.
 It can change into nocturnal animal when the temperature becomes very hot. Many desert animals sleep in
burrows during the day and are active at night, to escape the heat.

Decrease in temperature (ie colder):
 It will change its body position, to expose more of its body surface area to sun's rays, increasing core body
temperature.
 They will seek areas of higher heat rays, such as on top of ledges instead of burrows.
–
Endothermic response; Red Kangaroo (Macropus rufus):
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
Increase in temperature (ie hotter):
 It licks its arms to cool itself. The evaporation of the saliva cools its skin by convection.
 It becomes less active, activity generates heat as many reactions are exothermic (release heat).

Decrease in temperature (ie colder):
 Insulation: they have a thick fur layer, and contract their muscles controlling and shiver to generate heat.
 They seek group warming, where they are exposed to less cold air.

Identify some responses of plants to temperature change:
–
Since plants cannot move from environment to environment, they respond to temperature by various changes:
–
Increase in temperature (ie hotter):

Leaf orientation: Some plants can change the orientation of their leaves in relation to the sun at different times,
for example their leaves hang down vertically, to reduce exposure, thus controlling temperature.

Growth rates: They alter their growth rate for example; some Eucalyptus trees grow more in spring than in
winter, hence using less water which can be use for cooling itself.
–
Decrease in temperature (ie colder):

Deciduous trees (trees that shed their leaves for a part of every year) lose their leaves in winter (leaf fall) and
undergo a period of dormancy, which allows them to survive not only the extremely low temperatures, but also
water shortages and lower availability of sunlight.

Plants may die above the ground, but leave bulbs, roots, rhizomes or tubers to survive underground. These then
sprout when favourable conditions return.
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2.
Plants
and
animals transport
dissolved
nutrients
and
gases in
a fluid
medium:

Perform a first-hand investigation using the light microscope and prepared
slides to gather information to estimate the size of red and white blood
cells and draw scaled diagrams of each:
–
Aim: To estimate the size of red blood cells and white blood cells seen with a light microscope.
–
Equipment:

Light microscope

Prepared slides of human blood

1mm sized Mini-grid plastic paper

Pencil and drawing paper
–
Safety:

Slides can have sharp or unseen flint pieces of glass, gloves and glasses should be worn.

Use commercially prepared microscope slides of blood and not fresh blood, to eliminate the risk of contracting
blood-borne disease.
–
Method:

The microscope on normal view ie 1X, has a limited field of view of 16mm.

Hence set your microscope with the millimetre-squared graph paper first. Then 'click' the 1X objective lense,
this will show you what the 'normal' eye of 16mm can see.

Then click the 10X objective, this will magnify the 10mm by a factor of 10. Hence now youll see a maximum
field of view of 1.6mm, and its sub-ten components. (also note 1mm= 1000µm)

Now using the 40X objective, this now makes the initial 16mm diameter four times less then the 10X, so the
diameter is approximately 0.4mm. Hence this diameter is 0.4mm, or 400µm
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
Now, putting a slide of a prepared blood, at 40X objective, estimate how many blood cells there exists in that
'field of view', approximately 50 red blood cells exist, hence the size of 1 RBC is 400 µm divided by 50
(400/50), which is 8 µm.

Now for white blood cells since there are so few of them, it is NOT possible to count the number of white cells
across the diameter, and even much more difficult to estimate how many would fit across the diameter. Hence
there size is estimated by proportion in comparison to that of RBC.
– Result:

Red blood cells (Erythrocytes):
 Size: 6-9 µm
 Shape: Bi-concave (concave on both side) discs
 Function: Transport of oxygen.
 They have no nuclei; they only live for 3 months. After this they are destroyed in the liver
or spleen.
 5-6 million in every millilitre of blood.
 They are produced in the bone marrow

White blood cells (Leucocytes):
 Size: 12-15 µm
 Shape: Irregular shape; can change shape
 Function: To defend against disease
 Only 4-12 thousand per millilitre of blood
 They have nuclei, unlike red blood cells
 They are produced in the lymph glands.

Identify the forms in which each of the following is carried in mammalian
blood:
–
Carbon Dioxide
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–
–
Oxygen
–
Water
–
Salts
–
Lipids
–
Nitrogenous wastes
–
Other products of digestion
Carbon dioxide:

It is produced as a waste product of respiration in body cells. As its concentration is higher in the cell than in the
blood its diffuses in the blood:
 70% of the carbon dioxide is converted into carbonic acid then changed into hydrogen carbonate ions. This
change from carbon dioxide to carbonate ions happens on the red blood cells. The ions are transported in the
plasma, NOT dissolved in it.
Carbon + Water
Dioxide
CO2
+
Carbonic
Acid
H2O
Hydrogen +
Ions
H2CO3
Hydrogen
Carbonate Ions
H+ + HCO-
 Bind to haemoglobin in erythrocytes forming carbaminohaemoglobin (only 23% of the carbon dioxide).
 Be dissolved directly in the plasma (only 7% of the carbon dioxide).
–
Oxygen:

Oxygen is needed in the body for respiration. It is brought in across the respiratory surfaces of the lungs.

It binds with haemoglobin in red blood cells, forming oxyhaemoglobin.
–
Water:

Water is the solvent of plasma; it makes up the bulk of blood volume.

It makes up 60% of the volume of blood.
–
Salts:

These are transported directly dissolved in the plasma as ions (ie NaCl as Na+ and Cl-), these are known as
electrolytes.
–
Lipids and other products of digestion:

The aim of digestion is to break large molecules down to a size small enough for absorption through the
intestine wall and into the bloodstream, so that they can be transported to cells in the body where they are
required.
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
Lipids are any of a group of organic compounds (ie containing carbon), including the fats, oils, waxes, sterols,
and triglycerides that are insoluble in water, are oily to the touch, and together with carbohydrates and proteins
constitute the principal structural material of living cells.
 Digested lipids are changed into triglycerides (this happens in the lining of the small intestine).
 Lipids are then transported as chylomicrons (these are clusters of triglycerides, phospholipids and
cholesterol), wrapped in a coat of protein.
 These are released into the lymph and eventually pass into the veins
–
Other products:

Nitrogenous wastes:
 Wastes such as ammonia are changed in urea
 Urea is transported dissolved in the plasma

Minute minerals:
 Includes amino acids, sugars and vitamins
 They are mainly water soluble and transported in the plasma.

Explain the adaptive advantage of haemoglobin:
–
Haemoglobin is a protein made up of four polypeptide chains (called globins) and each is bonded to a haem
(iron-containing) group which can attach to an O molecule, forming oxyhaemoglobin.
–
For every haemoglobin, 4 oxygen molecules can attach. There about 250 million molecules of haemoglobin in
each red blood cell, hence the very high oxygen carrying capacity.
–
If blood carried oxygen without haemoglobin, the oxygen would have to be dissolved directly into the plasma
(into water). But oxygen is not very soluble in water therefore, if oxygen was carried only by being dissolved in
blood plasma, 100 ml of water would only be able to carry 0.2 ml of oxygen.
–
The presence of haemoglobin increases the oxygen carrying capacity of blood by 100 times

Dissolved only

Haemoglobin
–
0.2 ml O2/ 100 ml blood
20 ml O2/ 100 ml blood
The adaptive advantage:

It increases the oxygen carrying capacity of blood (proven above). Mammalian cells need a lot of energy and
therefore must have a continual supply of OXYGEN for RESPIRATION; this ability of blood to carry large
quantities of oxygen gives mammals a considerable survival advantage. The extra energy allows mammals to be
active, as well as grow large.
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
It has the ability to bind oxygen at an increasing rate once the first oxygen molecule binds to it. The bonding of
each oxygen molecule causes the haemoglobin to change slightly in shape, making it easier for every subsequent
oxygen molecule to bind to it. This increases the rate and efficiency of oxygen uptake. As a result, a very small
increase in the oxygen concentration in the lungs can result in a large increase in the oxygen saturation in the
blood.

It has the capacity to release oxygen at an increasing rate when carbon dioxide is present. Metabolising cells
release carbon dioxide, which combines to form acidic carbonic acid, and this lower pH, thus increases chances
to affect enzymes, and toxicoses cells (acid is corrosive).

It can undergo the Bohr effect, which at lower pH (due to increasing CO2) levels can release oxygen to tissue
areas that in need of it.

Outline the need for oxygen in living cells and explain why the removal of
carbon dioxide from cells is essential:
–
Cells require oxygen in the process of respiration:

–
Glucose + oxygen
carbon dioxide + water + energy (in the form of ATP).
Carbon dioxide is a waste product and must be removed to maintain the normal pH balance of the blood. By
removing excess carbon dioxide, it prevents a build up of carbonic acid, which causes the lowering of the pH, and
therefore increasing breathing rate and depth. Carbonic acid forms when carbon dioxide dissolves in water. At
normal levels, the carbon dioxide; bicarbonate ion (HCO3-) equilibrium is an important mechanism for buffering
the blood to maintain a constant pH, if greater amounts of carbon dioxide are produced the body cells (blood and
lymph) will become acidic, enzymes can only function within a specific pH range, therefore an increase in carbon
dioxide will result in lowering the pH which will affect the overall metabolism of the body.

Perform a first-hand investigation to demonstrate the effect of dissolved
carbon dioxide on the pH of water:
–
Aim: To model the effect of carbon dioxide on the pH of water.
–
Equipment:

25ml of Distilled water in 100mL beaker

Universal indictor (its an indicator that changes colour depending on the pH of a solution)

pH probe attached to data logger
–
Safety:

Gloves and glasses should be worn, in case of glass breaking.

The water can become corrosive due to increasing pH, it should NOT be ingested after use, dispose in an
organic waste container.

–
Straws should NOT be used by more then one student, to minimise contracting diseases.
Method:
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
In a beaker, pour water till the 25mL grade mark, then put 3 drops of universal indicator, this should now
change into greenish colour.

Then put the pH probe, and check the pH is about 7.

Exhale air into the straw that is dipped into the solution, for about 3 minutes.
–
Result:

After about 30 seconds, the colour of the solution began to change into pale yellow, and the pH on the data
logger started decreasing.

This is because carbon dioxide forms a weak acid; carbonic acid (H2CO3) so the water becomes more acidic.
Carbonic acid in water dissociates to form hydrogen carbonate ions (HCO3-), and some carbonate ions (CO32-).

Analyse information from secondary sources to identify current technologies
that
allow
measurement
of
oxygen
saturation
and
carbon
dioxide
concentrations in blood and describe and explain the conditions under which
these technologies are used:
Technology
Pulse
oximeter
How it Works
The Conditions It Is Used
Measures O2 levels ONLY.
Used in many conditions; this is because it is
Device like a peg sits on the finger and
painless, easy to apply and quick to give results,
measures the transmission of light through
example:
tissues ie measures the amount of oxygen in

arterial blood.
anaesthesia.
There is a large difference between red light

absorbed by haemoglobin compared to
oxyhaemoglobin, hence this can be analysed
gas (ABG)

analysis
Measures
pressure

(or
the
concentration) of O2 and CO2 in the
Used when there are signs of dangerously low
oxygen or high carbon dioxide levels.

blood
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Can be used as a general check-up procedure to
analyse O2 levels
Measures O2 and CO2 levels.

Monitor premature babies that are in neo-natal
wards.
to give a reading.
Arterial blood
During surgeries, to monitor patients under
Helpful
for
monitoring
patients
under
anaesthesia, in intensive care, in accident or
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
emergency facilities and for premature babies.
Measures saturation of oxygen (which is
the amount of oxygen combined to
haemoglobin
compared
to

the
maximum)

Helps for diagnosing as well as monitoring
patients eg a patient in a coma can have their
blood gases regularly monitored.
Measures levels of bicarbonate and pH
(to show CO2 levels)
This analysis evaluates how effectively the
lungs are delivering oxygen and removing
carbon dioxide.

Compare the structure of arteries, capillaries and veins in relation to
their function:
Arteries
Veins
Structure
Thick walled, elastic, muscular
Thinner walls then arteries, elastic, less
muscle , wider diameter (larger lumen)
Direction of blood:
flow / pressure
Carry blood away from heart, pressure
created by hearts pumping puts stress on
arteries, blood pressure is high
Contain muscle fibres which contract and
relax, rate is maintained as blood travels in
spurts towards body tissues
Oxygenated blood taken away from heart
Carry blood to heart, as there is no stress on
veins the blood pressure is low
Diagram
Blood movement and
rate
Carries
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Contain no muscle, rely on valves and when
large muscle contract they help push the blood
flow through the veins
Deoxygenated blood taken to the heart
Page 17 of 37
–
Capillaries:

Capillaries are an extension of the inner layers of the arteries and veins (Artery  arterioles  capillary 
venules  veins).

Capillaries are only one cell thick, and are so narrow, that only one red blood cell can pass at a time.

Capillaries surround all tissue cells, thus they provide a very large surface area over which exchange of
materials between blood and body cells can occur.

Describe the main changes in the composition of the blood as it moves around
the body and identify tissues in which these changes occur:
–
Pulmonary circuit (From Body to HEART to the Lungs):

Blood enters the right atrium of the heart via the vena cava (major vein):

The blood is deoxygenated, and high in carbon dioxide.
 It is also low in glucose and other nutrients; high in urea, other nitrogenous wastes and various poisons.

As the heart beats, the right ventricle pumps the blood through the pulmonary artery, to the lungs:

Here the blood gains oxygen through exchange with alveoli in the lungs (ie air sacs), and loses its carbon
dioxide.

The blood then enters the left atrium via the pulmonary vein.
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–
Systemic circuit (From Lungs to HEART to the Body):

The left ventricle pumps oxygenated blood to the body through the aorta.

In the body, various changes occur to the blood.

The blood loses oxygen and gains carbon dioxide in all body cells, as respiration occurs.

In the Liver:
 Levels of glucose are regulated: excess glucose is changed to glycogen, or glycogen stores are changed to
glucose (if needed).
 Excess amino acids are changed to ammonia, and then to urea.
 Poisons are also reduced, as the liver changes them to less toxic forms.

In the Intestines:
 Levels of nutrients from digestion increase.
 Glucose, amino acids, ions, lipids and other substances from food enter the blood.

In the Kidneys:
 Salt and water levels are regulated.
 All urea is removed, toxins are excreted into the urine.


The changed blood, again highly deoxygenated, from the body then flows back to the pulmonary circuit.
Analyse information from secondary sources to identify the products extracted
from donated blood and discuss the uses of these products:
–
Red blood cells:

Used to increase the amount of oxygen that can be carried to the body’s tissues; given to anaemic patients, or
people whose bone marrow do not make enough red blood cells
–
Plasma:

This liquid portion of the blood, is given to people with clotting disorders (such as haemophilia), and also used
to adjust the osmotic pressure of the blood (to pull fluids out of tissues).
–
White blood cells:


Infection fighting component of the blood.
Analyse and present information from secondary sources to report progress in
the production of artificial blood and use available evidence to propose
reasons why such research is needed:
– The problems of using real blood:

Shortage of real blood

It has to be ‘cross-matched’. This is because, if you receive the wrong type of blood, it can be fatal. This is a
great disadvantage in emergency situations.

It has to be free of infectious agents. Only blood that is free of bacteria and infectious agents (such as HIV) can
be used. Testing the blood is costly.

It has a short shelf-life. Because red blood cells only survive for 3 months, the blood has a short life span (blood
can only survive for 3-4 weeks).
– Proposed replacement; Perflurochemicals (perflurocarbons):
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
Synthetic and inert, are completely sterile

Cheap to produce, compared to using real blood.

Can dissolve 5 times more oxygen than blood.

Free of biological materials, therefore no risk of infections

BUT; must be combined with other materials to mix in with the bloodstream (eg lecithin).

Choose
equipment
gather
first-hand
or
resources
data
to
to
draw
perform
transverse
a
first-hand
and
investigation
longitudinal
sections
to
of
phloem and xylem tissue:
–
Aim: To draw the transverse (top view) and longitudinal section (side view) of plant tissue (ie xylem and phloem).
–
Equipment:

A stick of celery

Red food colouring

Water in a 100mL beaker

Razor blade

Light microscope
–
Safety:

The razor blade is extremely sharp, gloves should be worn incase of accidental flicking of blade onto skin.

Glasses should be worn incase of glass breaking.
–
Method:

In the 100mL beaker filled with water, put 3-5 drops of red food colouring into the solution. It should change to
dilute red colour.

Place the celery stick into the beaker, and leave it over night, so the coloured water can seep into the plant
sections to rise through xylem vessels, hence staining them strongly. Some water also travelled down the
phloem vessels.

Using a sharp one-sided razor blade, very thin slices were cut from across the stalk (for the transverse section)
and from the length of the stalk (for the longitudinal section).

–
Suitable slices were then prepared as wet mounts and viewed under a light microscope.
Result:
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
Phloem:
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

Xylem:
Describe current theories about processes responsible for the movement of
materials through plants in xylem and phloem tissue:
–
There are 2 types of transport tissues in plants:

Xylem: This transports water and mineral ions upwards from the roots to the leaves of a plant.

Phloem: This transports organic materials (particularly sugars) up and down the stem to other parts of the plant.
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–
There exist two theories (ie possible explanations based on evidence) into how water/nutrient moves in each tissue
respectively.

In Xylem:
 The transpiration stream theory (ie cohesion-adhesion-tension theory) possists that due to physical forces of
water (and ions) being removed from the plant stomates by passive transport (ie transpiration), causes a
column of water to be sucked up into the stem by the evaporative pull, also the low concentration of water at
the roots allows more water to diffuse in.
 Once water has been absorbed into the roots of plants (by osmosis) along with mineral ions (by diffusion and
active transport), these substances move across the root into the xylem. A small amount of root pressure
results from the continual influx of more water and ions, hence forcing the solution already present upwards
(due to pressure build up), however this is usually not enough.
 The constant loss of water, leads to a transpiration stream (which is the constant upward flow of water
through a plant), this is because of waters 2 properties, which are adhesive forces (the ability of molecules to
attach to walls), and cohesive forces (the attraction of molecules to each other), hence leading to the
capillarity (water rising up through bore of tissue) and hence the stream.

In Phloem:
 The pressure flow theory (ie source-path-sink theory) states that in the plants, there are sources of nutrients,
e.g. leaf cells are the sources of sucrose. As the sucrose, amino acids and other minerals build up, the cells
actively transport the glucose sugars by active transport into the phloem tubes, this is known as loading, it
can be done by 2 ways:

Symplastic Loading: Sugars and nutrients move in the phloem from the mesophyll cells to the sieve
elements through the plasmodesmata that join adjacent cells (note: Plasmodesmata have not been found in
all plants).
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
Apoplastic Loading: sugar and nutrients move along the cell walls to the sieve plate. Then they cross the
cell membrane by active transport to enter the phloem tube.
 As sugars enter the phloem the concentration of phloem sap increases, this causes the entry of water by
osmosis from the surrounding cells (osmotic pressure gradient is low). This resulting pressure causes water
and dissolved solutes to flow towards a SINK.
 A sink is a region of the plant where sugars and other nutrients are actively begin removed from the phloem.
As sugars move out of the phloem, water flows out with them. This reduces the pressure in the sieve cells at
the sink region.
 Materials are transported both up and down the stem and are distributed especially to the growing points and
reproductive structures, including developing fruits and seeds, it is driven by a gradient generated osmotically.
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3. Plants and animals regulate the concentration of gases, water and waste
products of metabolism in cells and in interstitial fluid:

Explain why the concentration of water in cells should be maintained within
a narrow range for optimal function:
–
Water makes up around 70-90% of living things; it is essential for life, it is the solvent of all metabolic reactions in
living cells (universal solvent), and sometimes directly takes part in it (eg. respiration). Therefore a deviation can
cause:

Isotonic: Concentration of solutes outside the cell is the same as inside the cell. No overall movement of water.

Hypertonic: Concentration of solutes is greater outside the cell than inside. Water tends to move out of the cell.

Hypotonic: Concentration of solutes is greater inside the cell than out. Water tends to move inside the cell.
–
Living cells work best in an isotonic environment where the levels of water in cells need to be kept relatively
constant, any change in the concentration of solutes will result in a change in the levels of water in cells which
usually results in death (either dehydration or cell bursting)
–
Enzymes also require specific conditions of functioning, some of which could relate to the levels of water and
solutes in cells, as an increase in water changes the concentration of acid (either dilutes it or makes it
concentrated).

Explain why the removal of wastes is essential for continued metabolic
activity:
–
As a result of metabolism, many waste products are formed, for example:

In the process of deamination (process by which amino acids and proteins are broken down into ammonia),
ammonia is highly toxic and must be removed or changed to a less toxic form. It can greatly increase the pH and
make it more alkaline.

–
It carbon dioxide acculmates, it can form carbonic acid, which lowers the pH.
If these toxins are allowed to accumulate, they would slow down metabolism and kill the cells (e.g. excess toxins
is acidic thus increases pH, affection enzyme function which can lead to denaturation), this is why they need to
quickly be removed, or converted into a less toxic form.
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
Identify the role of the kidney in the excretory system of fish and mammals:
–
The maintenance of a constant concentration of nutrients, water and waste products in the internal environment of
organism, is crucial to its wellbeing. The concentration of these substances directly affects metabolism in cells,
and hence needs to be balanced.
–
Many wastes are excreted (process by which waste products, which have been produced as a result of metabolism,
are removed from the body). The excretory system is made up of systems and organs that carry out the removal of
metabolic wastes.

Carbon dioxide is excreted via the lungs (ie respiratory system).

Nitrogenous wastes are removed along with excess salts and water via the kidneys (ie urinary system).
–
The kidney is an organ of the excretory system of both fish and mammals. It plays a central role in homeostasis,
forming excreting urine while maintaining osmoregulatory.
–
Osmoregulation: means the physiological processes that an organism uses to maintain water balance; that is, to
compensate for water loss, avoid excess water gain, and maintain the proper osmotic concentration (osmolarity) of
the body fluids.

Distinguish
between
active
and
passive
transport
and
relate
these
to
processes occurring in the mammalian kidney:

Explain how the processes of filtration and reabsorption in the mammalian
nephron regulate body fluid composition:
–
Active transport: is the process of using energy to transport substances across highly concentrated membrane
from an area of low concentration, it would normally not be able to cross due to a concentration gradient (the
amount of substance in a particular area).
–
Passive transport: is the process of movement substances across a membrane from an area of higher
concentration to an area of lower concentration without energy expenditure (this is diffusion and osmosis).
–
The excretory system is a group of organs that function together remove metabolic wastes from the tissues of an
organism and expel them to the outside, a kidney is the main excretory organ responsible for removing
nitrogenous wastes from the bodies of vertebrate animals (including fish and humans).
–
The function of the kidney in excretion is to filter the blood that enters it, removing the waste in the blood
solution, for this waste to be excreted. This filtration is carried out by millions of small filtering units that are in
kidneys which are known as nephrons.

The nephron is a regulatory unit; it absorbs or secretes substances in order to maintain homeostasis, this
regulation maintains the constant composition of body fluids which is done by adjusting salts and water levels to
maintain fluid concentration, different ions also adjusted to maintain pH.
–
Urine is the final solution produced by these microscopic tubules, and passes out the kidney via ducts (ureters) and
then goes to the urine storage organ (bladder), which after a certain limit fills and the human passes this urine
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through the urethra to the outside. (In vertebrates this goes to the a chamber (cloaca) instead of the urethra, which
empties to the outside)
–
Detailed structure of a nephron:

It consists of 4 parts (in order of movement) THAT are heavily surrounded by capillaries: Bowmans capsule
Proximal (ie first) convoluted tubule
the loop of Henle
Distal (ie second) convoluted tubule
collecting duct which produces urine that leads to the bladder.
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–
Function of nephrons

Three main process occur in the kidney, in the parts mentioned above, they are filteration
reabsorption
secretion.

Filtration:
 When highly oxygenated, unfiltered blood enters the kidney through the renal artery it goes to the nephrons,
upon reaching it splits into a spherical network of blood capillaries called glomerulus that are in a Bowman's
capsule, the blood pressure here is so high that fluid and substance from the blood are forced into the
Bowman’s capsule, and forms a fluid called the glomerular filtrate.
 Blood cells and proteins are retained in the blood, while large volumes of water pass through contained
dissolved substances such as: water, amino acids, glucose, salts (ions), nitrogenous wastes and other toxic
molecules.
 This process is known as filtration, it separates based on SIZE of molecules, since proteins and RBC are
larger then other molecules they cannot pass the Bowmans capsule. Therefore:

Substances that the body needs will require reabsorption, so they are not lost with urine.

Additional wastes that were in the bloodstream, and managed to escape the higher pressure of the Bowmans
capsule need to be added to this 'urine' mixture.
 Hence this is not the final fluid excretion.
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
Reabsorption:
 Depending on the feedback of the body, varying amounts of solutes are reabsorbed from the solution, for
example water, amino acids, glucose, salts (Na+, K+, Cl-, Ca2+, Mg2+, HCO3-).
 This occurs in the proximal, loop of Henle and distal tubules.
 In the proximal tube:

All organic nutrients (amino acids and glucose) are reabsorbed, aswell as some ions such as (Na+, K+, Cl-,
Ca2+, Mg2+, HCO3-).
 In the loop of Henle:

After the initial reabsorption from the distil tube, you'll have a liquid that is primarily urine, whether its
concentrated or not, is dependent in the loop of Henle.

The loop of Henle has 2 limbs, a descending then ascending, where the descending is permeable to water
ONLY, and the descending is permeable to salt ONLY.

Secretion:
 This is the last process and leads to the formation of urine. It occurs in the distil and collecting tubule.
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 The liquid present in the tubule, are then added with metabolic wastes (such as urea, ammonia, hydrogen ions,
durgs: pencillin, morphine) etc that are brought by active transport to the distil tubule.

Explain
why
the
processes
of
diffusion
and
osmosis
are
inadequate
in
removing dissolved nitrogenous wastes in some organisms:
–
Diffusion and osmosis are both examples of passive transport (ie they do not require energy), this is too slow for
the normal functioning, because the movement of molecules relies on differences in the concentration gradient
between two solutions (it moves from high conc. to low conc.)
–
Also this process greatly slows down once the difference in concentration gradient becomes smaller, and stops
once the concentrations are at equilibrium.
–
Further problems with:

Diffusion:
 Toxins such as drugs can accumulate in the body, and can only be removed if they are in water, hence they
would ONLY move if there was a higher concentration of toxins in the blood then the urine itself. And this
would stop if the concentrations equalise.

Osmosis:
 Too much water is lost in urine: If there is a high concentration of urine, water will continually be drawn from
the body to even out the conc. gradient. However, excretion of dilute urine means the loss of large amount of
water from body, a loss to great for terrestrial animals.
 Osmosis only deals with the movement of water and thus would only allow water to move out of the body,
not the nitrogenous wastes.

Perform a first-hand investigation of the structure of a mammalian kidney by
dissection, use a model or visual resource and identify the regions of the
mammalian kidney involved in the excretion of waste products:
–
Aim: To identify the regions of the mammalian kidney, notably the ones involved in the excretion of waste
products.
–
Equipment:

One commercially packed cow (mammalian) kidney

One sharp medical cutting scalpel

Dissecting tray

Clean 'laying' paper

Latex gloves

Tissue forceps (they are things that help pull skin)

Disinfecting agent
–
Safety:

Gloves and protective face masks are crucial, incase of a diseased kidney, or the possible contracting of a
disease between touching.

Gloves are also crucial in handling of sharp object, incase of accidental damage.
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
Disinfecting agent was used on the tray, and the paper, incase of airborne particles that may be ingested and
cause allergies or disease.

–
Material was carefully disposed, to inhibit the build up of bacteria and other organisms.
Method:

Carefully layer brush the tray with agent, and paper, and place them together.

Place the kidney facing sideways, and carefully cut sideways to obtain a 'longitudinal' cut (ie sideway cut), using
forceps to open the skin.
–
Result:

The kidney is made up of 3 sections, the pelvis, the medulla and the cortex, the obvious observable sections
where located, and an imaginary "large" nephron was placed, to observe where the 3 mains process (ie
filteration
reabsorption
secretion) occur.
 Cortex:

Contains the glomeruli. It is very dark red due to the capillaries

It is involved in the filtration of blood.
 Medulla:


Contains the nephron tubules, as can be observed by the striped appearance of the medulla

It is involved in the reabsorption and secretion of substances
Pelvis:


It is where all the collecting ducts connect to, ie the collecting of urine.
Gather, process and analyse information from secondary sources to compare
the process of renal dialysis with the function of the kidney:
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–
People with disfunctional kidneys are not able to remove wastes such as urea, they have to undergo renal dialysis
to regulate their blood.
–
Renal dialysis is an artificial process in which waste in the blood are removed by diffusion across a partially
permeable membrane of solution known as dialysis fluid. It is a solution of salts, glucose, dissolved gases and
other substances (it has an equivalent composition to interstitial fluid), wastes (particular urea and excess salts),
diffuse out of the blood into the dialysis fluid. The clean blood is then returned.
–
The process:

The blood is extracted from the body from a artery (as it has come from the heart with oxygen, and going to
body to pass its waste and regulate levels etc, but it cant as kidney has failed hence blood from artery is used)
and passed into a dialyser, which is is a medical unit which is a bundle of hollow fibres made of partially
permeable membrane to help units suffering from artery failure.

The dialyser is in a solution of dialysing fluid, which has similar concentrations of substances as blood.

The dialyser only allows wastes to pass through, and not blood cells and proteins (in this way it is similar to the
filtrations stage of the nephron).
–

The wastes diffuse into the solution, and it is constantly replaced

The anti-clotting agent, heparin, is also added to prevent clotting.

The blood is then returned to the body via a vein.
Comparison of dialysis and normal kidney function:
Kidneys
-
Continuous process; very efficient
Renal Dialysis
-
Slow process; occurs a few times a week for
patients
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-
Active and passive transport is used throughout
-
Only passive transport is used
-
Useful substances are not reabsorbed as they
the nephron
-
Useful substances are reabsorbed actively by
the kidney
-
diffuse into blood from dialysing fluid
Uses a series of membranes (nephrons) which
-
are selectively permeable.

Outline
the
role
of
Also uses membranes (but artificial) which are
selectively permeable.
the
hormones,
aldosterone
and
ADH
(anti-diuretic
hormone) in the regulation of water and salt levels in blood:
–
Recall:

Dehydration is defined as an excessive loss of body fluid.

Blood volume is the volume of blood (both red blood cells and plasma) in a person's circulatory system. Blood
volume is determined by the amount of water and sodium ingested, excreted by the kidneys into the urine.
–
A hormone is a chemical released by one or more cells that affects cells in other parts of the organism. It is
essentially a chemical messenger that transports a signal from one cell to another, only a small amount of hormone
is required to alter cell metabolism. All multicellular organisms produce hormones however animals usually
produce hormones which are often transported in the blood.
–
The kidneys maintain constant conditions within the body by excreting wastes such as urea and by regulating the
amounts of water and salts that are reabsorbed. This aspect of homeostasis is mainly due to the actions of two
hormones: aldosterone and antidiuretic hormone (ADH):
–
ADH (Anti-Diuretic Hormone):

Also called vasopressin, anti-diuretic hormone literally means (anti-'water losing'), diuretic are heavily used in
pro-bodybuilding shows to lose water.

It controls the reabsorption of water, this is done by adjusting the permeability of the collecting ducts and the
distal tubules.
 Hence a release of it (ie increase levels), increases (sucks) water out from the tubules, hence the urine
becomes more concentrated (as less water is present).

It is made in the hypothalamus in the brain, but stored in the pituitary gland.

Receptors in the hypothalamus monitor the concentration of the blood:
 High Salt Concentration: ADH levels increased, collecting ducts and distal tubules become more permeable to
water, more water reabsorbed, concentration returns to normal. (Concentrated urine)
 Low Salt Concentration: ADH levels reduced, collecting ducts and distal tubules less permeable to water, less
water absorbed, concentration returns to stable state. (Dilute urine)
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
ADH does not control the levels of salt in the blood. It only controls the concentration of salt through water
retention.
–
Aldosterone:

Is a hormone that increases the reabsorption of sodium and the release (secretion) of potassium in the kidneys.
Hence a release of it (ie increase levels), causes more salts to be sucked out of the tubules.

Aldosterone is produced by the outer-section of the adrenal cortex in the adrenal gland, (which sits above the
kidney) and acts on the distal tubules and collecting ducts of the kidney.

When there is a lack of absorption of salts (ex. NaCl, NH3, K+ etc) , a signal goes to the hypothalamus which
triggers the secretion of aldosterone.
 High Salt Concentration: Aldosterone levels decreased, less salt reabsorbed, hence less water diffusing into
body cells.
 Low Salt Concentration: Aldosterone levels increased, more salt reabsorbed, more water diffusing into body
cells.

Present
information
to
outline
the
general
use
of
hormone
replacement
therapy in people who cannot secrete aldosterone:
–
This is a second developed technology, where the first was renal dialysis to aid people with affected kidneys.
–
Addison’s disease is a rare endocrine disorder occurring when the adrenal glands, seated above the kidney, fail to
produce enough aldosterone. Without aldosterone, the body would not be able to reabsorb salt (specifically sodium
ions) this would cause severe dehydration and excessive potassium loss which may cause brain damage and death.
–
The artificial replacement hormone is called Fludrocortisone, a drug that decreases the amount of salt the body
excretes. It is taken either orally or intravenously, patients are also advised by their doctors to increase their salt
intake.

Define
enantiostasis
as
the
maintenance
of
metabolic
and
physiological
functions in response to variations in the environment and discuss its
importance
to
estuarine
organisms
in
maintaining
appropriate
salt
concentrations:
–
Homeostasis is the process by which organisms maintain a relatively stable (constant) or almost constant, internal
environment.
–
Enantiostasis is the maintenance of metabolic and physiological functions in response to variations in the
environment.
–
The difference between the two, is the fact that homeostasis requires only a SPECIFIC internal condition for an
organism to function properly, example 37o is the required temperature for humans to function, enantiostasis is for
a VARIETY of internal condition which the function can function properly at, for example diving birds rely on
enantiostasis to function properly at extremely high and low pressure sky levels.

–
In homeostasis heat is 'acted against' by sweating etc, the pressure for birds isn't 'acted against'; it is 'adapted' to.
An estuary is where a freshwater river meets and mixes with saltwater sea, and as such the salinity levels are
always changing dramatically. This is determined by the tide of the sea:
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
At high tide: sea water flows into the river mouth, creating an environment with higher salt concentration, hence
this salt water has the tendency to draw water out cells by osmosis (as the organism will be in freshwater)

At low tide: sea water flows out of the river mouth, and freshwater from the estuary is abundant, hence by
diffusion organism face the challenge of water moving into their tissue.
–
Organisms living in such an environment need to have mechanisms to cope with such changes in order to survive,
this is collectively called enantiostasis.
–
Enantiostasis is carried out by 2 process (these are present in normal homestasis conditions too, but they carry out
different roles):

Osmoconformation: process by which organisms tolerate the changes in the environment, and conform, or alter
the concentration of their internal solutes to match the external environment. Their metabolism can handle it.


Osmoregulation: is the control of the levels of water and mineral salts in the blood.
Process and analyse information from secondary sources and use available
evidence to discuss processes used by different plants for salt regulation
in saline environments:
–
Salt, even in small concentrations, has a damaging effect on cell metabolism.
–
Halophytes are plants that adapted and can tolerate high salt levelled environments, they are commonly found in
areas such as estuaries.
Grey Mangroves (Avicennia marina):
–

Salt Prevention: In its roots, it has a layer of cells that actively restrict the movement of salt into xylem vessels.

Salt Exclusion: Special glands in the mangroves can actively exclude the salt from the water, so that the water
absorbed has a lower salt concentration than the water in the environment.

Salt Accumulation: Salt is accumulated in old leaves that drop off, so that the salt is out of the plant’s system

Salt Excretion: Salt can be excreted from the underside of the leaves of the mangrove plants; salt crystals form
under the leaves.

Describe adaptations of a range of terrestrial Australian plants that assist
in minimising water loss:

Perform a first-hand investigation to gather information about structures in
plants that assist in the conservation of water:
–
Aim: To gather information from plant specimens about structures that assist in the conservation of water.
–
Equipment:

Different type of leafs that exist around the school (typical environment)

Hand lens
–
Safety:

Sun has strong UV light outside, sunscreen and hats should be worn.
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
–
Leaf can be diseased and can have splinters and can be sharp, gloves should be worn.
Method:

Carefully, leaves where looked at for different 'prominent' features that could inhibit water loss, these where
then cross-checked with reliable sources.
–
Result:

Banksia:
 Leaves have sunken stomates: this reduces transpiration.
 Hard, waxy cuticles: this reduces the amount of water loss through transpiration.

Eucalyptus trees:
 Hard, waxy cuticles: this reduces the amount of water loss through transpiration.
 Leaves hang vertically: reduce sun exposure.

Spinifex grass:
 Have extensive root systems that can reach underground water.
 Leaves are also long and thin: to reduce water loss by transpiration.
 Can roll up to hide their stomata's: this reduces the amount of water loss through transpiration.

Analyse
information
from
secondary
sources
to
compare
and
explain
the
differences in urine concentration of terrestrial mammals, marine fish and
freshwater fish:
–
Freshwater Fish:

Osmotic Problem: Hypotonic to environment. Water diffuses INTO their bodies. Salts diffuses out.

Role of Kidney: Doesn’t drink continually, Kidneys removes excess water, while reabsorbing salts.

Urine: Large, dilute amount.
–
Marine Fish:

Osmotic Problem: Hypertonic to environment. Water diffuses OUT of their bodies. Salt diffuses in.

Role of Kidney: Continually drinks water, Kidneys reabsorb water, while actively secreting salts.
(Salt is also excreted across gills)

–
Urine: Small, concentrated amount.
Terrestrial Mammals:

Osmotic Problem: Water needs to be conserved.

Role of Kidney: Regulates concentration of blood, while at the same time excretes urea and conserves water.

Urine: Concentration changes with the availability of water, as well as temperature and water loss through
sweat. Water levels in blood rise, urine amount rises, and concentration decreases and vice versa.

Explain
the
relationship
between
the
conservation
of
water
and
the
production and excretion of concentrated nitrogenous wastes in a range of
Australian insects and terrestrial animals:
–
Ammonia is the direct result of amino acid breakdown (deamination) and is a waste product of all organisms. It is
very water soluble, but VERY toxic, and must be removed quickly, or changed to a less toxic form.
–
The removal of ammonia would require large volumes of water, and this is not possible for animals or insects that
seek to conserve water.
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
Aquatic Animals and Fish: These organisms directly release AMMONIA into the environment. This uses a lot
of water, but they have no need to conserve it. Ammonia is very water soluble and is excreted through the gills.

Terrestrial Animals: Releasing ammonia would be impossible due to lack of water. Instead, land-dwellers
change ammonia into less toxic forms and release it periodically. Mammals change it into UREA and release it
as urine (ex; kangaroos, wallabies, hopping mice and koalas). Australian animals release very concentrated
urine, and are able to tolerate high levels of urea in their bodies.

Birds: Birds change ammonia into URIC ACID, a whitish paste which uses hardly any water. This is lighter
than using urea, and helps in flight.

Insects: Insects also change ammonia to URIC ACID.
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9.2 Maintaining a Balance
Contextual Outline
Multicellular organisms have specialised organ systems that are adapted for the uptake and transport
of essential nutrients from the environment, the utilisation or production of energy and the removal
of waste products arising from cellular activities.
The basis of healthy body-functioning in all organisms is the health of their cells. The physical and
chemical factors of the environment surrounding these cells must remain within narrow limits for
cells to survive. These narrow limits need to be maintained and any deviation from these limits must
be quickly corrected. A breakdown in the maintenance of this balance causes problems for the
organism.
The nervous and endocrine systems in animals and the hormone system in plants bring about the
coordinated functioning of these organ systems. They are able to monitor and provide the feedback
necessary to maintain a constant internal environment. Enzyme action is a prime example of the need
for this balance. Enzymes control all of the chemical reactions that constitute the body’s metabolism.
As enzymes normally function only within a narrow temperature range, even small rises in body
temperature can result in failure of many of the reactions of metabolism that are essential to life.
This module increases students understanding of the applications and uses of biology, implications
for society and the environment and current issues, research and developments in biology.
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9.2 – Maintaining a Balance:
1. Most organisms are active within a limited temperature range:

Identify
the
composition
role
and
use
of
a
enzymes
simple
in
metabolism,
model
to
describe
describe
their
their
chemical
specificity
in
substrates:
–
Metabolism is the sum total of all chemical reactions occurring within a living organism. The only reason you
grow, heal etc is because of this. It is divided into two parts:

Anabolic: are reactions that involve the building up of larger organic compounds from simple molecules, eg
large polysaccharide molecule such as starch being made from monosaccharide units such as glucose (product
of photosynthesis).

Catabolic: are reactions that involve the breaking down of complex organic compounds to simple ones, eg
digestion of food, large food molecules such as proteins are broken down into small amino acids, which can be
used for other uses.
–
All the above, ie every metabolic reaction in your body is carried out by enzymes, they are organic protein
catalysts (chemical substance that speed reactions without taking part in it).
–
Chemical composition of enzymes:

Recall: proteins are made of polypeptides which in turn are made of amino acids.

All enzymes are made of protein as well as other elements that are known as co-enzymes/co-factors which help
specific enzymes function, such as carbon, hydrogen, oxygen and nitrogen.

Enzymes are globular proteins, meaning the polypeptide chains (ie amino acids) are folded into a 3-dimensional
globular shape.

This shape is what effective gives each enzyme its function, and parts of it are called active sites. The molecule
on which an enzyme acts on is called the substrate.
–
Specificity of enzymes:

Enzymes are highly specific in their action; this means that each enzyme acts on one substrate only, this is
because the shape of the active site of the enzyme matches the shape of the substrate material.

The products are the substances that the substrate(s) become. One substrate can be split, or two substrates can be
joined.
–
Models to explain specificity:

There are two current hypothesis:
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 The Lock and Key Model: suggests that the substrate fits exactly into the active site of the enzyme like a key
fits into a lock. It assumes that the enzyme had a rigid and unchanging shape.
 The Induced Fit Model: states that the binding of the substrate to the enzyme ‘induces’ a temporary change in
shape of the enzyme. The new shape of the enzyme better accommodates the shape of the substrate and a
reaction occurs.

Identify the pH as a way of describing the acidity of a substance:
–
pH is a way of describing the acidity or the alkalinity of a substance, its a measure of the concentration of
hydrogen ions per litre of solution, so the more acidic a substance is, the more hydrogen ions, the LOWER the pH.
–
The pH scale is from 0 to 14: a pH of 7 is neutral (pure water); above 7 is alkaline and below 7 is acidic.
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
Identify data sources, plan, choose equipment or resources and perform a
first-hand investigation to test the effect of increased temperature, change
in pH and change in substrate concentrations on the activity of enzymes:
–
Aim: To test the variety of factors (such as temperature, pH (acidity/alkalinity), substrate concentrations) on the
effect on enzyme activity.
–
Equipment:

Potato pieces/living tissue (ie cow liver pieces) (both contain the enzyme catalyse)
 Catalyse is a enzyme that breaks poisonous hydrogen peroxide into harmless water and oxygen gas

20 test-tubes

Hydrogen peroxide (H2O2)

Acid: H2SO4, Base: NaOH

Source of heat (ie hot plate)

pH probe

Thermometer
–
Safety:

Hydrogen peroxide is an extremely poisonous substance, it must not be ingested, and teacher supervision is
needed.

Hot plate can reach temperatures well over 200-400 degrees, it must be put in a rigid and safe position.

Gloves and glasses must be worn, in case of accidental test-tube damage.
–
Method:

3 separate tests were carried out in test tubes with potatoes placed in them; pH, temperature, substrate
concentration.

Evidence for enzyme activity came from the sound of 'fizzing effect', the louder the more activity is presumed.

This is further determined by the 'formation of bubbles', where bubbles that are in greater in height show greater
activity.
–
Result:
–
pH:

Each enzymes work best at its optimum pH, which is usually within a very narrow range, for example enzymes
in the stomach can work at 1-2 pH , whilst enzymes as catalase work at 7 pH.

Extremes of acidity or alkalinity can affect the bonds holding the 3D globular shape of the enzyme. Thus losing
activity and distorted.
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–
Temperature:

As temperature increases, MOST enzyme activity increases, up to the optimum temperature (a particular
temperature, approx. 40°C, an enzyme is most active). This is because the enzyme and substrate molecules
move faster as (more kinetic energy) and therefore more collisions between enzyme and substrate occur.

At very high temperatures, the activity of the enzyme falls rapidly, because the heat energy breaks the bonds
that cause the protein to fold, so destroying the active site in a irreversible process, called denaturation.
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–
Substrate concentration:

An increase in substrate concentration will increase the reaction until all enzyme active sites are occupied this is
known as saturation point, thus reaction proceeds at maximum rate (VMax or Maximum velocity). A further
increase in substrate, cannot increase the rate because the are no active sites available.

Explain why the maintenance of a constant internal environment is important
for optimal metabolic efficiency:
–
Metabolism is severally affected by enzymes, and hence the functioning of an organism. Enzymes work best
within a limited range of environmental conditions, but their efficiency is affected greatly by certain factors which
include temperature, pH and substrate concentration.
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–
Hence a constant and stable internal environment is needed so that enzymes will always be working at an optimum
rate, and thus metabolism will be a optimum efficiency, if these factors do not remain relatively stable then the
rate of enzyme-catalysed reactions decrease, this rate could affect an entire metabolic pathway.

Describe homeostasis as the process by which organisms maintain a relatively
stable internal environment:
–
Homeostasis is the process by which organisms maintain a relatively stable (constant) or almost constant, internal
environment.
–
Homeostasis falls into 2 categories, depending if it is exothermic (doesn't produce own heat) or endothermic
(produce own heat). An organism may be a conformer or a regulator.

Regulators try to maintain the parameter at a constant level over possibly wide environmental variations.

Conformers allow the environment to determine the parameter.

Explain that homeostasis consists of two stages
–
–
Detecting changes from the stable state;
–
Counteracting changes from the stable state:
Homeostasis in endotherms is carried out in 2 steps, this mechanism is known as feedback:

Detecting change.

Counteracting the change.
–
Detecting Changes:

Any change that provokes a response is a stimulus.

Receptors detect stimuli.
 Examples of external stimuli: light, day length, sound, temperature, odours.
 Examples of internal stimuli: levels of CO2, oxygen levels, water, wastes.

–
Receptors can range from a patch of sensitive cells, to complex organs like the eyes and ears of mammals.
Counteracting Changes:

After receptors detect changes, organisms can then react to the change.

This type of response will counteract the change to ensure the stable state is maintained.

Effectors bring about responses to stimuli.

Effectors can either be muscles or glands:
 Muscles bring about change by movement
 Glands bring about change by secreting chemical substances

Gather,
process
and
analyse
information
from
secondary
sources
and
use
available evidence to develop a model of a feedback mechanism:
–
The mechanism that brings about homeostatic change is called FEEDBACK
–
Homeostasis does not maintain the exact set point, but homeostasis is maintained as long as there is only a narrow
range of fluctuation (increase and decrease) of the variable around the set point. If the fluctuation is large (this is
the most common in humans), and exceeds the normal range, a negative feedback mechanism comes into
operation in response to this change; it is termed negative because it counteracts (negates) the change, thus
returning the body to within the normal range.
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–
In living organisms, the feedback system has 3 main parts:

Receptors: a type of sensor that constantly monitors the internal environment

Control Centre: receives info from the receptors and determines the response

Effector: Restores the set value. Keeps environments stable.
–
An example of a feedback system would be the control of carbon dioxide levels (an increase in it):

Outline
the
role
of the
nervous system
in
detecting
and responding
to
environmental changes:
–
The nervous system is an organ system containing a network of specialized cells called neurons that coordinate
the actions of an animal and transmit signals between different parts of its body.
–
The nervous system works to regulate and maintain an animal’s internal environment and respond to the external
environment, ie maintain homeostasis.
–
The nervous system is made up of two parts:
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
Central Nervous System: This acts as a CONTROL CENTRE for all the body’s responses and it coordinates
all these responses, it consists of the brain (specifically hypothalamus) and the spinal chord where it receives
information, interprets it and initiates a response.

Peripheral Nervous System: This is a branching system of nerves that connects receptors and effectors. This
system transmits messages from the central nervous system and back. It acts as a communication channel.

Identify the broad range over which life is found compared with the narrow
limits for individual species:
–
Ambient temperature literally means the temperature of the environment; room temperature implies a
temperature inside a temperature-controlled building (the building has specific parts which affect the ambient
temp).
–
Organisms on Earth life in environments with ambient temperatures ranging from less than 0ºC (such as arctic
animals) to more than 100ºC (such bacteria found in boiling undersea volcano vents).
–
However, individual organisms cannot survive this entire range of temperatures for example mammals can only
survive temperatures from about 0 - 45ºC.
–
This means that life is found in a very wide range of temperatures, but individual species can only be found in a
narrow temperature range.

Compare responses of named Australian ectothermic and endothermic organisms
to changes in the ambient temperature and explain how these responses assist
in temperature regulation:

Analyse
information
from
secondary
sources
to
describe
adaptations
and
responses that have occurred in Australian organisms to assist temperature
regulation:
–
Ectotherms (cold blooded): are organisms that have a limited ability to control their body temperature (due to
their cellular activities generate little heat). Their body temperatures rise and fall with ambient temperature
changes.

–
Most organisms are ectotherms; examples are plants, all invertebrates, fish, amphibians and reptiles.
Endotherms (warm blooded): are organisms whose metabolism generates enough heat to maintain an internal
temperature independent of the ambient temperature.

–
Examples are birds and mammals.
Ectothermic response; Central netted dragon (Ctenophorus nuchalis):

Increase in temperature (ie hotter):
 Stays in sheltered areas to avoid extreme heat. They can dig burrows or seek shelter in caves or crevices. This
reduces the effect of heat on their body.
 It can change into nocturnal animal when the temperature becomes very hot. Many desert animals sleep in
burrows during the day and are active at night, to escape the heat.

Decrease in temperature (ie colder):
 It will change its body position, to expose more of its body surface area to sun's rays, increasing core body
temperature.
 They will seek areas of higher heat rays, such as on top of ledges instead of burrows.
–
Endothermic response; Red Kangaroo (Macropus rufus):
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
Increase in temperature (ie hotter):
 It licks its arms to cool itself. The evaporation of the saliva cools its skin by convection.
 It becomes less active, activity generates heat as many reactions are exothermic (release heat).

Decrease in temperature (ie colder):
 Insulation: they have a thick fur layer, and contract their muscles controlling and shiver to generate heat.
 They seek group warming, where they are exposed to less cold air.

Identify some responses of plants to temperature change:
–
Since plants cannot move from environment to environment, they respond to temperature by various changes:
–
Increase in temperature (ie hotter):

Leaf orientation: Some plants can change the orientation of their leaves in relation to the sun at different times,
for example their leaves hang down vertically, to reduce exposure, thus controlling temperature.

Growth rates: They alter their growth rate for example; some Eucalyptus trees grow more in spring than in
winter, hence using less water which can be use for cooling itself.
–
Decrease in temperature (ie colder):

Deciduous trees (trees that shed their leaves for a part of every year) lose their leaves in winter (leaf fall) and
undergo a period of dormancy, which allows them to survive not only the extremely low temperatures, but also
water shortages and lower availability of sunlight.

Plants may die above the ground, but leave bulbs, roots, rhizomes or tubers to survive underground. These then
sprout when favourable conditions return.
2.
Plants
and
animals transport
dissolved
nutrients
and
gases in
a fluid
medium:

Perform a first-hand investigation using the light microscope and prepared
slides to gather information to estimate the size of red and white blood
cells and draw scaled diagrams of each:
–
Aim: To estimate the size of red blood cells and white blood cells seen with a light microscope.
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–
Equipment:

Light microscope

Prepared slides of human blood

1mm sized Mini-grid plastic paper

Pencil and drawing paper
–
Safety:

Slides can have sharp or unseen flint pieces of glass, gloves and glasses should be worn.

Use commercially prepared microscope slides of blood and not fresh blood, to eliminate the risk of contracting
blood-borne disease.
–
Method:

The microscope on normal view ie 1X, has a limited field of view of 16mm.

Hence set your microscope with the millimetre-squared graph paper first. Then 'click' the 1X objective lense,
this will show you what the 'normal' eye of 16mm can see.

Then click the 10X objective, this will magnify the 10mm by a factor of 10. Hence now youll see a maximum
field of view of 1.6mm, and its sub-ten components. (also note 1mm= 1000µm)

Now using the 40X objective, this now makes the initial 16mm diameter four times less then the 10X, so the
diameter is approximately 0.4mm. Hence this diameter is 0.4mm, or 400µm

Now, putting a slide of a prepared blood, at 40X objective, estimate how many blood cells there exists in that
'field of view', approximately 50 red blood cells exist, hence the size of 1 RBC is 400 µm divided by 50
(400/50), which is 8 µm.

Now for white blood cells since there are so few of them, it is NOT possible to count the number of white cells
across the diameter, and even much more difficult to estimate how many would fit across the diameter. Hence
there size is estimated by proportion in comparison to that of RBC.
– Result:
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
Red blood cells (Erythrocytes):
 Size: 6-9 µm
 Shape: Bi-concave (concave on both side) discs
 Function: Transport of oxygen.
 They have no nuclei; they only live for 3 months. After this they are destroyed in the liver
or spleen.
 5-6 million in every millilitre of blood.
 They are produced in the bone marrow

White blood cells (Leucocytes):
 Size: 12-15 µm
 Shape: Irregular shape; can change shape
 Function: To defend against disease
 Only 4-12 thousand per millilitre of blood
 They have nuclei, unlike red blood cells
 They are produced in the lymph glands.

Identify the forms in which each of the following is carried in mammalian
blood:
–
–
Carbon Dioxide
–
Oxygen
–
Water
–
Salts
–
Lipids
–
Nitrogenous wastes
–
Other products of digestion
Carbon dioxide:

It is produced as a waste product of respiration in body cells. As its concentration is higher in the cell than in the
blood its diffuses in the blood:
 70% of the carbon dioxide is converted into carbonic acid then changed into hydrogen carbonate ions. This
change from carbon dioxide to carbonate ions happens on the red blood cells. The ions are transported in the
plasma, NOT dissolved in it.
Carbon + Water
Dioxide
CO2
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+
H2O
Carbonic
Acid
Hydrogen +
Ions
H2CO3
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Hydrogen
Carbonate Ions
H+ + HCO-
Page 12 of 37
 Bind to haemoglobin in erythrocytes forming carbaminohaemoglobin (only 23% of the carbon dioxide).
 Be dissolved directly in the plasma (only 7% of the carbon dioxide).
–
Oxygen:

Oxygen is needed in the body for respiration. It is brought in across the respiratory surfaces of the lungs.

It binds with haemoglobin in red blood cells, forming oxyhaemoglobin.
–
Water:

Water is the solvent of plasma; it makes up the bulk of blood volume.

It makes up 60% of the volume of blood.
–
Salts:

These are transported directly dissolved in the plasma as ions (ie NaCl as Na+ and Cl-), these are known as
electrolytes.
–
Lipids and other products of digestion:

The aim of digestion is to break large molecules down to a size small enough for absorption through the
intestine wall and into the bloodstream, so that they can be transported to cells in the body where they are
required.

Lipids are any of a group of organic compounds (ie containing carbon), including the fats, oils, waxes, sterols,
and triglycerides that are insoluble in water, are oily to the touch, and together with carbohydrates and proteins
constitute the principal structural material of living cells.
 Digested lipids are changed into triglycerides (this happens in the lining of the small intestine).
 Lipids are then transported as chylomicrons (these are clusters of triglycerides, phospholipids and
cholesterol), wrapped in a coat of protein.
 These are released into the lymph and eventually pass into the veins
–
Other products:

Nitrogenous wastes:
 Wastes such as ammonia are changed in urea
 Urea is transported dissolved in the plasma

Minute minerals:
 Includes amino acids, sugars and vitamins
 They are mainly water soluble and transported in the plasma.
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
Explain the adaptive advantage of haemoglobin:
–
Haemoglobin is a protein made up of four polypeptide chains (called globins) and each is bonded to a haem
(iron-containing) group which can attach to an O molecule, forming oxyhaemoglobin.
–
For every haemoglobin, 4 oxygen molecules can attach. There about 250 million molecules of haemoglobin in
each red blood cell, hence the very high oxygen carrying capacity.
–
If blood carried oxygen without haemoglobin, the oxygen would have to be dissolved directly into the plasma
(into water). But oxygen is not very soluble in water therefore, if oxygen was carried only by being dissolved in
blood plasma, 100 ml of water would only be able to carry 0.2 ml of oxygen.
–
The presence of haemoglobin increases the oxygen carrying capacity of blood by 100 times

Dissolved only

Haemoglobin
–
0.2 ml O2/ 100 ml blood
20 ml O2/ 100 ml blood
The adaptive advantage:

It increases the oxygen carrying capacity of blood (proven above). Mammalian cells need a lot of energy and
therefore must have a continual supply of OXYGEN for RESPIRATION; this ability of blood to carry large
quantities of oxygen gives mammals a considerable survival advantage. The extra energy allows mammals to be
active, as well as grow large.

It has the ability to bind oxygen at an increasing rate once the first oxygen molecule binds to it. The bonding of
each oxygen molecule causes the haemoglobin to change slightly in shape, making it easier for every subsequent
oxygen molecule to bind to it. This increases the rate and efficiency of oxygen uptake. As a result, a very small
increase in the oxygen concentration in the lungs can result in a large increase in the oxygen saturation in the
blood.

It has the capacity to release oxygen at an increasing rate when carbon dioxide is present. Metabolising cells
release carbon dioxide, which combines to form acidic carbonic acid, and this lower pH, thus increases chances
to affect enzymes, and toxicoses cells (acid is corrosive).

It can undergo the Bohr effect, which at lower pH (due to increasing CO2) levels can release oxygen to tissue
areas that in need of it.

Outline the need for oxygen in living cells and explain why the removal of
carbon dioxide from cells is essential:
–
Cells require oxygen in the process of respiration:

–
Glucose + oxygen
carbon dioxide + water + energy (in the form of ATP).
Carbon dioxide is a waste product and must be removed to maintain the normal pH balance of the blood. By
removing excess carbon dioxide, it prevents a build up of carbonic acid, which causes the lowering of the pH, and
therefore increasing breathing rate and depth. Carbonic acid forms when carbon dioxide dissolves in water. At
normal levels, the carbon dioxide; bicarbonate ion (HCO3-) equilibrium is an important mechanism for buffering
the blood to maintain a constant pH, if greater amounts of carbon dioxide are produced the body cells (blood and
lymph) will become acidic, enzymes can only function within a specific pH range, therefore an increase in carbon
dioxide will result in lowering the pH which will affect the overall metabolism of the body.

Perform a first-hand investigation to demonstrate the effect of dissolved
carbon dioxide on the pH of water:
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–
Aim: To model the effect of carbon dioxide on the pH of water.
–
Equipment:

25ml of Distilled water in 100mL beaker

Universal indictor (its an indicator that changes colour depending on the pH of a solution)

pH probe attached to data logger
–
Safety:

Gloves and glasses should be worn, in case of glass breaking.

The water can become corrosive due to increasing pH, it should NOT be ingested after use, dispose in an
organic waste container.

–
Straws should NOT be used by more then one student, to minimise contracting diseases.
Method:

In a beaker, pour water till the 25mL grade mark, then put 3 drops of universal indicator, this should now
change into greenish colour.

Then put the pH probe, and check the pH is about 7.

Exhale air into the straw that is dipped into the solution, for about 3 minutes.
–
Result:

After about 30 seconds, the colour of the solution began to change into pale yellow, and the pH on the data
logger started decreasing.

This is because carbon dioxide forms a weak acid; carbonic acid (H2CO3) so the water becomes more acidic.
Carbonic acid in water dissociates to form hydrogen carbonate ions (HCO3-), and some carbonate ions (CO32-).
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
Analyse information from secondary sources to identify current technologies
that
allow
measurement
of
oxygen
saturation
and
carbon
dioxide
concentrations in blood and describe and explain the conditions under which
these technologies are used:
Technology
Pulse
oximeter
How it Works
The Conditions It Is Used
Measures O2 levels ONLY.
Used in many conditions; this is because it is
Device like a peg sits on the finger and
painless, easy to apply and quick to give results,
measures the transmission of light through
example:
tissues ie measures the amount of oxygen in

arterial blood.
anaesthesia.
There is a large difference between red light

absorbed by haemoglobin compared to
oxyhaemoglobin, hence this can be analysed
gas (ABG)

Measures
pressure

(or
the
concentration) of O2 and CO2 in the
analysis

Used when there are signs of dangerously low
oxygen or high carbon dioxide levels.

Helpful
for
monitoring
patients
anaesthesia, in intensive care, in accident or
Measures saturation of oxygen (which is
emergency facilities and for premature babies.
haemoglobin
compared
to
the
maximum)

Helps for diagnosing as well as monitoring
patients eg a patient in a coma can have their
blood gases regularly monitored.
Measures levels of bicarbonate and pH
(to show CO2 levels)
This analysis evaluates how effectively the
lungs are delivering oxygen and removing
carbon dioxide.
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under
blood
the amount of oxygen combined to

Can be used as a general check-up procedure to
analyse O2 levels
Measures O2 and CO2 levels.

Monitor premature babies that are in neo-natal
wards.
to give a reading.
Arterial blood
During surgeries, to monitor patients under
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
Compare the structure of arteries, capillaries and veins in relation to
their function:
Arteries
Veins
Structure
Thick walled, elastic, muscular
Thinner walls then arteries, elastic, less
muscle , wider diameter (larger lumen)
Direction of blood:
flow / pressure
Carry blood away from heart, pressure
created by hearts pumping puts stress on
arteries, blood pressure is high
Contain muscle fibres which contract and
relax, rate is maintained as blood travels in
spurts towards body tissues
Oxygenated blood taken away from heart
Carry blood to heart, as there is no stress on
veins the blood pressure is low
Diagram
Blood movement and
rate
Carries
–
Contain no muscle, rely on valves and when
large muscle contract they help push the blood
flow through the veins
Deoxygenated blood taken to the heart
Capillaries:

Capillaries are an extension of the inner layers of the arteries and veins (Artery  arterioles  capillary 
venules  veins).

Capillaries are only one cell thick, and are so narrow, that only one red blood cell can pass at a time.

Capillaries surround all tissue cells, thus they provide a very large surface area over which exchange of
materials between blood and body cells can occur.
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
Describe the main changes in the composition of the blood as it moves around
the body and identify tissues in which these changes occur:
–
Pulmonary circuit (From Body to HEART to the Lungs):

Blood enters the right atrium of the heart via the vena cava (major vein):

The blood is deoxygenated, and high in carbon dioxide.
 It is also low in glucose and other nutrients; high in urea, other nitrogenous wastes and various poisons.

As the heart beats, the right ventricle pumps the blood through the pulmonary artery, to the lungs:

Here the blood gains oxygen through exchange with alveoli in the lungs (ie air sacs), and loses its carbon
dioxide.

–
The blood then enters the left atrium via the pulmonary vein.
Systemic circuit (From Lungs to HEART to the Body):

The left ventricle pumps oxygenated blood to the body through the aorta.

In the body, various changes occur to the blood.

The blood loses oxygen and gains carbon dioxide in all body cells, as respiration occurs.

In the Liver:
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 Levels of glucose are regulated: excess glucose is changed to glycogen, or glycogen stores are changed to
glucose (if needed).
 Excess amino acids are changed to ammonia, and then to urea.
 Poisons are also reduced, as the liver changes them to less toxic forms.

In the Intestines:
 Levels of nutrients from digestion increase.
 Glucose, amino acids, ions, lipids and other substances from food enter the blood.

In the Kidneys:
 Salt and water levels are regulated.
 All urea is removed, toxins are excreted into the urine.


The changed blood, again highly deoxygenated, from the body then flows back to the pulmonary circuit.
Analyse information from secondary sources to identify the products extracted
from donated blood and discuss the uses of these products:
–
Red blood cells:

Used to increase the amount of oxygen that can be carried to the body’s tissues; given to anaemic patients, or
people whose bone marrow do not make enough red blood cells
–
Plasma:

This liquid portion of the blood, is given to people with clotting disorders (such as haemophilia), and also used
to adjust the osmotic pressure of the blood (to pull fluids out of tissues).
–
White blood cells:


Infection fighting component of the blood.
Analyse and present information from secondary sources to report progress in
the production of artificial blood and use available evidence to propose
reasons why such research is needed:
– The problems of using real blood:

Shortage of real blood

It has to be ‘cross-matched’. This is because, if you receive the wrong type of blood, it can be fatal. This is a
great disadvantage in emergency situations.

It has to be free of infectious agents. Only blood that is free of bacteria and infectious agents (such as HIV) can
be used. Testing the blood is costly.

It has a short shelf-life. Because red blood cells only survive for 3 months, the blood has a short life span (blood
can only survive for 3-4 weeks).
– Proposed replacement; Perflurochemicals (perflurocarbons):

Synthetic and inert, are completely sterile

Cheap to produce, compared to using real blood.

Can dissolve 5 times more oxygen than blood.

Free of biological materials, therefore no risk of infections

BUT; must be combined with other materials to mix in with the bloodstream (eg lecithin).
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
Choose
equipment
gather
first-hand
or
resources
data
to
to
draw
perform
transverse
a
first-hand
and
investigation
longitudinal
sections
to
of
phloem and xylem tissue:
–
Aim: To draw the transverse (top view) and longitudinal section (side view) of plant tissue (ie xylem and phloem).
–
Equipment:

A stick of celery

Red food colouring

Water in a 100mL beaker

Razor blade

Light microscope
–
Safety:

The razor blade is extremely sharp, gloves should be worn incase of accidental flicking of blade onto skin.

Glasses should be worn incase of glass breaking.
–
Method:

In the 100mL beaker filled with water, put 3-5 drops of red food colouring into the solution. It should change to
dilute red colour.

Place the celery stick into the beaker, and leave it over night, so the coloured water can seep into the plant
sections to rise through xylem vessels, hence staining them strongly. Some water also travelled down the
phloem vessels.

Using a sharp one-sided razor blade, very thin slices were cut from across the stalk (for the transverse section)
and from the length of the stalk (for the longitudinal section).

Suitable slices were then prepared as wet mounts and viewed under a light microscope.
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–
Result:
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
Phloem:

Xylem:

Describe current theories about processes responsible for the movement of
materials through plants in xylem and phloem tissue:
–
There are 2 types of transport tissues in plants:

Xylem: This transports water and mineral ions upwards from the roots to the leaves of a plant.
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
–
Phloem: This transports organic materials (particularly sugars) up and down the stem to other parts of the plant.
There exist two theories (ie possible explanations based on evidence) into how water/nutrient moves in each tissue
respectively.

In Xylem:
 The transpiration stream theory (ie cohesion-adhesion-tension theory) possists that due to physical forces of
water (and ions) being removed from the plant stomates by passive transport (ie transpiration), causes a
column of water to be sucked up into the stem by the evaporative pull, also the low concentration of water at
the roots allows more water to diffuse in.
 Once water has been absorbed into the roots of plants (by osmosis) along with mineral ions (by diffusion and
active transport), these substances move across the root into the xylem. A small amount of root pressure
results from the continual influx of more water and ions, hence forcing the solution already present upwards
(due to pressure build up), however this is usually not enough.
 The constant loss of water, leads to a transpiration stream (which is the constant upward flow of water
through a plant), this is because of waters 2 properties, which are adhesive forces (the ability of molecules to
attach to walls), and cohesive forces (the attraction of molecules to each other), hence leading to the
capillarity (water rising up through bore of tissue) and hence the stream.

In Phloem:
 The pressure flow theory (ie source-path-sink theory) states that in the plants, there are sources of nutrients,
e.g. leaf cells are the sources of sucrose. As the sucrose, amino acids and other minerals build up, the cells
actively transport the glucose sugars by active transport into the phloem tubes, this is known as loading, it
can be done by 2 ways:

Symplastic Loading: Sugars and nutrients move in the phloem from the mesophyll cells to the sieve
elements through the plasmodesmata that join adjacent cells (note: Plasmodesmata have not been found in
all plants).
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
Apoplastic Loading: sugar and nutrients move along the cell walls to the sieve plate. Then they cross the
cell membrane by active transport to enter the phloem tube.
 As sugars enter the phloem the concentration of phloem sap increases, this causes the entry of water by
osmosis from the surrounding cells (osmotic pressure gradient is low). This resulting pressure causes water
and dissolved solutes to flow towards a SINK.
 A sink is a region of the plant where sugars and other nutrients are actively begin removed from the phloem.
As sugars move out of the phloem, water flows out with them. This reduces the pressure in the sieve cells at
the sink region.
 Materials are transported both up and down the stem and are distributed especially to the growing points and
reproductive structures, including developing fruits and seeds, it is driven by a gradient generated osmotically.
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3. Plants and animals regulate the concentration of gases, water and waste
products of metabolism in cells and in interstitial fluid:

Explain why the concentration of water in cells should be maintained within
a narrow range for optimal function:
–
Water makes up around 70-90% of living things; it is essential for life, it is the solvent of all metabolic reactions in
living cells (universal solvent), and sometimes directly takes part in it (eg. respiration). Therefore a deviation can
cause:

Isotonic: Concentration of solutes outside the cell is the same as inside the cell. No overall movement of water.

Hypertonic: Concentration of solutes is greater outside the cell than inside. Water tends to move out of the cell.

Hypotonic: Concentration of solutes is greater inside the cell than out. Water tends to move inside the cell.
–
Living cells work best in an isotonic environment where the levels of water in cells need to be kept relatively
constant, any change in the concentration of solutes will result in a change in the levels of water in cells which
usually results in death (either dehydration or cell bursting)
–
Enzymes also require specific conditions of functioning, some of which could relate to the levels of water and
solutes in cells, as an increase in water changes the concentration of acid (either dilutes it or makes it
concentrated).

Explain why the removal of wastes is essential for continued metabolic
activity:
–
As a result of metabolism, many waste products are formed, for example:

In the process of deamination (process by which amino acids and proteins are broken down into ammonia),
ammonia is highly toxic and must be removed or changed to a less toxic form. It can greatly increase the pH and
make it more alkaline.

–
It carbon dioxide acculmates, it can form carbonic acid, which lowers the pH.
If these toxins are allowed to accumulate, they would slow down metabolism and kill the cells (e.g. excess toxins
is acidic thus increases pH, affection enzyme function which can lead to denaturation), this is why they need to
quickly be removed, or converted into a less toxic form.
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
Identify the role of the kidney in the excretory system of fish and mammals:
–
The maintenance of a constant concentration of nutrients, water and waste products in the internal environment of
organism, is crucial to its wellbeing. The concentration of these substances directly affects metabolism in cells,
and hence needs to be balanced.
–
Many wastes are excreted (process by which waste products, which have been produced as a result of metabolism,
are removed from the body). The excretory system is made up of systems and organs that carry out the removal of
metabolic wastes.

Carbon dioxide is excreted via the lungs (ie respiratory system).

Nitrogenous wastes are removed along with excess salts and water via the kidneys (ie urinary system).
–
The kidney is an organ of the excretory system of both fish and mammals. It plays a central role in homeostasis,
forming excreting urine while maintaining osmoregulatory.
–
Osmoregulation: means the physiological processes that an organism uses to maintain water balance; that is, to
compensate for water loss, avoid excess water gain, and maintain the proper osmotic concentration (osmolarity) of
the body fluids.

Distinguish
between
active
and
passive
transport
and
relate
these
to
processes occurring in the mammalian kidney:

Explain how the processes of filtration and reabsorption in the mammalian
nephron regulate body fluid composition:
–
Active transport: is the process of using energy to transport substances across highly concentrated membrane
from an area of low concentration, it would normally not be able to cross due to a concentration gradient (the
amount of substance in a particular area).
–
Passive transport: is the process of movement substances across a membrane from an area of higher
concentration to an area of lower concentration without energy expenditure (this is diffusion and osmosis).
–
The excretory system is a group of organs that function together remove metabolic wastes from the tissues of an
organism and expel them to the outside, a kidney is the main excretory organ responsible for removing
nitrogenous wastes from the bodies of vertebrate animals (including fish and humans).
–
The function of the kidney in excretion is to filter the blood that enters it, removing the waste in the blood
solution, for this waste to be excreted. This filtration is carried out by millions of small filtering units that are in
kidneys which are known as nephrons.

The nephron is a regulatory unit; it absorbs or secretes substances in order to maintain homeostasis, this
regulation maintains the constant composition of body fluids which is done by adjusting salts and water levels to
maintain fluid concentration, different ions also adjusted to maintain pH.
–
Urine is the final solution produced by these microscopic tubules, and passes out the kidney via ducts (ureters) and
then goes to the urine storage organ (bladder), which after a certain limit fills and the human passes this urine
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Page 26 of 37
through the urethra to the outside. (In vertebrates this goes to the a chamber (cloaca) instead of the urethra, which
empties to the outside)
–
Detailed structure of a nephron:

It consists of 4 parts (in order of movement) THAT are heavily surrounded by capillaries: Bowmans capsule
Proximal (ie first) convoluted tubule
the loop of Henle
Distal (ie second) convoluted tubule
collecting duct which produces urine that leads to the bladder.
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–
Function of nephrons

Three main process occur in the kidney, in the parts mentioned above, they are filteration
reabsorption
secretion.

Filtration:
 When highly oxygenated, unfiltered blood enters the kidney through the renal artery it goes to the nephrons,
upon reaching it splits into a spherical network of blood capillaries called glomerulus that are in a Bowman's
capsule, the blood pressure here is so high that fluid and substance from the blood are forced into the
Bowman’s capsule, and forms a fluid called the glomerular filtrate.
 Blood cells and proteins are retained in the blood, while large volumes of water pass through contained
dissolved substances such as: water, amino acids, glucose, salts (ions), nitrogenous wastes and other toxic
molecules.
 This process is known as filtration, it separates based on SIZE of molecules, since proteins and RBC are
larger then other molecules they cannot pass the Bowmans capsule. Therefore:

Substances that the body needs will require reabsorption, so they are not lost with urine.

Additional wastes that were in the bloodstream, and managed to escape the higher pressure of the Bowmans
capsule need to be added to this 'urine' mixture.
 Hence this is not the final fluid excretion.
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
Reabsorption:
 Depending on the feedback of the body, varying amounts of solutes are reabsorbed from the solution, for
example water, amino acids, glucose, salts (Na+, K+, Cl-, Ca2+, Mg2+, HCO3-).
 This occurs in the proximal, loop of Henle and distal tubules.
 In the proximal tube:

All organic nutrients (amino acids and glucose) are reabsorbed, aswell as some ions such as (Na+, K+, Cl-,
Ca2+, Mg2+, HCO3-).
 In the loop of Henle:

After the initial reabsorption from the distil tube, you'll have a liquid that is primarily urine, whether its
concentrated or not, is dependent in the loop of Henle.

The loop of Henle has 2 limbs, a descending then ascending, where the descending is permeable to water
ONLY, and the descending is permeable to salt ONLY.

Secretion:
 This is the last process and leads to the formation of urine. It occurs in the distil and collecting tubule.
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 The liquid present in the tubule, are then added with metabolic wastes (such as urea, ammonia, hydrogen ions,
durgs: pencillin, morphine) etc that are brought by active transport to the distil tubule.

Explain
why
the
processes
of
diffusion
and
osmosis
are
inadequate
in
removing dissolved nitrogenous wastes in some organisms:
–
Diffusion and osmosis are both examples of passive transport (ie they do not require energy), this is too slow for
the normal functioning, because the movement of molecules relies on differences in the concentration gradient
between two solutions (it moves from high conc. to low conc.)
–
Also this process greatly slows down once the difference in concentration gradient becomes smaller, and stops
once the concentrations are at equilibrium.
–
Further problems with:

Diffusion:
 Toxins such as drugs can accumulate in the body, and can only be removed if they are in water, hence they
would ONLY move if there was a higher concentration of toxins in the blood then the urine itself. And this
would stop if the concentrations equalise.

Osmosis:
 Too much water is lost in urine: If there is a high concentration of urine, water will continually be drawn from
the body to even out the conc. gradient. However, excretion of dilute urine means the loss of large amount of
water from body, a loss to great for terrestrial animals.
 Osmosis only deals with the movement of water and thus would only allow water to move out of the body,
not the nitrogenous wastes.

Perform a first-hand investigation of the structure of a mammalian kidney by
dissection, use a model or visual resource and identify the regions of the
mammalian kidney involved in the excretion of waste products:
–
Aim: To identify the regions of the mammalian kidney, notably the ones involved in the excretion of waste
products.
–
Equipment:

One commercially packed cow (mammalian) kidney

One sharp medical cutting scalpel

Dissecting tray

Clean 'laying' paper

Latex gloves

Tissue forceps (they are things that help pull skin)

Disinfecting agent
–
Safety:

Gloves and protective face masks are crucial, incase of a diseased kidney, or the possible contracting of a
disease between touching.

Gloves are also crucial in handling of sharp object, incase of accidental damage.
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
Disinfecting agent was used on the tray, and the paper, incase of airborne particles that may be ingested and
cause allergies or disease.

–
Material was carefully disposed, to inhibit the build up of bacteria and other organisms.
Method:

Carefully layer brush the tray with agent, and paper, and place them together.

Place the kidney facing sideways, and carefully cut sideways to obtain a 'longitudinal' cut (ie sideway cut), using
forceps to open the skin.
–
Result:

The kidney is made up of 3 sections, the pelvis, the medulla and the cortex, the obvious observable sections
where located, and an imaginary "large" nephron was placed, to observe where the 3 mains process (ie
filteration
reabsorption
secretion) occur.
 Cortex:

Contains the glomeruli. It is very dark red due to the capillaries

It is involved in the filtration of blood.
 Medulla:


Contains the nephron tubules, as can be observed by the striped appearance of the medulla

It is involved in the reabsorption and secretion of substances
Pelvis:


It is where all the collecting ducts connect to, ie the collecting of urine.
Gather, process and analyse information from secondary sources to compare
the process of renal dialysis with the function of the kidney:
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–
People with disfunctional kidneys are not able to remove wastes such as urea, they have to undergo renal dialysis
to regulate their blood.
–
Renal dialysis is an artificial process in which waste in the blood are removed by diffusion across a partially
permeable membrane of solution known as dialysis fluid. It is a solution of salts, glucose, dissolved gases and
other substances (it has an equivalent composition to interstitial fluid), wastes (particular urea and excess salts),
diffuse out of the blood into the dialysis fluid. The clean blood is then returned.
–
The process:

The blood is extracted from the body from a artery (as it has come from the heart with oxygen, and going to
body to pass its waste and regulate levels etc, but it cant as kidney has failed hence blood from artery is used)
and passed into a dialyser, which is is a medical unit which is a bundle of hollow fibres made of partially
permeable membrane to help units suffering from artery failure.

The dialyser is in a solution of dialysing fluid, which has similar concentrations of substances as blood.

The dialyser only allows wastes to pass through, and not blood cells and proteins (in this way it is similar to the
filtrations stage of the nephron).

The wastes diffuse into the solution, and it is constantly replaced

The anti-clotting agent, heparin, is also added to prevent clotting.

The blood is then returned to the body via a vein.
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–
Comparison of dialysis and normal kidney function:
Kidneys
-
Renal Dialysis
Continuous process; very efficient
-
Slow process; occurs a few times a week for
patients
-
Active and passive transport is used throughout
-
Only passive transport is used
-
Useful substances are not reabsorbed as they
the nephron
-
Useful substances are reabsorbed actively by
the kidney
-
diffuse into blood from dialysing fluid
Uses a series of membranes (nephrons) which
-
are selectively permeable.

Outline
the
role
of
Also uses membranes (but artificial) which are
selectively permeable.
the
hormones,
aldosterone
and
ADH
(anti-diuretic
hormone) in the regulation of water and salt levels in blood:
–
Recall:

Dehydration is defined as an excessive loss of body fluid.

Blood volume is the volume of blood (both red blood cells and plasma) in a person's circulatory system. Blood
volume is determined by the amount of water and sodium ingested, excreted by the kidneys into the urine.
–
A hormone is a chemical released by one or more cells that affects cells in other parts of the organism. It is
essentially a chemical messenger that transports a signal from one cell to another, only a small amount of hormone
is required to alter cell metabolism. All multicellular organisms produce hormones however animals usually
produce hormones which are often transported in the blood.
–
The kidneys maintain constant conditions within the body by excreting wastes such as urea and by regulating the
amounts of water and salts that are reabsorbed. This aspect of homeostasis is mainly due to the actions of two
hormones: aldosterone and antidiuretic hormone (ADH):
–
ADH (Anti-Diuretic Hormone):

Also called vasopressin, anti-diuretic hormone literally means (anti-'water losing'), diuretic are heavily used in
pro-bodybuilding shows to lose water.

It controls the reabsorption of water, this is done by adjusting the permeability of the collecting ducts and the
distal tubules.
 Hence a release of it (ie increase levels), increases (sucks) water out from the tubules, hence the urine
becomes more concentrated (as less water is present).

It is made in the hypothalamus in the brain, but stored in the pituitary gland.

Receptors in the hypothalamus monitor the concentration of the blood:
 High Salt Concentration: ADH levels increased, collecting ducts and distal tubules become more permeable to
water, more water reabsorbed, concentration returns to normal. (Concentrated urine)
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 Low Salt Concentration: ADH levels reduced, collecting ducts and distal tubules less permeable to water, less
water absorbed, concentration returns to stable state. (Dilute urine)

ADH does not control the levels of salt in the blood. It only controls the concentration of salt through water
retention.
–
Aldosterone:

Is a hormone that increases the reabsorption of sodium and the release (secretion) of potassium in the kidneys.
Hence a release of it (ie increase levels), causes more salts to be sucked out of the tubules.

Aldosterone is produced by the outer-section of the adrenal cortex in the adrenal gland, (which sits above the
kidney) and acts on the distal tubules and collecting ducts of the kidney.

When there is a lack of absorption of salts (ex. NaCl, NH3, K+ etc) , a signal goes to the hypothalamus which
triggers the secretion of aldosterone.
 High Salt Concentration: Aldosterone levels decreased, less salt reabsorbed, hence less water diffusing into
body cells.
 Low Salt Concentration: Aldosterone levels increased, more salt reabsorbed, more water diffusing into body
cells.

Present
information
to
outline
the
general
use
of
hormone
replacement
therapy in people who cannot secrete aldosterone:
–
This is a second developed technology, where the first was renal dialysis to aid people with affected kidneys.
–
Addison’s disease is a rare endocrine disorder occurring when the adrenal glands, seated above the kidney, fail to
produce enough aldosterone. Without aldosterone, the body would not be able to reabsorb salt (specifically sodium
ions) this would cause severe dehydration and excessive potassium loss which may cause brain damage and death.
–
The artificial replacement hormone is called Fludrocortisone, a drug that decreases the amount of salt the body
excretes. It is taken either orally or intravenously, patients are also advised by their doctors to increase their salt
intake.

Define
enantiostasis
as
the
maintenance
of
metabolic
and
physiological
functions in response to variations in the environment and discuss its
importance
to
estuarine
organisms
in
maintaining
appropriate
salt
concentrations:
–
Homeostasis is the process by which organisms maintain a relatively stable (constant) or almost constant, internal
environment.
–
Enantiostasis is the maintenance of metabolic and physiological functions in response to variations in the
environment.
–
The difference between the two, is the fact that homeostasis requires only a SPECIFIC internal condition for an
organism to function properly, example 37o is the required temperature for humans to function, enantiostasis is for
a VARIETY of internal condition which the function can function properly at, for example diving birds rely on
enantiostasis to function properly at extremely high and low pressure sky levels.

In homeostasis heat is 'acted against' by sweating etc, the pressure for birds isn't 'acted against'; it is 'adapted' to.
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–
An estuary is where a freshwater river meets and mixes with saltwater sea, and as such the salinity levels are
always changing dramatically. This is determined by the tide of the sea:

At high tide: sea water flows into the river mouth, creating an environment with higher salt concentration, hence
this salt water has the tendency to draw water out cells by osmosis (as the organism will be in freshwater)

At low tide: sea water flows out of the river mouth, and freshwater from the estuary is abundant, hence by
diffusion organism face the challenge of water moving into their tissue.
–
Organisms living in such an environment need to have mechanisms to cope with such changes in order to survive,
this is collectively called enantiostasis.
–
Enantiostasis is carried out by 2 process (these are present in normal homestasis conditions too, but they carry out
different roles):

Osmoconformation: process by which organisms tolerate the changes in the environment, and conform, or alter
the concentration of their internal solutes to match the external environment. Their metabolism can handle it.


Osmoregulation: is the control of the levels of water and mineral salts in the blood.
Process and analyse information from secondary sources and use available
evidence to discuss processes used by different plants for salt regulation
in saline environments:
–
Salt, even in small concentrations, has a damaging effect on cell metabolism.
–
Halophytes are plants that adapted and can tolerate high salt levelled environments, they are commonly found in
areas such as estuaries.
Grey Mangroves (Avicennia marina):
–

Salt Prevention: In its roots, it has a layer of cells that actively restrict the movement of salt into xylem vessels.

Salt Exclusion: Special glands in the mangroves can actively exclude the salt from the water, so that the water
absorbed has a lower salt concentration than the water in the environment.

Salt Accumulation: Salt is accumulated in old leaves that drop off, so that the salt is out of the plant’s system

Salt Excretion: Salt can be excreted from the underside of the leaves of the mangrove plants; salt crystals form
under the leaves.

Describe adaptations of a range of terrestrial Australian plants that assist
in minimising water loss:

Perform a first-hand investigation to gather information about structures in
plants that assist in the conservation of water:
–
Aim: To gather information from plant specimens about structures that assist in the conservation of water.
–
Equipment:

Different type of leafs that exist around the school (typical environment)

Hand lens
–
Safety:

Sun has strong UV light outside, sunscreen and hats should be worn.

Leaf can be diseased and can have splinters and can be sharp, gloves should be worn.
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–
Method:

Carefully, leaves where looked at for different 'prominent' features that could inhibit water loss, these where
then cross-checked with reliable sources.
–
Result:

Banksia:
 Leaves have sunken stomates: this reduces transpiration.
 Hard, waxy cuticles: this reduces the amount of water loss through transpiration.

Eucalyptus trees:
 Hard, waxy cuticles: this reduces the amount of water loss through transpiration.
 Leaves hang vertically: reduce sun exposure.

Spinifex grass:
 Have extensive root systems that can reach underground water.
 Leaves are also long and thin: to reduce water loss by transpiration.
 Can roll up to hide their stomata's: this reduces the amount of water loss through transpiration.

Analyse
information
from
secondary
sources
to
compare
and
explain
the
differences in urine concentration of terrestrial mammals, marine fish and
freshwater fish:
–
Freshwater Fish:

Osmotic Problem: Hypotonic to environment. Water diffuses INTO their bodies. Salts diffuses out.

Role of Kidney: Doesn’t drink continually, Kidneys removes excess water, while reabsorbing salts.

Urine: Large, dilute amount.
–
Marine Fish:

Osmotic Problem: Hypertonic to environment. Water diffuses OUT of their bodies. Salt diffuses in.

Role of Kidney: Continually drinks water, Kidneys reabsorb water, while actively secreting salts.
(Salt is also excreted across gills)

–
Urine: Small, concentrated amount.
Terrestrial Mammals:

Osmotic Problem: Water needs to be conserved.

Role of Kidney: Regulates concentration of blood, while at the same time excretes urea and conserves water.

Urine: Concentration changes with the availability of water, as well as temperature and water loss through
sweat. Water levels in blood rise, urine amount rises, and concentration decreases and vice versa.

Explain
the
relationship
between
the
conservation
of
water
and
the
production and excretion of concentrated nitrogenous wastes in a range of
Australian insects and terrestrial animals:
–
Ammonia is the direct result of amino acid breakdown (deamination) and is a waste product of all organisms. It is
very water soluble, but VERY toxic, and must be removed quickly, or changed to a less toxic form.
–
The removal of ammonia would require large volumes of water, and this is not possible for animals or insects that
seek to conserve water.
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
Aquatic Animals and Fish: These organisms directly release AMMONIA into the environment. This uses a lot
of water, but they have no need to conserve it. Ammonia is very water soluble and is excreted through the gills.

Terrestrial Animals: Releasing ammonia would be impossible due to lack of water. Instead, land-dwellers
change ammonia into less toxic forms and release it periodically. Mammals change it into UREA and release it
as urine (ex; kangaroos, wallabies, hopping mice and koalas). Australian animals release very concentrated
urine, and are able to tolerate high levels of urea in their bodies.

Birds: Birds change ammonia into URIC ACID, a whitish paste which uses hardly any water. This is lighter
than using urea, and helps in flight.

Insects: Insects also change ammonia to URIC ACID.
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9.2 - Maintaining a Balance:
1. Most organisms are active within a limited temperature range:
• Identify the role of enzymes in metabolism, describe their chemical
composition and use a simple model to describe their specificity in
substrates:
– Role of enzymes in metabolism:
• Metabolism refers to all the chemical reactions occurring in organisms
• Anabolism- synthesis of larger molecules from smaller ones
• Catabolism- Breakdown of larger molecules into simpler ones
• Examples of cellular processes involved in metabolism- respiration, glycolysis,
photosynthesis, protein synthesis
• Chemical reactions needed to:
∗ Obtain energy
∗ Build new chemicals for growth and repair of cell
∗ Make substances needed by other cells
• Enzymes are biological catalysts which accelerate chemical reactions
∗ Without enzymes, metabolism would be too slow to support life
∗ Important in cells as heat damages living cells
• Lowering of activation energy
∗ Enzymes do not produce activation energy rather they reduce the amount of
activation energy
∗ Lower the activation energy to start a reaction so that the reaction can
proceed quickly without a change in temperature
• Example of enzyme (Sucrase)
∗ Sucrose- Sugar used in sweets and cakes- obtained by crushing out the
contents of phloem tissue of sugarcane plants
∗ This carbohydrate consists of 2 simpler sugar molecules- one glucose and one
fructose molecule
∗ Sucrose- too large to be absorbed into the bloodstream from digestive
system
∗ Broken down in the small intestines into its 2 component sugars by an
enzyme called sucrose
∗ Molecules of glucose and fructose are small enough to be directly absorbed
through the membranes of the digestive system into the blood stream
Substrate
Products
Sucrase enzyme present
Sucrose molecule
•
Glucose + Fructose
Another example (Maltase)
∗ Maltose sugar- found in a lot of sweets
∗ Needs to be digested using an enzyme before it can be absorbed into the
bloodstream
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Substrate
Products
Maltase
Maltose molecule
•
•
•
Glucose + Glucose
Enzymes are very specific
Each enzyme changes the rate of one kind of chemical reaction only
Many different enzymes within each organism to control all the reactions that are
part of the organism’s metabolism
•
Chemical composition of enzymes:
• Most enzymes are made up of protein
• Proteins are composed of long chains of amino acids joined together by
peptide bonds
• 20 different amino acids make up proteins and enzymes in organims
• These long chains are called polypeptide chains
• Proteins consist of one or more polypeptide chains
• The shape of each enzyme makes it able to take part in a specific kind of chemical
reaction
Structure of enzymes:
• In enzymes, the polypeptide chain is folded into a 3-dimensional globular
• shape
• Active site- where the enzyme binds to the substrate
• The substrate are the molecules the enzymes acts upon
Specificity of enzymes:
• Enzymes are highly specific in their action; this means that each enzyme acts
• on one substrate only
• This is because the shape of the active site of the enzyme matches the shape of the
substrate material
• The molecules the enzyme act upon are called the substrate
• The substrate molecules bind to the active site and a chemical reaction occurs
• The products are the substances that the substrate(s) become. One substrate
• can be split, or two substrates can be joined
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Enzyme models
The Lock and Key Model
• Enzyme must fit the shape of the substance for it to influence a chemical reaction
• suggests that the substrate fits exactly into the active site of the enzyme like a key
fits into a lock. It assumes that the enzyme had a rigid and unchanging shape.
• The enzyme is sometimes referred to as the 'lock' and the initial reactant substrate
molecule as the 'key'
• This is where only one small part of the enzyme molecule can form a complex with
the substrate. This part of the molecule is called the active site.
• Only a specific substrate(s) can bond in that site and this makes the enzyme specific
to that substrate.
The Induced Fit Model
• states that the binding of the substrate to the enzyme ‘induces’ a temporary change
in shape of the enzyme.
• The new shape of the enzyme better accommodates the shape of the substrate and
a reaction occurs.
• It suggests that the active site continues to change until the substrate is completely
bound to it, at which point the final shape and charge is determined.
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Identify the pH as a way of describing the acidity of a substance:
• pH means the power or concentration of dissolved hydrogen in the solution
• The substance that makes a solution acidic is hydrogen ions
• pH is a measure of the acidity or the alkalinity of a substance
• The pH scale is from 0 to 14: a pH of 7 is neutral (pure water); above 7 is alkaline/
basic and below 7 is acidic
• On pH scale a change in one pH unit is a change in concentration of 10 times e.g. pH
14 is 10 times more basic than pH 13
• pH of a solution can be found by:
1. Using an electronic probe or sensor
2. Using universal indicator
Factors affecting enzymes
identify data sources, plan, choose equipment or resources and perform a first-hand investigation
to test the effect of:
– increased temperature
– change in pH
– change in substrate concentrations on the activity of named enzyme(s)
(IN BIO PRAC BOOK)
1. Changing pH:
• Many enzymes work best at a pH that is just slightly alkaline
• Decreasing or increasing acidity from the optimum (the best possible) pH reduces
the activity of an enzyme.
• Enzymes change shape and are denatured (take away natural qualities) when the pH
varies too much from their optimum
• Any change in pH above or below the Optimum will quickly cause a decrease in the
rate of reaction, since more of the enzyme molecules will have Active Sites whose
shapes are not, or at least less, Complementary to the shape of their Substrate.
• Small changes in pH above or below the Optimum do not cause a permanent change
to the enzyme, since the bonds can be reformed but extreme changes are
irreversible.
2. Changing temperature
• Decreasing temperature decreases the activity of an enzyme- molecules have
lower energy
• Increasing temperature increases its activity until the shape of the enzyme
begins to alter
• If the temperature is high enough to permanently change the enzyme’s
shape then the enzyme is denatured and can no longer catalyse the reaction
• Human optimum temp- 35-40’c
• Enzymes that are partially denatured by heat may regain their correct shape
on cooling but complete denaturation is irreversible
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3. Changing substrate concentration
• Decreasing the concentration of substrate decreases the activity of an
enzyme
• Increasing the concentration of substrate increases its activity until all the
enzyme is involved in catalysing reactions
• If substrate concentration is increased an enzyme concentration stays the
same then the rate of reaction will increase to a point and then remain
constant caused by all active sites on the enzyme molecule being occupied
known as the saturation point. A further increase in substrate molecules
cannot increase the rate of reaction cause no more active sites available.
Cofactors- inorganic chemicals that help catalyse, either by binding tightly to the enzyme’s
active site as permanent residents or by bonding loosely alone with the substrate
Coenzymes- perform same function but are organic molecules
Enzyme inhibitors- certain chemicals inhibit the action of specific enzymes, either by
attaching to the active site or changing its shape.
Explain why the maintenance of a constant internal environment is important for optimal
metabolic efficiency:
– Enzymes are essential for proper metabolic function in an organism
– However, enzyme efficiency is affected greatly by certain factors
– These include:
_ Temperature
_ pH
_ Substrate concentration
– Enzymes work best within a limited range therefore, a constant and stable internal
environment is needed so that enzymes will always be working at an optimum rate, and thus
metabolism will be at an optimum efficiency
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Describe homeostasis as the process by which organisms maintain a relatively stable
internal environment:
– Homeostasis is the process by which the body maintains a stable internal
Environment despite changes in the external environment
– Multicellular organisms regulate their internal environment in order to remain
Healthy
– The internal environment of cells are kept within certain limits by the coordinating
systems of the body
– These systems monitor all the activities of cells, their requirements and the wastes they
produce
-Homeostasis keeps conditions as close to the optimum as possible so that the organism’s
metabolism can operate as efficiently as possible
- Through homeostasis, organism maintain an internal equilibrium (stableness) by adjusting
physiological processes through the use of feedback systems
-Feedback systems are a self regulating mechanism that maintains homeostasis (a balance).
-Role: maintain conditions and reaction within the small range to sustain life
-Consists of 3 main parts:
1. Receptor- monitors/ detects changes in the internal and external environment
2. Control centre (hypothalamus)- monitors information passed from the receptor and
determines and appropriate response.
3. Effectors- carries a message from the control centre
Explain that homeostasis consists of two stages
_ Detecting changes from the stable state;
_ Counteracting changes from the stable state:
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If homeostasis is to be maintained; the body must be able to detect stimuli that indicate a change in
internal / external environment.
Stage 1)– Detecting Changes:
The body needs to maintain a ‘stable state’ in order to function properly Made possible by
the presence of receptors in living organisms
_Receptors in body tissues detect changes in the environment (internal & external).
-
Mechanoreceptors
Photoreceptors
Chemoreceptors
Thermoreceptors.
Messages sent along neurones (nerve cells) as an electrochemical impulse. Brain receives &
interprets message. Receptors detect a change in the variable.
_ Changes, or deviations, from the stable state are caused by the external and internal
environment
_ Any change, or information, that provokes a response is called a STIMULUS
_ RECEPTORS detect stimuli; organisms then react to the change
_ There are two types of receptors within the body:
_ Disturbance receptors: These receptors, usually in the skin, detect changes caused by the
external environment
_ Misalignment receptors: These receptors detect changes from the body’s stable state.
_ Examples of external stimuli: light, day length, sound, temperature, odours
_ Examples of internal stimuli: levels of CO2, oxygen levels, water, wastes, etc.
Stage 2)-Counteracting Changes:
•
•
•
•
•
•
•
Brain responds to message by sending a nervous message to an effector to counteract the
changes in the environment.
Effectors counteract the change (muscle / gland).
After receptors detect changes, organisms can then react to the change.
When a change affects the organism’s normal/ stable state, the response is homeostatic.
This type of response will counteract the change to ensure the stable state is
maintained brought about by effectors
EFFECTORSbring about responses to stimuli Can either be muscles or glands.
Muscles bring about change by movement.
Glands bring about change by secreting chemical substances
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Gather, process and analyse information from secondary sources and use available evidence to
develop a model of a feedback mechanism
Homeostasis is maintained by feedback mechanisms. The response to a change may involve negative
or position feedback:
- Negative feedback acts to counteract any changes in the cells. For example, if blood sugar levels
are high the response counteracts this change by reducing blood sugar levels.
- Positive feedback operates by reinforcing the changes in the cell
No Change
Figure 2: Homeostatic control of
blood glucose levels
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Negative feedback:
• A specific change that results in a response opposite to the initial situation
• E.g. in humans if body temp becomes too low (stimulus), the person may shiver
(response). The shivering generates heat and the body becomes warmer (new
stimulus). The feedback mechanism monitors the rise in temperature and will cause
the opposite to the initial response- it will stop the shivering
Positive feedback
• The monitoring will re-enforce and amplify the situation, causing more of the same
situation to take place
• E.g- process of labour. Once labour begins, it needs to be completed quickly to avoid
unduly stressing both mother and baby. The pressure of the baby’s head near the
opening of the uterus stimulates uterine contractions, which cause greater pressure
against the uterus opening, heightening the contractions which causes still greater
pressure.
Outline the role of the nervous system in detecting and responding to environmental
changes:
– The nervous system works to regulate and maintain an animal’s internal environment and
respond to the external environment
- Important in homeostasis
- Sensory nerves of peripheral N.Sdetects changes. They are the receptors and they
carry the message to the brain
- CNS(Brain) – response to counteract the change is decided. message is sent back to
the affected body parts via the motor nerves of the P.N.S. These are the effectors
-Role of nervous system:
1. Detect information about animals internal and external environment and then
coordinates the body’s response to these changes
2.Transmit information to a control centre
3. Information processed in the control centre, generates a response
– The nervous system is made up of two parts:
_ Central Nervous System:
- acts as the CONTROL CENTRE for all of the body’s responses.
- It coordinates all the responses.
- made up of the brain and the spinal cord.
- receives information, interprets it and initiates a response.
- Hypothalamus one of these regions of regulate release of hormone responsible for
-
controlling many variables (major role in maintaining homeostasis).
-Thalamus receives impulses from sensory neurones, directs them to parts of the
brain.
_ Peripheral Nervous System:
- This is a branching system of nerves that connects receptors and effectors.
- This system transmits messages from the central nervous system and back.
- It acts as a communication channel.
- Composed of all neurons outside the CNS
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-
Includes sensory and motor neurons
Sensory neurons- transmit messages to the CNSfrom receptor organs
Motor neurons- Transmit messages from the CNS to the effector organs such as
muscles
– The nervous system works closely with the endocrine system- This system produces
hormones in response to certain stimuli in order to maintain homeostasis
Identify the broad range over which life is found compared with the narrow limits for
individual species:
– Ambient temperature is the temperature of the environment
– The range of temperatures over which life is found is broad compared to the
narrow limits for individual species
– Life can only exist between temperatures because:
• Enzymes that catalyse the reactions of metabolism are very temperature
sensitive- stable but slow if too cold and unstable and denature when too hot
• Many cell membrane proteins only function properly of they are floating in
the lipid bilayer
- Organisms live in environments with ambient temperatures ranging from less than 70 degrees (at the poles) to over 50 degrees (in deserts).
- Individual organisms cannot survive this whole range of temperatures.
To survive, organisms must be able to live within the temperature range of their
local environment.
- This means that life is found in a very wide range of temperatures, but individual
species can only be found in a narrow temperature range in which they can survive
(Eg humans can only survive unclothed and unsheltered from 27°C to 43°C) because
of certain behavioral, structural and physiological adaptations
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Compare responses of named Australian ectothermic and endothermic organisms to
changes in the ambient temperature and explain how these responses assist in
temperature regulation:
– ECTOTHERMS(cold blooded) organisms that have a limited ability to control their body
temperature. Their cellular activities generate little heat. Their body temperatures rise and
fall with ambient temperature changes. Most organisms are ectotherms.(cold blooded)
Examples are plants, all invertebrates, fish, amphibians and reptiles
– ENDOTHERMSare organisms whose metabolism generates enough heat to maintain an
internal temperature independent of the ambient temperature (warm blooded)
Examples are birds and mammals
Heat exchange with the environment:
All organisms exchange heat with their external environment in 4 ways:
1. Conduction: direct transfer of heat from the environment to the body surface
2. Convention: transfer of heat by the movement of air or liquid past the body surface
3. Radiation: Transfer of heat by electromagnetic waves between objects that rent in
contact
4. Evaporation: heat loss form the surface of a liquid when it changes to a gas
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Behavioural adaptations:
- Ways that organisms behave in order to help it survive in its environment
- E.G. Migration, nocturnal activity, burrowing, basking
Structural adaptations:
- Physical features of the organism that help it survive e.g. shape, appearance,
structure
• Insulation-Fur in mammals & feathers in birds trap a layer of air that slows down
heat exchange with the external environment.
- Thickness of fur / feathers can be changed with changing seasons.
- Subcutaneous fat traps heat beneath skin.
- eg. Cockatoo.
- Can contract muscles to lift feathers up in cold conditions.
- eg. Whales.
- Have layer of blubber to prevent transfer of heat to water.
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• Piloerection:
- ‘Hair standing on end’
- Important for most mammals.
- Trapped air beneath hair/ fur acts as insulation.
- Sympathetic neurones carry impulses from hypothalamus to base of
each hair, muscle contracts, hair stands on end.
• Surface area : volume:
- Large volume with small surface area loses heat less efficiently than
- large surface area & small volume.
- E.G. Blubber as insulation in whales/ dolphins, animal fur
Physiological adaptations:
- a change metabolism or biochemistry to deal with an environmental problem i.e. realted to
-
the functioning of the organism body
E.G. endotherms speed up their metabolism in cold environment or hibernate in winter
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Example of an Australian endotherm and ectotherm
Name of
Endothermic or Adaptation/ response
organism
ectothermic
Red
kangaroo
Endothermic
Keeping warm:
• Produces heat to keep warm
using its metabolism
• Insulating covering of fur
• Obtains heat by being active
and in direct sunlight
Keeping cool:
• Less active during warm
periods of the day
• Seeks shelter under shade
• Pants (rapid, shallow breaths),
so that heat is lost from its
nasal passages (air passages
inside its nose)
• Licks its forearms so saliva
evaporates and cools the skin
and blood below
• Sweats through its skin when
it is active
Australian
diamond
python
Ectothermic
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Cold conditions:
• Lies on eggs and shivers to
create more heat within the
body
• Dark in colour to absorb heat
and therefore can tolerate
colder temperatures than
most snakes
• Bask in sun to raise body temp
• Hibernate during winter
• Migrate to warmer areas
Warm conditions:
• Nocturnal- hunting at night
• Burrowing during the day
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Behavioral,
Structural,
Physiological
•
Physiological
•
Structural
•
Behavioral
•
Behavioral
•
Behavioral
•
Structural
•
Behavioral
•
Physiological
•
Physiological
•
Structural
•
•
•
Behavioral
Behavioral
Behavioral
•
•
Behavioral
Behavioral
Page 14 of 51
Identify some responses of plants to temperature change:
Enzymes in plants have same characteristics to those in animals. Have optimum temperature at
which maximal efficiency occurs. Plants tend to maintain temperature in optimal range for optimal
metabolic activity to occur & to minimise damage. Optimal temperature is also required for
germination of seeds & growth
Responses to change;
- In extreme heat or cold, plants can die, but leave behind dormant seeds.
- Plants may die above the ground, but leave bulbs, roots, rhizomes or tubers to survive
underground. These then sprout when favourable conditions return
- Vernalisation: this means that some plants need exposure to cold condition before they can
flower
- Seed dispersal is also stimulated sometimes by fire
Leaf Fall
•
•
Plants reduce their surface area exposed to heat by dropping their leaves.
This also reduces the amount of water that is lost through transpiration.
Radiation
•
Some plants living in very exposed areas, such as sand dunes, reduce the amount of
heat absorbed by having shiny leaves that reflect solar radiation.
Heat-Shock Proteins
•
These are proteins produced by plants that are under stress from very high
temperatures. These molecules are thought to stop enzymes denaturing, so normal
cell reactions can continue.
Transpiration
•
•
The movement of water up the plant from the roots to the leaves via the
transpiration system serves to cool the plant during hot conditions.
The evaporation of the water from the stomata of the leaves also serve to cool the
plant.
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Die back
•
In harsh conditions the shoots and leaves of a plant may die, but left in the soil are
bulbs, roots or rhizoids that will begin to grow again when favourable conditions
return.
Orientation of Leaves
•
Vertical orientation of some leaves has the advantage of reducing the amount of leaf
surface area in contact with sun rays, e.g. Eucalyptus leaves hang vertically.
Seed Dispersal
•
•
Some Australian natives require extremely high temperatures, such as those
produced by a fire, to germinate their seeds.
Plant seeds from species such as Banksia ericifolia are only able to open their seed
coats when they are exposed to fire.
Vernalisation
•
This is when plants must be exposed to cold conditions to produce flowers and
therefore reproduce. Plants in alpine regions use vernalisation to reproduce when
conditions are more favourable at the end of winter.
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•
∗
The presence of cold conditions will stimulate flowers to grow, and when spring
approaches they are almost mature.
Many
native
plants
They
flower
afterrespond
fire to high temps caused by bushfires by:
Have fruits that open and release seed after fire
Have seeds that need to be heated in a fire to germinate
EXAMPLES:
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Alpine groundsel
∗
∗
∗
∗
∗
∗
∗
Australian plant- Kosciuszko area of NSW and victoria
Air temp in those areas vary between -10’c and 3’c
Plant is small so it is buried by snow during the coldest parts of the year
Snow cover protects the plant, keeping its temp around 0’c
Leaves and stems remove the moisture to reduce the risk of damage to the cells
caused if water freezes inside them
Hairy layer on leaves and stems reduces likelihood of freezing (and reduces water
loss)
Roots and sub-soil buds are close to the surface where the soil rarely freezes
Mulga
∗
∗
∗
∗
Australian tree that lives in dry areas of most states
Leaves have a thick silvery cuticle (outer layer) that reflects and insulates against
heat (as well as reducing water loss)
Shape of tree means that water falling on the plant runs down leaves and stems to
the base of the tree to be absorbed by its roots
Adequate water is essential to prevent overheating of the plant tissues
Gather, process and analyse information from secondary sources and use
available evidence to develop a model of a feedback mechanism:
– Homeostasis involves the detection of the change in the environment and the
response to that change
– The mechanism that brings about this change is called FEEDBACK
– In feedback systems, the response alters the stimulus
– In living organisms, the feedback system has 3 main parts:
_ Receptors: A type of sensor that constantly monitors the internal environment
_ Control Centre: Receives info from the receptors and determines the response
_ Effector: Restores the set value. Keeps environments stable.
(IN BIO PRAC BOOK- RESEARCH TASK)
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(In BIO PRAC BOOK)
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2. Plants and animals transport dissolved nutrients and gases in a fluid
medium:
Identify the forms in which each of the following is carried in mammalian
blood:
_ Carbon Dioxide
_ Oxygen
_ Water
_ Salts
_ Lipids
_ Nitrogenous wastes
_ Other products of digestion
•
The mammalian circulatory system has four main functions:
1. TRANSPORT: The major function of the circulatory system is to transport
water, gases, nutrients and wastes.
2. BLOOD CLOTTING: This complex mechanism repairs damage to blood vessels
and seals wounds to prevent loss of blood
3. DEFENCE AGAINST DISEASE: White blood cells help to fight infection in the
body. Antibodies provide immunity against further attack
4. TEMPERATURE REGULATOIN: The flow of blood distributes heat around the
body. Control of the amount of blood passing close to the skin helps control
heat loss from the body.
Composition Of The Blood:
• PLASMA:
make up 55% of the volume of the blood.
sticky, straw-coloured and slightly salty.
Substances transported in the plasma include waste minerals
It is made up of 90% water. Other substances found in the plasma include:
_ salts (as ions)
_ plasma proteins (including antibodies, clotting factors, lipid transporters)
_ products of digestion (sugars, amino acids, hormones, etc)
_ waste products (carbon dioxide, urea)
• BLOOD CELLS:
Red Blood Cells:
Also called erythrocytes
Shape is bi-concave discs, thinner at centre than at edges
Contains the pigment haemoglobin
Their function is to transport respiratory gases; mainly oxygen
They have no nuclei; they only live for 3 months. After this they are destroyed in the
liver or spleen.
They are produced in the bone marrow
6-8um
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_ White Blood Cells:
Also called leucocytes
Shape is irregular; can change shape
Function: to defend against disease
The two main types of leucocytes are phagocytes and lymphocytes
1. PHAGOCYTES surround and ingest foreign bodies, bacteria and dead cells and collect
around areas of infection or injury
2. LYMPHOCYTES act only on specific foreign material. They make antibodies which help
the body’s defence against disease.
much less common than red blood cells
They are the largest blood cell
They have nuclei, unlike red blood cells
They are produced in the lymph nodes and glands.
PLATELETS:
They are fragments of old cells made in the bone marrow
function is to make the blood clot
Smallest blood cell
No nucleus
– Transporting Substances In The Blood:
CARBON DIOXIDE:
• Most carbon dioxide enters the red blood cells and is combined and altered to form
bicarbonates
• It is produced as a waste product of respiration in body cells. After entering the
bloodstream it may:
1. Be converted into carbonic acid which is then changed into hydrogen carbonate ions. This
change from carbon dioxide to carbonate ions happens on the red blood cells. Then they are
transported in the plasma (only 70% of the carbon dioxide).
2. Binds to haemoglobin in erythrocytes forming carbaminohaemoglobin
(only 23% of the carbon dioxide).
3. Be dissolved directly in the plasma (only 7% of the carbon dioxide).
OXYGEN:
1. Oxygen is needed in the body for respiration. It is brought in across
the respiratory surfaces of the lungs.
2. Some are dissolved directly into the plasma as oxygen gas
3. It binds with haemoglobin in red blood cells, forming oxyhaemoglobin.
- O2 diffuses from the external environment into the blood; through alveoli.
- Diffuses from air into blood due to concentration gradient.
- Less in blood than in the air ... moves into the blood.
- Circulates throughout body to cells via circulatory system.
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• In the lungs:
- When O2 concentration is high;
Hb + 4O2
Hb(O2)4
Haemoglobin + Oxygen
oxyhaemoglobin
• In body tissues:
- O2 concentration is low
Hb(O2)4 Hb + 4O2
WATER:
1) Water is the solvent of plasma
2) made up of 90% of the blood plasma hence carried as water molecules in the plasma
3) It makes up 60% of the volume of blood
SALTS:
1. Carried as ions dissolved in the plasma
2. E.G. sodium, potassium, magnesium, etc
LIPIDS:
1lipids are encases in a protein coat, and becomes lipoproteins dissolved in plasma
2.Digested lipids are changed into triglycerides (this happens in the lining of the small
intestine).
3. Triglycerides, together with phospholipids and cholesterol, are wrapped in
a coat of protein to form a package called a chylomicron.
3.These are released into the lymph and eventually pass into the veins
NITROGENOUS WASTES:
1. Wastes such as ammonia are changed in urea
2. Uric acid are dissolved directly in the plasma
OTHER PRODUCTS OF DIGESTION:
1. Includes amino acids, sugars, glycerol and vitamins
2. They are mainly water soluble and transported and dissolved directly in the plasma
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Explain the adaptive advantage of haemoglobin:
– Structure of haemoglobin:
_ Globule-shaped protein containing four polypeptide sub-units
_ 4 polypeptide chains:
1. 2 identical alpha chains
2. 2 identical beta chains
_ Each polypeptide encloses an IRON-containing structure, called the HAEM
group (4 HAEM groups altogether)
_ The haem groups combine with the oxygen.
– Oxygen fuses with haemoglobin where the concentration of oxygen in the blood
is low; that is, in the lungs.
– It makes an unstable compound – oxyhaemoglobin
– One haemoglobin molecule can carry four molecules of oxygen
– Where oxygen is needed, the oxygen bond easily breaks and the oxygen is used.
Adaptive Advantage:
_ Mammalian cells need a lot of energy and therefore must have a continual
supply of OXYGEN for RESPIRATION
energy through respiration
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_ This ability of blood to carry large quantities of oxygen gives mammals a
considerable survival advantage e.g
•
•
•
-
Organisms with blood (containing haemoglobin) are able to deliver oxygen to cells more
efficiently than other organisms with blood that has no haemoglobin.
The net effect is that these organisms are more effective operators in a given environment
than their competitors.
This higher rate of respiration allows an increase in the amount of released energy which
can allow the animal to: move faster, grow large, live in cold areas and give mammals the
ability to maintain a constant body temperature enabling them to be active in a large
temperature range for example.
The structure of haemoglobin is also an adaptive advantage because it is a type of molecule
that can combine with oxygen loosely at the respiratory surfaces and then release the
oxygen freely in capillaries.
Compare the structure of arteries, capillaries and veins in relation to their
function:
– ARTERIES:
_ Carry blood away from heart (high blood pressure)
_ The pressure created by the heart’s pumping creates great stress in the arteries
_ This is why the arteries are thick walled, elastic and muscular.
_ The arteries are not motionless; they have muscle fibres in them which can
contract and relax.
_ This contracting maintains the pressure on the blood, so that the blood travels
in spurts towards the body tissues (the contracting and relaxing also creates
the pulse on your wrist or neck).
_ The muscle fibres of the arteries also maintain the rate of the flow of blood.
_ Arteries usually carry oxygenated blood
_ Arteries lead to arterioles (small arteries).
CAPILLARIES:
_ Capillaries are an extension of the inner layers of the arteries and veins
_ They join arterioles and venules (small veins)
_ Capillaries are only one cell thick, and are so narrow, that only one red blood
cell can pass at a time.
_ Capillaries surround all tissue cells
_ Thus, they provide a very large surface area over which exchange of materials
between blood and body can occur.
VEINS:
_ Veins carry blood back to the heart
_ The capillaries join to form venules, which join to form veins
_ Veins are not under a lot of stress - blood pressure is low
_ This is why they have thinner walls than arteries, less muscle and a wider
diameter.
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_ Since there are no thick muscular walls to keep the blood pulsing along, the
veins have a series of valves which prevent the blood from back-flowing on its
way back up to the heart.
_ The veins also run through muscles, such as your leg muscles, and as you use
these muscles, they press on the veins, pushing blood through the veins.
Describe the main changes in the composition of the blood as it moves around the body
and identify tissues in which these changes occur:
PULMONARY CIRCUIT:
• _ Blood flows from heart to lungs and then back to the heart
• _ Blood is under lower pressure than in the systemic circuit
• _ However, the rate of blood flow is faster
• _ Very little body fluid is formed
• _ The blood, having just returned from the body, contains high CO2 levels and
• low oxygen levels
• _ In the lungs, blood loses CO2 collects oxygen
SYSTEMICCIRCUIT:
• Blood flows from the heart to the body (except the lungs) and returns back to the
heart
• Blood is under high pressure due to contractions of the left ventricle of the heart,
but pressure gradually lessens
• Blood pressure forces some fluid out of blood to become body fluid
• In the tissues:
1. Blood gives up oxygen and other ions and nutrients
2. Waste products, eg urea, CO2, enter the blood
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KIDNEYS:
• Blood loses urea and has the composition of water and salt balanced
INTESTINES:
• Blood collects the products of digestion
• Levels of glucose, lipids, and amino acids rise
LIVER:
• Regulates the level of glucose in blood
• Excess glucose is converted to glycogen and is stored
• Converts excess amino acids to urea
Changes in blood composition
1) Excess vitamins broken down in the liver to form urea
2) Liver stores salt in the form of glycogen
3) Water, old red blood cells and glucose are broken down by liver and is .: expected to
be less of them in the blood leaving the liver
4) Amino acids leaves the blood via the kidney as it is toxic
5) Excess bicarbonate leave the blood through the kidney
6) Carbon dioxide in the form of dissolved bicarbonate ions leaves the blood through
the lungs as it would otherwise make the blood too toxic
7) Blood entering the right side of the heart is high in carbon dioxide and low in oxygen
8) It is sent to the lungs where it picks up oxygen and deposits carbon dioxide
9) Blood leaving the left side of the heart id high in oxygen and low in carbon dioxide
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Outline the need for oxygen in living cells and explain why the removal of carbon dioxide
from cells is essential:
– All living cells need oxygen for respiration to produce energy that is required to maintain metabolic
processes, to survive and reproduce
– As a result of respiration, carbon dioxide is produced
–if a lot of carbon dioxide is produced, the body cells (and the
blood and lymph) will become acidic
Describe current theories about processes responsible for the movement of
materials through plants in xylem and phloem tissue:
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In XYLEM:
•
Xylem cells are dead at maturity, so physical processes are responsible for the upward
movement of water and minerals. Passive transport and one-way only (up).
• Transport of water is passive and depends on transpiration and the physical properties of
water. A current theory, called the cohesion-tension theory:
1) Cohesion: Water molecules tend to bind together, forming a continuous Column in the xylem,
which replaces any loss
2)
Transpiration: Water is evaporated through stomates and replaced by water from leaf cells
and xylem tissue.
3) Tension: Water moves up the xylem like wire being pulled up, due to cohesion.
4) Adhesion: When the pull stops, water sticks to the sides of the tube and does not fall down capillarity.
1. Transpiration: Evaporation of water from the leaf cells through the stomates initiates the
pull of the TRANSPIRATON STREAM. Water is then drawn up the xylem tubes to replace this
loss
2. Cohesion: Water molecules tend to bind together, forming a continuous column in the
xylem, which replaces any loss
3. Adhesion: Water molecules stick to the sides of the xylem tubes (cellulose walls).
In phloem:
• Movement of materials through phloem is called translocation.
• Materials move both up and down the stem.
• Materials are distributed especially to the growing points and reproductive structures,
including developing fruits and seeds.
• Flow of materials in the phloem is an active process that requires energy.
• It is thought to occur by a mechanism called the source-path-sink system and Is driven by a
gradient generated osmotically.
‘Source-to-sink’ mechanism:
• Sugars can move via translocation in any direction but always from a place where they are
abundant (sugar source) to a place they are needed (sugar sink).
• Sieve elements accumulate solutes such as sugars from leaves.
• Companion cells also accumulate solutes & deliver them to sieve elements.
• At these sites the sugar concentration is high causing entry of water.
• The resulting pressure causes water and solutes to flow along under the force of turgor
pressure to the places where sugar is being removed (sink).
Theory 1: the source-path-sink system
• Sugars and other mineral nutrients are ‘loaded’ into phloem sieve tubes of the leaves.
• As sugars enter the phloem the concentration of phloem sap increases causes the entry of
water by osmosis from the surrounding cells.
• This resulting pressure causes water and dissolved solutes to flow towards a sink.
• A sink region of the plant where sugars and other nutrients are actively removed from the
phloem.
• As sugars move out of the phloem, water flows out with them. This reduces the pressure in
the sieve cells at the sink region.
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Theory 2:
• sugars moved through the phloem by cytoplasmic streaming and active diffusion within the
sieve tubes.
Analyse information from secondary sources to identify the products extracted from donated
blood and discuss the uses of these products:
While whole blood is used for some transfusions, several different things are often extracted to
make its usage more effective and efficient. These are:
* Red blood cells - used in people who have problems with transporting
•
oxygen (ie – anaemia), or to help replace blood cells following significant bleeding from
trauma or surgery. It increases haemoglobin levels while not increasing blood volume.
* White blood cells- used for patients who are not producing their own
•
white blood cells to assist patients to fight infection
* Platelets - used to promote blood clotting and control bleeding. It is often
•
used for leukaemia and bone marrow transplant patients.
* Stable protein plasma is used in emergencies before whole blood
•
becomes available. It is also used in patients with burns, who tend to lose fluid rather
than whole blood. Plasma is also further processed to make:
- Cryoprecipitate which contains blood clotting proteins. Used for liver
transplant patients, treatment of massive bleeding and patients who have
deficiencies of the blood clotting proteins (Haemophilia A).
- Cryosupernate which undergoes further processing to produce Anti D
(prevents Rhesus in newborns), Immunoglobulin (carries antibodies against
common infectious diseases) and Intragam (boosts immune system, used in
treatment of some muscle and nerve disorders).
* Clotting factors can be used in people with severe bleeding problems, such as
•
haemophilia.
* Immunoglobins are antibodies used to protect people against infectious diseases
•
such as hepatitis, chickenpox and tetanus & in people with immune system problems,
such as AIDS.
* Serum albumin is used in people with low plasma protein levels, such as those
•
with liver/ kidney disease. It is used to restore blood volume in the treatment of burns and
severe shock.
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Name of
product
Fresh
Frozen
Plasma
Description
How it is
prepared
Shelf
life*
Fresh frozen Separated
12
plasma.
from whole
months
Replaces
blood by
at -25'C
coagulation
centrifugation
factors if
platelet
concentration
is not
available or
appropriate
Helps
Centrifuge
Platelet
clotting of
plasma and
concentrate blood, used
remove
to treat
platelets
patients with
dysfunctional
platelets,
leukaemia
patients and
those with
other form of
cancer
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CrossRisk of
Side effects*
matching infectious
needed?* agents?*
No
Low
Haemoglobin
(rare)
transfusion
related lung
injury
No
Yea
Incorrect use
(highest
leads to
risk blood haemorrhage
product)
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Table - Products of donated blood
3.Plants and animals regulate the concentration of gases, water and waste products of
metabolism in cells and in interstitial fluid
Explain why the concentration of water in cells should be maintained within a narrow
range for optimal function
• Water makes up around 70-90% of living things; it is essential for life.
• essential that the concentration of water in cells is kept constant as even small
increases or decreases can lead to death.
• Water solvent of all metabolic reactions in living cells, and sometimes directly
takes part in it (eg. Respiration).
• It is a solvent in which all metabolic reactions take place.
• It is a transport medium for sugars, salts, hormones, wastes.
• The concentration must be kept within a narrow range as the amount of water
affects the concentration of solutes, which affects ability to diffuse in & out of cells.
• Lack of water causes dehydration.
• Blood pressure falls and circulation fails.
• It can absorb and release large amounts of heat and requires a large amount of heat
to vaporize, and therefore plays an important role in regulating temperature.
• It maintains the shape of the cell membrane – too much water can cause a cell to
burst and it cushions and protects body organs
• The osmotic pressure of living tissue can also affect the pH in cells—for example, too
little water leads to an increase in the concentration of solutes such as carbon
dioxide and this in turn lowers pH. Both osmotic pressure and pH must be
maintained within a narrow range so that enzymes can function under optimal
conditions, to allow effective metabolism.
RECALL:
• Isotonic: Concentration of solutes outside the cell is the same as inside the cell. No
overall movement of water.
• Hypertonic: Concentration of solutes is greater outside the cell than inside. Water
tends to move out of the cell.
• Hypotonic: Concentration of solutes is greater inside the cell than out. Water tends
to move inside the cell.
• Living cells work best in an isotonic environment.
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Explain why the removal of wastes is essential for continued metabolic activity
• Any accumulation of wastes may be toxic to cells and so metabolic wastes must be
removed from the body to maintain homeostasis.
• If wastes not continuously removed, their levels in the body will increase and alter
the conditions in the internal environment. This in turn inhibits enzyme functioning
and prevents cells from undergoing normal metabolic activity.
• Examples are:
■ the build-up of nitrogenous wastes such as ammonia, which causes an increase in pH in
cells, resulting in them becoming more alkaline, affecting enzyme activity
■ carbon dioxide accumulation, which lowers pH, resulting in the internal environment
becoming more acidic. These changes to the acidity or alkalinity of cells slow down or inhibit
enzyme functioning in metabolism. The accumulation of wastes that do not alter the pH
may cause other problems—increased solute concentrations interfere with reaction rates
and an osmotic imbalance adversely affects membrane functioning.
• Urea - not as toxic as ammonia but can soon build up to toxic levels in the blood, poisoning
the cells and retarding metabolism
Identify the role of the kidney in the excretory system of fish and mammals
•
•
primary role osmoregulation. This is the regulation of salt and water levels in the body
The Kidney controls water balance, eliminate nitrogenous wastes, osmoregulation; regulate
salt & water concentration and stabilises the internal environment by filtering the blood and
reabsorbing required nutrients.
The fish kidney
• primary role of kidneys is osmoregulation—the regulation of the water and salt
concentrations in the body.
• In fish, excretion of nitrogenous waste products occurs across the gills. The kidneys adjust
the levels of water and mineral ions in the fish’s body in order to maintain a constant
concentration of internal fluid for the cells
Freshwater fish
• Bony fish living in fresh water maintain a higher concentration of solutes in their body than
the concentration in the water outside (that is, they are hypertonic to their surroundings).
• Water therefore tends to diff use into the body and so the fish need to continually get rid of
the excess.
• Their kidneys produce copious amounts of very dilute urine in an almost continuous stream
in order to achieve this.
• As fresh water has a lower concentration of ions than the fish do, the kidneys actively
reabsorb salts to prevent their loss.
Saltwater fish
• Their internal body fluids are less concentrated than the surrounding water.
• To avoid water loss from their body, marine fish keep drinking salt water.
• They absorb the water and salts.
• The water is retained and the salts actively excreted, some via the gills and some via the
kidneys.
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• Saltwater bony fish excrete very little urine.
The mammalian kidney
• regulate the internal salt and water concentrations of the body, and excrete urea, the
nitrogenous waste produced by mammals.
• Mammals’ urine contains urea as well as water and salts. The kidneys ensure that the
concentration of blood and interstitial fluid is constant
Deamination
• Proteins are made from amino acids.
• made, used and broken down in cell metabolism.
• Mammals unable to store amino acids, so any excess becomes nitrogenous waste to be
removed.
• These excess amino acids are transported to the liver, where they are broken down in a
process called deamination.
• This involves removing the part containing nitrogen to form urea.
• The remainder is converted to a carbohydrate which may be stored (as glycogen) or used
immediately.
• Urea is transported by the blood to the kidneys and excreted in the urine.
• The kidneys of mammals regulate the internal salt and water concentrations of the body,
and excrete urea.
Explain why the processes of diffusion and osmosis are inadequate in removing dissolved
nitrogenous wastes inn some organisms
Diffusion and osmosis require no energy input from cells and as a result they are slow processes.
Diffusion requires there to be a difference in concentrations for it to take place. Therefore when the
concentration of nitrogenous wastes within blood and urine are equalised, then no further waste
would be removed from the blood. Active transport is therefore essential at this point to remove
wastes from the blood
Diffusion is non selective (random movement of molecules). It is passive (will not work against a
concentration gradient).
Osmosis is the movement of water only. Passive (will not work against a concentration gradient). It is
the random movement of molecules.
Distinguish between active and passive transport and relate these to processes occurring in the
mammalian kidney
Passive transport includes the process of diffusion and osmosis. These types of movement require
no energy input from the cell because the molecules are moving along a concentration gradient
from a region of high concentration to a region of low concentration. Example of passive transport in
the mammalian kidney include:
The excretion of excess water by osmosis
•
The excretion of nitrogenous wastes such as urea and ammonia by diffusion when the
•
concentration in the blood is higher than it is in the urine.
Active transport requires the input of cellular energy to actively move molecules against a
concentration gradient. This means that molecule can move from an area of low concentration to an
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area of high concentration. Active transport mainly moves sodium ions, glucose, amino acids and
hydrogen ions across the wall of the nephron. For example
All glucose and amino acids are reabsorbed by the kidney so that they are not lost in the
•
urine
Additional nitrogenous wastes and hydrogen ions are removed from the capillaries in the
•
kidney and added to urine
Salts are actively transported from the urine back into the kidney cells.
•
o
Removing salts from the urine and increasing their concentration in the bloodstream
causes water to follow, but the movement of water is a passive form of transport
•
Reabsorption: The substances the body can reuse are reabsorbed into the capillaries
surrounding the nephron. Eg, vitamins and hormones. This is active transport and requires
energy. Some other substances passively re-enter the blood. Eg, water and salts. This occurs in
the proximal and distal tubules and in the loop of Henle.
•
Secretion: This is the process where the body actively transports substances from the blood
into the nephron. This is active transport.
Explain how the processes of filtration and reabsorption in the mammalian nephron regulate body
fluid composition
The main processes that regulate body fluid composition and produce urine are filtrations and
reabsorption.
Filtration:
• The renal artery that enters the kidney branches into numerous smaller and smaller vessels,
each terminating in a globular network of capillaries - the glomerulus.
• Filtration of the blood takes place at the surface between the glomerulus and the lining of
each Bowman’s capsule.
• Substances that are small enough (water, amino acids, glucose, salts/ ions and nitrogenous
wastes) squeeze through the capillary wall and into the glomeruler filtrate of the Bowman’s
capsule.
• Filtration separates substances from the blood based on their size and does not take into
account whether they are wastes that need to be excreted or if they are nutrients that are
still required by the body.
• Therefore glomeruler filtrate is not the final product. Its composition is further adjusted as it
continues to flow along the nephron.
• The nephron is the functional unit of the kidney.
• They are found in the outer cortex & central medulla.
• Blood flows into the nephron under high pressure.
• Network of capillaries known as the glomerulus carries blood.
• The thin walls of capillaries & high pressure cause all substances to leave the blood.
• Filtration is non selective; all components are removed except erythrocytes & large proteins.
Reabsorption:
• Reabsorption of useful solutes from the glomeruler fluid takes place in the proximal
convoluted tubule, the loop of Henle and the distal convoluted tubule.
• In the proximal tubule all organic nutrients (amino acids and glucose) and some ions
(sodium, potassium, calcium) are reabsorbed.
• As the nutrients are actively reabsorbed, water follows them across by passive process of
osmosis.
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•
•
•
In the ascending loop of Henle and the distal tubule more ions are reabsorbed into the
surrounding capillaries and water by osmosis follows before the final product urine is passed
on via the collecting ducts to the ureters.
Feedback mechanisms determine the quantities of substances reabsorbed.
Substances re-enter through distal & proximal tubules, the loop of Henle & the collecting
duct. All excess nutrients & wastes removed for excretion.
Outline the role of the hormone aldosterone and ADH in the regulation of water and salt levels in
blood
What are hormones?
Hormones are chemical control substances secreted by endocrine glands directly into the blood
stream. They travel via the circulatory system, when they reach their target cells, the cells respond.
In this case the cells are the kidney nephrons.
Aldosterone - brings about salt retention
• hormone produced and released from the adrenal gland situated above the kidneys.
• The hormones stimulate the tubules to increase the active reabsorption of sodium ions
against the concentration gradients from the tubules back into the blood of the capillaries
surrounding the tubules.
• This increases the solute concentration of the blood and hence stimulates the passive
reabsorption of water via osmosis, from the tubules back into the blood. This ultimately
corrects the blood pressure.
• Release of aldosterone also stimulates the intestines to absorb more sodium ions which
cause a decrease in potassium ion concentration. The release of aldosterone increases the
blood pressure and concentration of urine
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
A decrease in the concentration of sodium ions in the bloodstream leads to a decrease in
blood volume
This stimulates the cells in the adrenal cortex (outer tissue of the adrenal glands which sit on
top of each kidney) to produce and secrete aldosterone
When aldosterone reaches the kidneys it increases the permeability of the nephron to
sodium
Reabsorption of sodium ions into the surrounding kidney tissue and capillaries occurs,
resulting in retention of salt by the body
That means that less salt is lost in urine. In the absence of aldosterone the salt concentration
in urine is higher
High Salt Levels:
High blood volume and blood pressure due to water diffusing in.
Levels of aldosterone decreased.
Less salt reabsorbed, less water diffusing in
Salt level decreased, blood volume and pressure decreases
Low Salt Levels:
Low blood volume and blood pressure due to water diffusing out.
Levels of aldosterone increased.
More salt reabsorbed, more water diffusing in
Salt levels increase, blood volume and pressure increase
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ADH (Anti-diuretic hormone) - brings about water reabsorption
When a mammal becomes dehydrated the blood volume drops, this is detected by the
•
hypothalamus
It stimulates the pituitary gland to release ADH
•
ADH increases the permeability of the distal tubules and collecting tubules in the nephron to
•
water
Water is reabsorbed from these tubules into the kidney tissue and bloodstream
•
Water is conserved within the body
•
•
High Salt Concentration:
ADH levels increased
collecting ducts and distal tubules become more permeable to water
more water reabsorbed
concentration returns to normal (Concentrated urine)
•
Low Salt Concentration:
ADH levels increased
collecting ducts and distal tubules less permeable
less water absorbed
concentration returns to stable state. (Dilute urine)
Present information to outline the general use of hormone replacement therapy in people who
cannot secrete aldosterone
•
•
•
•
•
•
•
•
•
•
•
Addison's disease a rare endocrine, or hormonal disorder that affects about 1 in 100,000
people.
The disease is characterized by weight loss, muscle weakness, fatigue, low blood pressure,
and sometimes darkening of the skin in both exposed and non-exposed parts of the body.
Addison's disease occurs when the adrenal glands do not produce enough of the hormone
cortisol and in some cases, the hormone aldosterone. For this reason, the disease is
sometimes called chronic adrenal insufficiency.
Cortisol is produced by the adrenal glands, located just above the kidneys.
It belongs to a class of hormones called glucocorticoids, which affect almost every organ and
tissue in the body.
Cortisol's most important job is to help the body respond to stress.
Among its other vital tasks, cortisol:
helps maintain blood pressure and cardiovascular function;
helps slow the immune system's inflammatory response;
helps balance the effects of insulin in breaking down sugar for energy; and
helps regulate the metabolism of proteins, carbohydrates, and fats.
Aldosterone belongs to a class of hormones called mineralocorticoids, also produced by the
adrenal glands.
It helps maintain blood pressure and water and salt balance in the body by regulating the
amount of sodium and potassium in the kidney.
When aldosterone production falls too low, the kidneys are not able to regulate salt and
water balance, causing blood volume and blood pressure to drop.
Treatment of Addison's disease involves replacing, or substituting, the hormones that the
adrenal glands are not making.
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•
•
•
Cortisol is replaced orally with hydrocortisone tablets, a synthetic glucocorticoid, taken once
or twice a day.
If aldosterone is also deficient, it is replaced with oral doses of a mineralocorticoid, called
fludrocortisone acetate (Florine), which is taken once a day.
Without the therapy there will be incorrect salt levels in the body and dangerously high
potassium levels which can cause high blood pressure, electrolytes imbalances and cardiac
failures. Hence hormone replacement therapy is of great importance
Gather, process and analyse information from secondary sources to compare the process of renal
dialysis with the function of the kidney
• People with dysfunctional kidneys are not able to remove wastes such as urea. They have to
undergo renal dialysis to regulate their blood.
• Dialysis means to separate. It simulates the role of the nephron in the kidney and separates
molecules from the blood.
• It prevents waste products of metabolism building up as high concentrations can lead to
tiredness, weakness, loss of appetite.
• It sustains the life of people with impaired kidney function.
• Renal Dialysis removes wastes in blood by diffusion across a semipermeable membrane.
• The blood is drawn out of a vein, into dialysing solution, which moves through plastic tubing
into the machine. A bundle of semipermeable fibres that allow wastes to pass out into
dialysing solution. The clean blood is then taken back into the blood stream.
• The Kidney filters the entire blood volume once every ½ an hour. It is faster & more efficient
than dialysis.
• The two forms of dialysis are:
Haemodialysis:
The blood is extracted from the body from a vein and passed into a dialyser, which is a
bundle of hollow fibres made of a partially permeable membrane
The dialyser is in a solution of dialysing fluid, which has similar ion concentrations of blood
The dialyser only allows wastes to pass through, and not blood cells and proteins. In this way
it is similar to the filtrations stage of the nephron
The wastes diffuse into the solution, and it is constantly replaced
The anti-clotting agent, heparin, is also added to prevent clotting
The blood is then returned to the body
Peritoneal Dialysis:
This occurs in the body
Dialysis solution is introduced into the peritoneal (abdominal) cavity through a catheter
The lining of the peritoneal cavity is a natural semi-permeable membrane and has its own
rich blood supply
The wastes diffuse into the solution, which is replaced.
(IN BIO PRAC BOOK)
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Analyse information from secondary sources to compare and explain the differences in urine
concentration of terrestrial mammals, marine fish and freshwater fish
Organism
Environment
Urine Concentration
Marine Fish
Internal salt concentration is lower
than surroundings, therefore;
Water moves out of the fish by
•
osmosis
• Kidneys reabsorb water, while
excreting salts
To reduce water loss
•
constantly drink saltwater and
excrete salt from gills
Produce small amounts of highly
concentrated urine
Reason: Problem of osmosis.
Concentration of ions lower in the body
than in the water. Water diffuses out, salts
diffuse in. Excess salts excreted through
gills, little urine excreted. Large amounts of
water drank to replace it.
Freshwater
Fish
Internal salt concentration is higher
than surroundings, therefore;
Water moves into fish by
•
osmosis while diffusing out salt
Kidneys absorb salts from
•
surrounding water through gills
• Removes excess water. They
also rarely drink water
Excrete large amounts of dilute urine
Reason: Concentration of dissolved ions
higher in the body, water diffuses in. Must
remove excess water through large
quantities of dilute urine.
Terrestrial
Mammals
Variable conditions. Kidneys must
respond to changes in environment;
Water loss through lungs and
•
skin
Gain water by drinking water
•
and food
• Regulates concentration of
blood, while at the same time
excretes urea and conserves
water.
Mammals, generally excrete urine that is
more concentrated than body fluids to
reduce water loss. Concentration changes
with the availability of water, as well as
temperature and water loss through
sweat. Water levels in blood rise, urine
amount rises, and concentration decreases
and vice versa.
Reason: Problem of conserving water while
removing nitrogenous waste.
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Use available evidence to explain the relationship between the conservation of water and the
production and excretion of concentrated nitrogenous wastes in a range of Australian insects and
terrestrial mammals
Ammonia:
• Highly toxic.
o Removed immediately.
• Product of most aquatic animals.
• Immediate product produced from the breakdown of amino acids.
• Highly soluble in water.
o Requires large quantities of water to be safely removed.
Urea:
• 10,000 times less toxic than ammonia.
• Can be stored in body fluid for a limited time.
• Produced by mammals, sharks, amphibians.
• Highly soluble in water.
o Small amounts of water required to remove it.
Produced
from the breakdown of amino acids.
•
• Major source of water loss in mammals.
Uric Acid:
• < toxic than urea & ammonia.
• Stored in the body for extended time.
• Product of terrestrial animals.
o Birds, reptiles, insects.
• Highly insoluble in water.
o Minimal water required to remove it.
Spinifex hopping
mouse
Terrestrial
Urine in concentrated form. Arid environment. Drinks little H2O.
Wallaroo
Terrestrial
Concentrated urine. Efficient excretory system. Recycles N & urea to
make concentrated urea. Survives in an arid environment.
Insects
Terrestrial
Uric acid. Insects covered in a cuticle impervious to H2O. Conserve
H2O by producing a dry paste of uric acid.
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Type of nitrogenous
waste and
conservation of
water
Australian Insects
Insect 1
Grasshopper
Insect 2
Aquatic insect
Mammal 1
human
Mammal 2
Kangaroo
Low
High
Low
Low
Availability of water
in the environment
• Nitrogenous waste •
• Toxicity
•
Energy
required
for
•
•
production
•
•
Amount of water
lost through
excretion
Dilute/ concentra
ted urine and
explanation why
Identify organs of
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Australian
Terrestrial
Mammals
uric acid
Low toxicity
Large energy
required
•
Ammonia
•
Urea
•
High
•
•
No energy
Toxic, but
ammonia so
10 000
can be stored
times less
in the body
toxic than
for longer
ammonia, • More energy
so it can
to produce
be safely
than
stored in
ammonia,
the body
less than uric
for a
acid
limited
time
•
More
energy to
produce
than
ammonia,
less than
uric acid
•
Minimal
•
Large
amounts
•
Concentrated
•
Dilute (has to
be due to the
toxicity of
ammonia)
•
Malphigian
•
Malphigian
• Minimal
• Concentrated
• Urea
• Not as toxic as
• Minimal
• Concentrated
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urine and dry
faeces to
conserve
water as
water
availability is
often low
•
Liver-
Page 41 of 51
•
Kidney’s-
excretion and outline
their functioning
•
tubules:
increases the
surface area for
the transport of
wastes into the
digestive/ excret
ory tracts
Rectumtransports most
solutes back
into the blood,
followed by
water
•
tubules:
increases the
surface area
for the
transport of
wastes
Rectumtransports
most solutes
back into the
blood,
followed by
water
•
multipurp
ose organ
which
include
functions
of 1)
making
bile, 2)
detoxifies
blood, 3)
destroys
red blood
cells, 4)
makes
urea from
excess
amino
acids.
Kidney’smaintain
the
balance
of salts
and
water in
the body
and so
has a vital
role in
homeost
asis
2. Ureter
carries urine to
bladder
3. Urinary
Bladder stores
urine
4. Urethra
carries urine
outside the body
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•
•
maintain
the balance
of salts and
water in
the body
and so has
a vital role
in
homeostasi
s
Bladdercollects
urine
excreted
by the
kidney
before
disposal by
urination
Urethratube that
carries
fluids
(urine) out
of the body
Background information
•
•
•
•
All animals must eliminate nitrogen-containing metabolic wastes that arise from the
breakdown of protein so that they do not accumulate in toxic amounts.
Excess amino acids (and nucleic acids) in the bodies of vertebrates are de-aminated and the
nitrogen-containing amino group is removed and combined with carbon dioxide to produce
ammonia.
The ammonia is still fairly toxic and so it must be excreted directly, diluted with large
quantities of water, or it may be changed to a less toxic form of nitrogenous waste. (Just as
carbon dioxide changes the pH of solutions to become more acidic, so ammonia makes the
pH more alkaline—thus changing the internal environment from its optimal range and
affecting enzyme functioning and metabolism.)
Urea and uric acid are less toxic forms of nitrogenous wastes which can be excreted in a less
dilute form. The formation of all nitrogenous wastes occurs in the liver and they are then
carried to the kidneys for excretion.
Nitrogenous wastes and water conservation
•
•
•
•
•
•
•
•
•
The environment in which an organism lives determines how important the conservation of
water is for the survival of that organism.
In environments where water is scarce, for example some arid terrestrial habitats, natural
selection has favoured the survival of those organisms that secrete less toxic forms of
nitrogenous wastes, because they are able to conserve more water while still flushing out
their wastes.
Ammonia is very toxic compared with other nitrogenous wastes. It requires no energy to be
made, but must be excreted immediately and in a dilute form with a great deal of water.
It is therefore most commonly secreted by aquatic invertebrates and fish that live in fresh
water, where the availability of water is not a limiting factor.
Urea is the most common form of nitrogenous waste excreted by terrestrial mammals, adult
amphibians and some fish.
It is not as toxic as ammonia and so it can be excreted in a less dilute form, resulting in less
water loss. It does, however, require more energy for its production.
Uric acid is the least toxic form of nitrogenous waste and so it is excreted (as a semi-solid,
whitish paste) by animals that have a particular need to conserve as much water as possible,
for example birds and most invertebrates, including insects.
The synthesis of uric acid uses a large amount of energy in contrast to ammonia and urea,
although it has the smallest amount of water loss in the process of excretion.
The excretion of uric acid, which is not very soluble in water, allows animals such as insects
to conserve water within the body, as its low toxicity means it can be excreted with minimal
water loss.
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Excretion of nitrogenous wastes in insects
•
•
•
•
•
•
•
•
Insects have blind-ending kidney tubules (Malpighian tubules) that open directly into the
hind part of the digestive tract
Water and waste solutes are drawn into the blind end from the fluid in the body cavity of
the insect.
The open end of each kidney tubule empties into the hindgut of the digestive tract.
In some insects (e.g. the blowfl y) the blind-ending kidney tubules lie close to the end of
their digestive tracts and the solutes in the tubules draw water by osmosis across the
epithelium (lining) of the rectum, in this way modifying their excretory fluid so that most
water is reabsorbed from their rectal contents into the body.
As a result, they produce very dry faeces (which contain nitrogenous wastes as well as
undigested food).
Some insects such as the desert silverfish and the larval forms (meal worms) of a particular
moth (Tenebrio molitor) are able to absorb water vapour from the air through the mouth or
anus.
Water that enters the anus of the meal worm is absorbed through the rectum and is then
drawn into the adjacent kidney tubules by osmosis.
These are simple forms of tubular reabsorption, more primitive versions of that in mammals
that need to conserve water.
Conclusion
•
•
The challenge of regulating water content during excretion is therefore solved by varying the
type of nitrogenous waste excreted, which in turn determines whether urine needs to be
dilute (to safely flush out more toxic forms of waste), or if it can be more concentrated (to
flush out less toxic forms).
This affects the physiology of the animal: the amount of water that must be reabsorbed into
the body or the amount that can be lost in urine depends on the type of nitrogenous waste
excreted, as well as the concentration of salts that are being excreted. All of these factors
contribute to determining the eventual concentration of urine that is excreted.
Process and analyse information from secondary sources and use available evidence to discuss
processes used by different plants for salt regulation in saline environments
Grey Mangroves:
- Salt Exclusion: Special glands in the mangroves can actively exclude the salt from the water,
so that the water absorbed has a lower salt concentration than the water in the
environment.
- Salt Accumulation: Salt is accumulated in old leaves that drop off, so that thesalt is out of the
plant’s system
- Salt Excretion: Salt can be excreted from the underside of the leaves of the mangrove plants.
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Halophytes:
•
Plants adapted to live in a salty environment.
- Able to tolerate higher levels of salt than other organisms.
- Have mechanisms to control the levels of salt.
Mechanisms:
•
•
•
Salt barriers.
- Tissues in roots & lower stems stop salt from entering the plant, but
allow water to enter.
Secretion.
- Able to concentrate salt & secrete it through glands on the leaves;
where it is washed off.
Salt deposits.
- Salt deposited in old tissue which is disregarded.
Eg.
- Grey mangrove secretes salt.
- Salt marsh plants use salt deposits.
Salt regulation in plants in saline environments
Background information
•
•
•
•
•
Salt, even in relatively small concentrations in soil water, has a damaging effect on cell
ultrastructure and cellular metabolism.
Plants that are adapted to saline environments are called halophytes.
The plants use either salt tolerance (salt accumulation) or salt avoidance (salt exclusion) as
strategies to survive in environments where they are exposed to high salt concentrations.
Salt tolerant plants (e.g. sea grass and mangroves) are able to maintain metabolic
functioning even though their cells accumulate sodium and chloride ions. They minimise salt
toxicity by increasing their water content in large vacuoles.
Salt avoidant plants (salt excluders) minimise the salt concentrations of cells through
structural and physiological adaptations such as stopping salt from entering at the roots.
Examples of halophytes
•
•
•
•
Saltbush (Atriplex vesicaria) is an excluder—
Actively transports excess sodium and chloride ions into bladder cells situated on the tip of
hairs on the surface of leaves
When the bladder cell reaches capacity it bursts, releasing the salts into the environment.
Palmer’s grass (Distichlis palmeri) also actively secretes salts from specialised cells to avoid
high salt concentration within the cells.
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•
•
Succulents minimise the salt toxicity through increasing water content in large vacuoles,
where the accumulation of excess salt is balanced with additional water drawn into the cells.
Pickleweed (Salicornia) uses this method and also actively transports salts from the
cytoplasm by a sodium—potassium pump on the vacuole membrane.
Pigface (Carpobrotus glaucescens), a succulent that grows on coastal sand dunes, tolerates
salt by increasing water uptake to dilute the salt. It also stores excess salt in a location away
from sensitive cells.
Define enantiostasis as the maintenance of metabolic and physiological functions in response to
variations in the environment and discuss its importance to estuarine organisms in maintaining
appropriate salt concentrations.
• Some organisms live in environments where they experience extreme fluctuations in
conditions.
• To survive, these plants and animals have evolved adaptations that allow them to cope
physiologically with these fluctuations, a survival mechanism called enantiostasis.
• Enantiostasis is the maintenance of metabolic and physiological functions in response to
variations in the environment.
• The survival of species that live in an environment such as an estuary, where salt and water
concentrations fluctuate broadly on a daily basis, depends on their ability to either avoid
these changes or to tolerate them.
• Organisms that move freely between the sea and rivers experience similar fluctuations in
environmental conditions, and they too have developed mechanisms of avoidance or
tolerance.
• Enantiostasis is not limited to fluctuations in salt levels. For example, extreme changes in
environmental pressure are experienced by diving birds and so these animals must also rely
on enantiostasis for their survival.
Estuarine organisms— maintaining a water and salt balance
In estuaries, where a river meets the sea, and freshwater mixed with saltwater, the daily change in
tides affects the salinity of the environment in the following ways:
■ At high tide, sea water flows into the river mouth, creating an environment with a higher salt
concentration (a higher osmotic pressure) than the cytoplasm of cells and body fluids in organisms.
This salt water has the tendency to draw water out of cells by osmosis.
■ At low tide, sea water flows out of the river mouth and fresh water flows into the estuary. Plants
and animals in the estuary which are subjected to this predominantly fresh water environment with
a high water potential face the challenge of water tending to move into living tissue.
Osmoregulation in organisms inhabiting an estuary is a challenge— they need to maintain normal
metabolic functioning, despite these enormous fl uctuations within the environment.
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Living organisms employ one of two strategies in enantiostasis:
1.Osmoconformers
• Organisms that allow their body’s osmotic pressure to vary with the environment.
• Don’t maintain homeostasis.
• Concentrations of internal fluids remain isotonic to external fluids.
• Vary the concentration of solutes within cells to maintain functioning.
• are organisms that tolerate the changes in the environment by altering the concentration of
their internal solutes to match the external environment (their body fluids ‘conform’ to that
of the environment).
• Their metabolism is able to tolerate changes in salinity in their own body fluids and cells.
• Eg. Sharks are osmoconformers. They are euryhaline; meaning they can tolerate changes in
salt concentration.
2. Osmoregulators
• Maintain homeostasis regardless of the concentration of the external environment.
• are organisms that avoid changes in their internal environment and have the ability to keep
the solutes at an optimal level (‘regulate’ solute concentrations within the body), regardless
of the differing external environment.
• These organisms are unable to tolerate a range of salt concentrations in their body fluids
and cells and so they have mechanisms to exclude salt to keep the internal fluid
concentration constant, despite fluctuations in the environment.
• Eg. Freshwater & marine fish regulate their internal environment to maintain homeostasis
• However, as the salt concentration of body fluids in an osmoconformer changes, various
body functions are affected, such as the activity of enzymes. For normal functioning to be
maintained, another body function must be changed in a way that compensates for the
change in enzyme activity.
•
One example of enantiostasis is when a change in salt concentration in the body fluid, which
reduces the efficiency of an enzyme, is compensated for by a change in pH, which increases
the efficiency of the same enzyme.
Describe adaptations of a range of terrestrial Australian plants that assist in minimising water loss
Problems facing plants that minimise water loss
•
•
•
•
•
main form of water loss in plants is by means of transpiration— evaporation of water from
the stomata of leaves.
Transpiration serves two main functions—it lifts water and dissolved ions up the stem to the
top of plants in a continuous transpiration stream and it is a form of evaporative cooling, a
process that is essential in regulating temperature in plants.
Those plants that live in areas where water is in limited supply must achieve a balance
between how much water the plant can afford to lose for cooling purposes and the risk of
dehydration.
Xerophytes are plants that live in arid conditions and possess adaptations that equip them
to achieve this balance and survive in their hostile environment.
Leaves of plants contain stomata and so they are the organs where most transpiration in
plants occurs.
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•
Stomata are stimulated to open in the presence of light and/ or excess heat in well hydrated
pants, leading to a loss of water by the process of transpiration.
• About 98% of water loss from plants occurs as a result of transpiration.
• The advantage of the opening of stomata is to allow evaporative cooling and to allow carbon
dioxide to enter the leaves for photosynthesis. The disadvantage is that it exposes plants to
the risk of dehydration.
• Most of Australia is hot and dry, so water (like soil nutrients) becomes a limited resource for
plants, available in short supply or only in sporadic bursts.
• Stomata close in response to darkness, dehydration and a lack of carbon dioxide.
• Three main problems face plants with regard to minimising water loss:
1. If plants lose too much water through transpiration they run the risk of dehydrating, yet loss of
water by this evaporative cooling mechanism is an essential part of temperature regulation to keep
plant cells within the optimal temperature range for metabolic functioning.
2. If plants reduce the surface area of their leaves or lose their leaves, the number of stomata
exposed to the external environment may be reduced, but the reduced exposure of photosynthetic
surface area to sunlight may be inadequate for photosynthesis to occur.
3. If plants retain their leaves, but develop ways of ensuring that stomata do not open, gaseous
exchange between the leaf and the surrounding air becomes limited and, as a result, may not allow
sufficient carbon dioxide into the plant—a necessary requirement for photosynthesis.
Adaptations in Australian plants to minimise water loss
•
•
•
•
Many plants that live in arid conditions display complex xerophytic adaptations, features
which have evolved and allow these plants to minimise water loss while maintaining
functions such as cooling of the plant and photosynthesis.
Most of these adaptations are evident as modifications of leaves, but other organs may also
show modifications.
Stems and leaf stalks (petioles) have sparsely distributed stomata, but are green and thus
have adequate photosynthetic tissue. This can be used to advantage in allowing xerophytes
with reduced leaves to carry out other essential functions to survive in their arid habitat.
Xerophytes, such as some Australian plants, live in hot, dry habitats where they are exposed
to bright sunlight. They minimise water loss in four main ways, as outlined below.
Reducing the internal temperature
•
•
Some plants have developed structural features or physiological mechanisms other than
transpiration to reduce their internal temperature, allowing the plants to use less water for
evaporative cooling, but still keep their temperature within the correct range for
metabolism.
For example, their leaves may be coated in a shiny waxy cuticle or they may have white hairs
to refl ect sunlight.
Australian examples
•
•
•
•
The saltbush has waxy leaves that reflect heat and light.
Eucalypts and banksias have coarse, leathery leaves with a thick cuticle to protect them from
the excessive sunlight by giving some insulation and reducing the small amount of
evaporation that sometimes occurs through thinner leaf cuticles.
Plants with these tough, dry leaves are known as sclerophylls (Greek: sclero—hard and
phyllo—leaf).
In addition, both of these features ensure that all the epidermal cells are waterproof,
preventing loss of water by evaporation from these surface cells to the outside.
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Reducing the exposure of transpiring plant structures to sunlight
Plant organs that have the most abundant stomata (leaves and leaf-like organs such as flower petals)
have the greatest rates of transpiration. Some plants reduce the exposure of these organs (and their
stomata) to light by:
■ changing the orientation of leaves so that stomata are not exposed to direct light (and so they do
not open)
■ reducing the surface area of organs that have the highest proportion of stomata
■ the complete loss of transpiring plant organs (for example, leaves or leaf-like parts of the plant
such as flowers). (These plants need to have some additional adaptations to prevent overheating,
increase their photosynthetic tissue or ensure pollination, as a result of their loss leaf or petal
surface area.)
Australian examples
■ Reduced leaves
•
Plants like Hakea and Acacias (wattles) also have leaves that have become reduced in size,
where each leaf is divided into pinna or leaflets.
• Some plants have their leaves reduced to tiny brown bracts or scales and their
photosynthetic function is taken over by other parts of the plant, for example cladodes
(photosynthetic stems) and phyllodes (photosynthetic leaf stalks).
• The photosynthetic stems or stalks that take over the function of the leaves have very few
stomata and therefore the amount of water lost by transpiration is reduced, while the
photosynthetic surface area is still sufficient.
• Many phyllodes and cladodes have the added features of hairs and/ or sunken stomata.
• Cladodes are common features of Australian she-oaks (casuarinas).The green, needle-like
structures that resemble leaves are in fact modified stems.
• These needles have tiny light-coloured markings at regular intervals along their length.
• Closer examination (for example, with a hand lens) reveals that these light areas are actually
rings of tiny brown scale leaves, a feature to reduce the surface area of leaves and therefore
their exposure to the sun
• Phyllodes, common to Acacia species (Australian mulga, for example Acacia Aneura), are
broad, fl at leaf-shaped leaf stalks (petioles) that take over the function of leaves. These are
common in Acacia species and the tiny, brown scale at the tip of each phyllode is all that
remains of the reduced leaf.
■ Reduced size of fl owers or having no petals can also reduce the amount of water a plant requires;
for example, the Acacia has small clustered fl owers, reducing the energy and water required to
needed to produce them. (Petals are considered to be modifi ed leaves, so reducing the size of fl
owers or loss of petals also reduces evaporation of water from their surfaces.)
■ Shedding leaves is another way of reducing the water lost by leaves, for example the river gum.
■ Orientation of leaves on the stem is another feature of plants to prevent overheating is the
orientation of leaves on the stem.
• eucalypts have an adaptation that helps them to survive—their leaves hang in a vertical
position to reduce the surface area that is exposed to the sun during the heat of the
noonday sun.
• This serves an additional function—that of minimising water loss because the stomata are
not directly exposed to sunlight during the hottest part of the day and will close.
• Eucalypts therefore regulate the times of stomatal opening and closing— during the cooler
early morning and late afternoon, stomata are open for photosynthesis, but when the
temperatures increase to a level that causes water stress to the plant the Stomata then
close.
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Reducing the difference in water concentration between the plant and the outside air
•
•
•
•
The difference in water concentration (or water potential) between the plant and the
surrounding atmosphere determines how much water is lost by transpiration.
On a hot, dry day, the water concentration in the air is much lower than that in the internal
tissues of the leaf and so more water is lost by transpiration than on a cooler or more humid
day.
Since plants cannot change the overall external environment, many have adaptations that
allow them to create their own smaller ‘microclimate’ in the air immediately surrounding
each leaf.
Structures such as hairy leaves or rolled leaves trap water in the immediate vicinity and in
this way they keep air around the plant humid by preventing the moist air being swept away
by dry air currents and they also create a barrier to evaporation.
Australian examples
•
•
•
•
•
Sunken stomata or stomatal pits occur in Hakea and in the cladodes of sheoaks.
The actual stoma (breathing pores) are lower than the main surface of the leaf and this
allows moist air to be trapped in the pit, therefore reducing the difference in water potential
immediately outside the stoma (in the pit) and inside the leaf.
Epidermal hairs trap a moist layer of air, resulting in a smaller difference between the
concentration of water in the leaf tissue and the water vapour in the layer of air trapped by
the hairs—for example, hairs on the under-surface of leaves of the coastal banksia.
Curled or rolled leaves, such as those of porcupine grass (Miscanthus sinensis), enclose a
microclimate of humid air to reduce the difference in water potential (see Fig. 3.16b).
These adaptations allow plants to keep their stomata open for a longer period of time, as
there is not as much water being lost and so gaseous exchange for photosynthesis can occur
freely.
Water storage
•
•
•
•
Some plants, called succulents, have adaptations such as fleshy stems or leaves which are
able to swell up and retain moisture when it is available; they then survive by using this
moisture during dry periods.
Australia has some succulent species, including the desert plant Calandrinia (parakeelya), an
important food for Aboriginal people (the leaves provide an excellent source of moisture in
desert environments and were eaten as a green salad leaf).
Fruits are structures that are removed from plants so that the seeds that they contain can be
dispersed.
Many Australian plants produce woody fruits rather than fleshy fruits, as this reduces the
amount of water lost from the plant when the fruits fall off.
The adaptations aim to:
- Increase water taken in by the roots.
- Decrease water lost through evaporation.
- Extensive underground root systems
- Close stomata when temperature reaches a certain threshold
- Hard leaves with a thick waxy cuticle
- Shiny leaves to reflect sunlight
- Hairy leaves to reduce evaporation
- Small leaves or false, photosynthesising leaves
- Thick bark
- Reduces airflow over the surface, decreasing evaporation
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- Reduced leaves & branchlets, false leaves performing photosynthesis
- Extra thickening of cell walls throughout branches
- Prevents wilting even when large quantities of water are lost
Adaptations of Australian xerophyte (plants adapted to dry conditions) include;
Hard leathery, needle-shaped leaves with reduced surface areas such as in Hakea sericea
•
(needlebush) and costal tea trees
Use of phyllodes for photosynthesis rather than leaves that would lose water by
•
transpiration, as in many acacias
Some salt bushes e.g. Atriplex, change the reflectiveness of their leaves during leaf
•
development so that they have highly reflective leaves during summer
Eucalypts avoid high radiation in the middle of the day by hanging their leaves vertically to
•
present less surface area to sun
Heat loss is greater for small leaves or highly dissected leaves than it is for larger leaves and
•
many Acacias have fronds of bipinnate leaves
Waxy cuticle prevents evaporation in many Eucalypts
•
Perform a first-hand investigation to gather information about structures in plants that assist in
the conservation of water
Aim: to gather information from plant specimens about structures that assist in the conservation of
water
Method
1.
Gather different species of australian terrestrial plants
2.
Using a disecting microscope or hand lense, observe the presence of scale leaves
3.
Using a compound microscope, observe the positin of stomata in the cross section of a leaf
Results:
Characteristic
How it reduces water loss
Plant
example
Waxy cuticle
Acts as a waterproof seal over the surface of the leaf to prevent
evaporation from the epidermal cells
Banksia
Reduced leaves
(scales)
Tiny leaves have a smaller surface area: volume ratio and fewer
stomata exposed to the sun; therefore less water is lost by
evaporation
casuarina
Leaves hanging
vertically
Less surface area exposed to sun in the hottest part of the day, so
stomata only open during early morning and evening when it is
cooler, leading to less transpiration
Eucalyptus
(In bio prac)
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Biology - maintaining a balance
1. Most organisms are active within a limited temperature
range:
Identify the role of enzymes in metabolism, describe their chemical
composition and use a simple model to describe their specificity in substrates
Metabolism - all the chemical processes occurring within cells. Two types:
• synthesis of materials (anabolism- ants build up) e.g. photosynthesis
• breaking down of materials (catabolism- cats break down) e.g. respiration
Role of enzymes in metabolism:
Enzymes are biological catalysts that accelerate chemical reactions without change
in temperature. It does this by lowering activation energy needed through specificity.
They are substrate-specific, acting on only one specific substrate due to shape of
active site. Enzyme shape not altered and can be re-used.
Enzymes are central to maintaining functioning, as without them, metabolism too
slow to support life
Chemical composition of enzymes:
Protein molecules composed of long chains of amino acids folded into a specific 3dimensional globular shape. CHON(S)- carbon,
hydrogen, oxygen, nitrogen and sometimes
sulphur
Models to explain specificity:
1. Enzymes are substrate-specific
2. Substrate and enzyme bind together at the
active site = chemical reaction
The Lock and Key Model
• Substrate fits exactly into active site forming
a complex, like a key into a lock
• Assumes that the enzyme’s active site had
a rigid shape.
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The Induced Fit Model (more recent)
• Active site slightly changes its shape to accommodate the substrate perfectly
• Assumes enzymes are not rigid
Identify the pH as a way of describing the acidity of a substance
pH is a measure of hydrogen ion (H+) concentration which are released by acids,
and is therefore a way of describing acidity (greater H+, greater acidity). pH scale
runs from 0 to 14:
1) a pH of 7 is neutral - neither acidic nor alkaline.
2) a pH of less than 7 is acidic. Smaller number = more acidic
3) a pH of more than 7 is alkaline, or basic. Larger number = more
alkaline
Explain why the maintenance of a constant internal environment is important
for metabolic efficiency
So that enzymes can function effectively and metabolic efficiency can be maintained
Need a constant level of these variables:
• Temperature: Enzymes function within a narrow (optimum) range of
temperatures. Variations decrease enzyme activity. Too hot - enzymes
change shape and denature (active site won’t fit substrate). Too cold water in cells freeze, causing cell to rupture
• pH: Levels outside the optimum alter shape of enzyme = denature
• Concentration of metabolites (reactants e.g. oxygen): An absence of
reactants may slow down or stop chemical reactions
• Water and salt concentration (osmotic balance): all chemical reactions
take place in water, water concentration must be constant.
• An absence of toxins: CO2, heavy metals (mercury) and other wastes
may be toxic to cells, affecting enzyme activity. E.g. mercury blocking
active sites, CO2 altering pH of fluid
Describe homeostasis as the process by which organisms maintain a relatively
stable internal environment
Homeostasis is the maintenance of a relatively stable internal environment, despite
fluctuations in external environment. This is important for metabolic activity.
Organisms have feedback mechanisms to keep constant temperature and
concentration of chemical substances. These variables have an ideal value called a
set point- homeostasis does not maintain the exact set point, but keeps within
tolerance limits
Explain that homeostasis consists of two stages: Detecting changes from the
stable state & counteracting changes from the stable state
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Homeostasis consists of two stages:
•
•
Detecting Changes in conditions from stable state- receptors detect
stimuli that indicate a change in the body’s internal or external
environment.
Counteracting Changes to return conditions to stable – effector organs
carry out response
Outline the role of the nervous system in detecting and responding to
environmental changes
the major mechanism of homeostasis is called negative feedback
The role of the nervous system: rapid co-ordination of internal organ
systems during negative feedback
• The nervous system is made up of:
• the CNS (brain and spinal cord) which acts as a control centre to
coordinate responses
• the peripheral NS - the sensory and effector nerves that branch
throughout the body, acting as communication channels to and from
the CNS
• Co-ordination:
• Sensory cells called receptors detect stimuli
• A message of this info is transmitted to CNS via sensory nerves as
impulses
• Neuron nerves in CNS process and analyse message, and then
transmits a response to effector organs via motor nerves
• This counter-acts the change
The role of the nervous system in thermoregulation in mammals
•
•
Thermoreceptors in the hypothalamus of the brain, monitor the temperature of the
blood as it circulates through the brain. The hypothalamus is also the control centre
for temperature regulation and sends messages to effectors to cool the body down
and warm the body up
Warming the body– effectors conserve/generate heat
• Raised hairs on the body – by hair
erector cells creates an insulating
layer that traps heat lost from
radiation, convection and conduction
• Vasoconstriction – contracting of blood
vessels to let less blood near the skin
surface (heat is carried in blood)
• Shivering – heat is generated by rapid
small muscle movement
• Increased Metabolism – thyroid gland
increases metabolism, creating more
heat
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Cooling the body – effectors lose heat
• Vasodilatation –
expansion of the blood
vessels to let more blood
near the skin surface so
that heat can be lost
from radiation,
convection and
conduction
• Sweating –Liquid sweat
is secreted through
pores of skin. Heat is
removed as it evaporates
• Decreased Metabolism –
thyroid gland lowers
metabolism, generating
less heat
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•
•
Hair remains flatdecreases insulating
layer of hair
Resting- less heat is
made by muscles
Identify the broad range of temperatures over which life is found compared
with the narrow limits for individual species
•
•
•
•
•
•
there are organisms that are able to live in almost all temperatures on
earth, ranging from -70°C (at poles- arctic fox) to 56°C (in desertscamel)
this is broad, compared to the narrow temperature range for individual
species (only function at an optimal range of temperatures) –Called
there tolerance range
Platypus: -8°C to 34°C
Sydney blue gum: -1°C to 34°C
Coral reefs: 23°C-25°C
Life is found in a broad range of temp, but individual species only
found in a narrow temp range
Identify some responses of plants to temperature change
Plants need certain temperatures for growth and germination of seeds
Response to high temperatures:
• Wilting: Reduces SA exposed to the sun E.g. roses, hydrangeas
• Leaf Orientation: change the orientation of their leaves, so that leaves
hang down vertically. This reduces the SA exposed to the sun,
reducing heat absorption e.g. eucalypts
• Leaf fall: Drop some of their leaves during hot seasons to reduce SA.
This decreases heat absorption E.g. eucalypt
• Reseeding in response to extremes: Plants may die above ground, but
leave behind dormant seeds e.g. eucalypt releases seeds from
canopy, banksias
Response to cold conditions:
• Organic ‘Anti-Freeze’- some in arctic regions produce organic
compounds that reduce the temperature at which the cytoplasm
freezes, preventing the plant from freezing and dying e.g. Antarctic
hairgrass
• Dormancy- deciduous trees lose their leaves in winter and undergo a
period of dormancy, e.g. deciduous beech
E.G. Alpine Groundsel:
• Survives cold temperatures by being a short plant that is buried by
snow, protecting plant from extreme cold
• Stems and leaves desiccate to reduce damage to cells if water
freezes
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•
•
Has a hairy layer on leaves and stems to reduce freezing
Buds warm up quickly to grow and reproduce quickly in good condition
Ectotherm e.g. fish, amphibians, reptiles, plants
Use heat energy from environment to regulate body
temp. Body temp tends to fluctuate with ambient temp
e.g. Netted dragon (desert lizard):
 Behavioural - In low temps, it lies in the sun to
absorb heat energy.
 In high temps, it retreats to the shade of rocks or
to its burrow and reduce its activity to avoid
overheating. Hunts at night when cool
e.g. diamond-backed python
• Structural – black colouration allows it
to survive cold
e.g. thorny devil (lizard)
• Physiological - In heat, skin becomes
lighter in colour so that it can reflect
heat off itself
Endotherm e.g. mammals and birds
Use internal sources such as
metabolism to regulate body temp.
Body temp tends to remain stable.
e.g. Red Kangaroo
• Physiological- In hot
conditions, it
vasodilates - licks the
inside of its paws,
where skin is thinner,
and blood supply is
closer to surface.
Evaporation from
saliva promotes the
loss of heat from the
blood.
• Cold >> insulating
layer of fur
e.g. Fairy Penguin
Structural : feathers trap an
insulating layer of air
• In cold conditions,
feathers are lifted
away from skin,
increasing insulation
layer of air
• In hot conditions,
feathers lie flat
against skin, reducing
insulation layer of air
• Behavioural- in hot
conditions, they move
into water to cool
down. In cold
conditions, they
huddle close together
to reduce the surface
of skin exposed to
cold
Compare responses of named Australian ectothermic and endothermic
organisms to changes in the ambient temperature (environment temp) and
explain how these responses assist in temperature regulation
2. Plants and animals transport dissolved nutrients and
gases in a fluid medium:
Identify the forms in which each of the following is carried in mammalian
blood: Carbon Dioxide, Oxygen, Water, Salts, Lipids, Nitrogenous wastes,
Other products of digestion
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Substance
From
To
Form
Oxygen
Lungs
Oxyhaemoglobin
Carbon Dioxide
Body cells- waste
product of resp.
Body cells –
for resp.
Lungs
Nitrogenous
Waste
Liver and body cellsproduced from
breakdown of
proteins
Excretory
organsKidneys
Mostly as urea,
but also
ammonia, uric acid
and creatinine
Water
Digestive system
and body cells
Body cells
Water molecules
Plasma
Salts
Digestive system
and body cells
Body cells
Dissolved ions
Plasma
Lipids
Digestive system
Bloodstream
Plasma
Other products of
digestion
Digestive system
and liver
Body cells
Glycerol, fatty acids
and lipid droplets
As separate
molecules eg sugars
as glucose, proteins
as amino acids
Mainly hydrogen
carbonate ions
Explain the adaptive advantage of haemoglobin
Haemoglobin is an iron-containing protein found in RBC. Its advantages are:
• It increases the oxygen-carrying capacity of blood by 60 times.
Organisms without haemoglobin carry oxygen by blood plasma (90%
water). O2 is not very soluble in water and therefore cannot be carried
effectively dissolved in blood plasma. Organisms with haemoglobin
have a considerable advantage, as O2 is needed for respiration to
produce energy
• Its capacity to release O2 increases when CO2 is present. It is
important for haemoglobin to release O2 freely in cells where the O2
concentration is low. These cells release CO2 from resp. which lowers
the pH. Haemoglobin has a reduced affinity to O2 in lower pH levels,
so easily releases O2.
• Its ability to bind O2 increases once the first molecule binds to it,
increasing rate of oxygen take up
Compare the structure of arteries, capillaries and veins in relation to their
function
•
•
•
©
Arteries and veins carry blood long distances from one organ to
another
Capillaries form branching networks that surround all tissue cells,
bringing blood into close contact with cells for exchange
Each is structured for their purpose
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Carried
by
RBC
RBC
and
plasma
Plasma
plasma
Direction of flow
Arteries
Capillaries
Veins
Away from the heart
Small vessels that
surround all tissue cells,
bringing blood into close
contact with cells for
exchange
Towards the
heart
Oxygenated /
deoxygenated
Oxygenated (redder)
Except for the pulmonary
artery, which goes to
lungs from the heart
Structure
The walls are made up of
3 layers; endothelium as a
lining, smooth muscle to
contract the vessel, and
connective tissue to allow
for expansion.
Wall layers (particularly
smooth muscle) are
thicker and muscular than
veins to withstand
pressure
They link arteries and
veins
Depends on whether
receiving it from arteries
or veins
Walls consist only an
endothelium, one cells
think, for easy diffusion
Are microscopic vessels
Small lumen to force red
blood cells through in
single file, slowing down
their flow and increasing
their exposed SA for
gaseous exchange
Wall layers are
thinner and less
elastic than
arteries – less
pressure
More elastic to expand
when there is an
increased volume of blood
Fatty deposits on
endothelium
Valves (folds in
endothelium)
How blood
moves
Smooth muscle changes
diameter of lumen for
vasoconstriction and
vasodilatation
No
High pressure- pumped
from the heart
Deoxygenated
(darker)
Except for
pulmonary vein
which goes to
heart from lungs
The walls are
made up of 3
layers;
endothelium as
a lining, smooth
muscle to
contract the
vessel and
connective
tissue to allow
for expansion
Wider lumen for
easy blood flow
Valves (see
down)
No
Depends on whether
receiving it from arteries
or veins
Has valves and
surrounding
muscle to
prevent
backflow of
blood, as it is
under small
heart pressure
Low pressure –
muscular
movement and
valves
Analyse information from secondary sources to identify current technologies
that allow measurement of oxygen saturation and carbon dioxide
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concentrations in blood and describe and explain the conditions under which
these technologies are used
Pulse Oximeter
• Used extensively in hospitals
• Positive >>> Non-invasive (indirect)– a probe with a sensor is
attached to the patient’s finger or earlobe
• Measures oxygen saturation of blood by shining red and infrared light
through the finger. The amount of light absorbed by the probe is
determined by oxygen saturation levels of haemoglobin, hence
showing oxygen levels in the blood
• Used to quickly detect problems with oxygenation and gives indication
to the nature of breathing and circulation
• Can also continuously monitor oxygen saturation of patients under
anesthesia or with severe heart or breathing problems (e.g. after a
heart attack)
• Also measures pulse rate
Arterial Blood Gas (ABG) Analysis
• Invasive- takes blood sample from an artery – only carried out if
abnormalities are found in oximeter readings
• Oxygen levels, CO2 levels and pH (hydrogen ions) and bicarbonate
ions are measured directly in a Blood Gas Analyser machine
• It is carried out to assess respiratory diseases such as emphysema
and pneumonia, and to manage patients receiving oxygen therapy
Describe the main changes in the chemical composition of the blood as it
moves around the body and identify tissues in which these changes occur
•
The circulatory system in mammals transports substances (such as
gases, nutrients, wastes and hormones) throughout the body in the
blood
The circulation of blood into and out of the
heart
On every circuit of the body,
blood passes through the
heart twice
• body -> heart - > lungs - >
heart - > body
• The mammalian body
consists of four chambers:
the right and left atriums and the right and left ventricles.
The blood circulates through two systems:
The pulmonary system – heart to lungs to heart (CO2 and O2)
•
•
•
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•
The Systemic system – heart to body (except lungs) to heart
(nutrients, wastes, hormones)
•
Deoxygenated blood enters the heart from the body via the systemic
veins into the right atrium, which flows into right ventricle and is then
pushed out via the pulmonary arteries to the lungs.
After gaseous exchange in lungs, the now oxygenated blood returns
to the heart in the left atrium by the pulmonary vein, flows into left
ventricle and leaves by the systematic arteries to circulate the body
•
Chemical composition of blood as it moves around
the body
Increase in O2 and decrease in CO2
Tissues in which these changes
occur
Lung tissue
• External gaseous
exchange has occurred
Decrease in O2 and increase in CO2
General body tissues where cellular
respiration has occurred, brain
• Internal gaseous
exchange
Increase in digestive end products – amino acids,
glucose and fatty acids
Decrease in digestive end products and increase in
nitrogenous wastes (urea)
Small intestinal tissue
Increase in water, salts and vitamins
Large intestinal tissue
Decrease in nitrogenous wastes (urea) and excess
water and salts
Kidney tissue
• Excretory organ
Increase in hormones are secreted directly into
bloodstream
Endocrine tissue
Liver tissue
•
Centre of food
metabolism
Outline the need for oxygen in living cells and explain why removal of carbon
dioxide from cells is essential
Need for oxygen:
• Oxygen is needed for cellular respiration
• This is carried out by all cells to release energy in the form of ATP,
necessary for metabolism (e.g. growth, repair and reproduction)
Need to remove carbon dioxide:
• CO2 is a waste product and its accumulation can be toxic to cells
because it lowers the pH of cells and bloodstream
• This affects enzyme function
Analyse information from secondary sources to identify the products extracted
from donated blood and discuss the uses of these products
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Product
Use
Example
Red Blood Cells
To increase oxygen-carrying capacity of
blood
Platelets
Essential for blood clotting
Plasma
Also essential for blood clotting
Immunoglobins
Essential for fighting infections
People who have
anaemia, or who have
suffered heavy blood loss
Patients who have cancer
of the blood e.g.
leukaemia
People with clotting
disorders e.g. haemophilia
People whose immune
systems are not working
due to diseases such as
AIDS
Analyse and present information from secondary sources to report on
progress in the production of artificial blood and use available evidence to
propose reasons why such research is needed
Progress of research:
• Currently, artificial blood has been designed to carry oxygen (replacing the
function of haemoglobin in RBC)
• Oxygen carriers being developed are:
• Perflurocarbons – synthetic materials that can dissolve 50 times more oxygen
than blood plasma; they are cheap to produce and there is no risk of the
material being infected by diseases. However, there is much difficulty in
getting this to combine with blood
• Haemoglobin-based oxygen carriers – made from modifying haemoglobin
extracted from RBC. They do not require cross matching of blood. However,
they have a short circulation time
Why research is still needed:
Limitations of donated blood:
• The shelf life of donated blood, even under refrigeration, is short (35 days)
• There are not enough donations being made
• There is the risk that transmission of infectious diseases may occur
• Cross-matching of blood is required, limit of blood for some blood groups
Limitations of current artificial blood:
• Haemoglobin based products have a short circulation time of 20-30hrs in the
body
• Blood products do not mimic the bloods ability to fight disease and clot
• Perflurocarbons have difficulties in combining with other substances in the
blood stream
Advantages of artificial blood:
• Free of infectious agents
• Do not need refrigeration for storage and can be kept for 2-3 years
• Universal acceptance of all blood groups
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Describe current theories about processes responsible for the movement of
materials through plants in xylem and phloem tissue
Xylem (dead) is a continuous tube that passively transports water and dissolved
minerals from roots to leaves for photosynthesis by physical processes
Theory: The Transpiration Stream theory (cohesion-adhesion-tension):
1. Cohesion – water molecules stick together, forming a continuous stream of
water molecules from leaves to roots
2. Transpiration – water is evaporated from stomata’s in leaves, creating a pull
at the upper end of the water stream. This pulls the stream of molecules
continuously along
3. Adhesion – when the pull stops, water sticks to the sides of the xylem tube
and doesn’t fall down.
4. Tension/ capillarity – water moves up the xylem like a wire, as due to
cohesion and adhesion in a thin tube column of water does not break,
maintaining a continuous pull
Phloem actively transports products of photosynthesis (particularly sugars) to all
parts of the plant for respiration or storage in a process called translocation. It is alive
so that is can produce energy to transport flow. Transport is bidirectional.
Theory: Pressure Flow theory (source-path-sink)
• Flow is driven by an osmotic pressure gradient between source and
sink
• Source- Sugars are actively loaded into the sieve tube at leaves via
companion cells.
• This raises osmotic pressure (low WC), drawing water into phloem
passively from surrounding cells through osmosis
• Path- The pressure created by the water causes materials to actively
flow to the sink. Water can move into phloem by osmosis at any point
and sugar can continue to be actively loaded
• Sink - sugars are actively removed from the phloem, drawing water
with them so the flow mechanism can continue. This results in a low
osmotic pressure (high WC) at sink.
3. Plants and animals regulate the concentration of gases,
water and waste products of metabolism in cells and in
interstitial fluid:
Explain why the concentration of water in cells should be maintained within a
narrow range for optimal function
Water:
• Determines pH–Too little water leads to increase in solute concentrations
such as CO2, which lowers pH, affecting enzyme function and metabolism
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•
•
•
•
Provides structural support in cells – correct water concentrations maintain
the osmotic pressure of cells, which is responsible for structural support, esp.
in plants.
Provides medium for metabolic reactions– chemical reactions in cells proceed
only if the reactants are dissolved in water. Too much water may dilute
reactants and too little may stop reactants from dissolving in water
Too much water in cells- may cause cell to ‘burst’
Too little water- may cause the cell to dehydrate and shrink
Explain why the removal of wastes is essential for continued metabolic activity
Accumulation of wastes can be toxic to cells, as they alter the conditions of the
internal environment such as pH, affecting enzyme functioning and metabolism. E.g.
CO2 lowers pH. Nitrogenous wastes increase pH.
The excretory system is responsible for removing metabolic wastes.
THE KIDNEY!!! - Renal
Kidneys- the main organ of osmoregulation and the excretion of nitrogenous wastes
Osmoregulation- maintaining water and salt balance in the body
• The kidneys role in excretion is to filter the blood that enters it,
removing wastes from the bloodstream so that the can be excreted
• Filtration is carried out by millions of units called nephrons
Structure of a nephron
-
Pelvis : collects urine from medulla
• Cortex: the outer zone of the
kidney where filtration occurs
• Medulla: the inner zone of the kidney. Also where filtration occurs.
• Ureter: tube that takes urine from kidney to bladder
• Renal Artery: takes blood into the kidney to be filtered.
• Renal Vein takes filtered blood out of the kidney back into the circulatory
system.
• Bladder: stores urine to be excreted
Kidney Path: oxygenated blood arrives at kidney through the renal artery. It is filtered
to form urine. The kidney is drained of its fluid via two vessels:
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1. The renal vein- takes filtered blood out of the kidney back into the circulatory
system.
2. The ureter- tube that takes urine from kidney to bladder
The kidneys role in osmoregulation: control the amount of water lost in urine,
depending on the environment in which the organism lives
Identify the role of the kidney in the excretory system of fish and mammals
In fish and mammals, the kidneys play a role in both excretion and osmoregulation.
Water potential- the tendency to lose water by osmosis when water concentration is
higher outside body than in
Fresh-water Fish
•
•
•
•
•
•
•
•
•
•
•
•
Marine Fish
Environment: water
is freely available
Water tends to
accumulate in
tissues as a result
of osmosis
•
•
•
•
•
Risk of having too
much water.
Therefore:
Urinate
REGULARLY
Conserve salt
Excrete excess
water
DILUTE URINE
Excrete
nitrogenous wastes
(as ammonia- very
toxic)
◦
Kidneys are
structurally suited
to this role by
having a large
glomeruli for the
filtration of blood in
large volumes
Kidneys are not
involved in salt
balance- any
excess salt is
removed via gills
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•
•
•
•
•
•
•
Mammals
Environment: salty
Tend to lose water
by osmosis into
salty surroundings
Excess salts tend
to accumulate, by
diffusion
Risk of having too
much salt.
Therefore:
Urinate LESS
Conserve water
Excrete excess
salts
CONCENTRATED
URINE
Excrete
nitrogenous wastes
(as urea- less toxic)
◦
Kidneys have a
small glomeruli for
the filtration of
blood in small
volumes
Have mechanisms
for excreting
excess salt
•
•
•
•
•
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Environ
ment:
varies
Tend to
lose
water as
sweat in
hot
weather,
but not
as much
in cold
weather
Conseq
uently,
kidneys
have a
complex
control
mechani
sm to
ensure a
balance
between
amounts
of sweat
and
urine
excreted
URINE
VARIES
IN
CONCE
NTRATI
ON AND
VOLUM
E,
dependi
•
•
•
ng on
the need
to
conserv
e or
excrete
water
In hot
weather
(such as
desert
mammal
s) water
must be
conserv
ed.
Therefor
e less
urine,
more
concentr
ated
In cold
weather
water
must be
excreted
.
Therefor
e more
urine,
more
dilute
Excrete
nitrogen
ous
wastes
(as
urealess
toxic)
Compare and explain the differences in urine concentration of terrestrial
mammals, marine fish and freshwater fish
Animal
Urine Concentration
Reason For Difference
Terrestrial
animal
Concentration and volume varies
• In hot weather (such
as desert mammals),
less urine, more
concentrated
• In cold weather, more
urine, more dilute
Environment: varies
• Tend to lose water as sweat
in hot weather, but not as
much in cold weather
• In hot weather (such as
desert mammals) water must
be conserved. Therefore less
urine, more concentrated
• In cold weather water must
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be excreted. Therefore more
urine, more dilute
Freshwater
Fish
Marine Fish
Large quantities of very dilute urinesmall amounts of salts and large
amounts of water.
•
Small quantities of highly
concentrated urine.
•
•
•
•
Environment: water is freely
available
Water tends to accumulate in
tissues as a result of osmosis
Environment: salty
Tend to lose water by
osmosis into salty
surroundings
Excess salts tend to
accumulate, by diffusion
Explain why the processes of diffusion and osmosis are inadequate in
removing dissolved nitrogenous wastes in some organisms
Diffusion and osmosis rely on differences in concentration gradient (high to low)
between two solutions and so both stop once the concentration gradient reaches
equilibrium. No energy.
Problems with diffusion:
• Rate of movement is too slow - toxic nitrogenous wastes accumulate,
changing pH of cells
• Not all wastes can be removed - diffusion only moves substances from a
high to a low concentration and so it stop once the concentration gradient
reaches equilibrium, allowing for the accumulation of wastes, changing pH.
• Active transport is required to move wastes against concentration gradient
Problems with Osmosis:
• Too much water lost in urine- water will be drawn into urine by
osmosis to dilute wastes and equalize the concentration of the urine
and surrounding kidney tissue, causing major water loss
• Too little water loss- organisms that live in freshwater tend to
accumulate water in their bodies by osmosis. Whilst this dilutes
wastes, it does not assist the organism to excrete wastes, due to the
equilibrium of concentration gradients
Goodness of combined active transport and osmosis:
• Active transport (energy) is quicker and more effective than diffusion,
as it moves wastes even against a concentration gradient and kidney
can actively reabsorb useful materials such as salts, drawing water
with it by osmosis, to ensure that the water balance is not upset
Distinguish between active and passive transport and relate these to
processes occurring in the mammalian kidney
•
Passive transport requires no energy input from a cell, as molecules
move from a high to low concentration along a concentration gradient.
Includes diffusion and osmosis:
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•
•
•
Diffusion is the movement of any molecules from a H to a L
concentration
Osmosis is the movement of water molecules from a H to a L
concentration
Active transport requires an energy input from a cell, as molecules
move from a L to a H concentration, against the concentration gradient
Kidney:
•
•
•
•
•
•
In the kidney, substances move between the bloodstream and
excretory fluid in the nephrons by both active and passive transport
In nephrons there is a two-way movement of substances:
Waste substances pass from bloodstream into nephrons to be
excreted in urine
Substances required by the body are removed from urine in nephrons
before excretion and returned to the bloodstream
Passive transport moves water by osmosis and nitrogenous wastes by
diffusion in kidneys
Active transport moves salts, glucose, amino acids and hydrogen ions
into nephron. Additional nitrogenous wastes and hydrogen ions are
actively added to urine
Explain how the processes of filtration and re-absorption in the mammalian
nephron regulate body fluid composition
Nephron: the functional unit of the kidney. There are millions in each kidney,
responsible for filtering the blood and either re-absorbing or secreting substances as
urine for homeostasis.
A fluid travels along the nephron, with various substances added or removed to
produce the end product- urine.
The three main processes that lead to urine formation in nephron are:
1. filtration
2. reabsorption
3. secretion
Filtration
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Glomerulus – small bundle of capillaries surrounded by the Bowman’s capsule in
the kidney
Bowman’s capsule – a double-wall capsule surrounding the glomerulus of a
nephron
•
•
•
•
•
•
Filtration takes place at the surface between the glomerulus and the
Bowman’s capsule
Blood pressure forces substances within the blood that are small
enough through the walls of the glomeruli capillaries into the
Bowman’s capsule
Includes large volumes of water carrying dissolved substances such
as amino acids, glucose, salts, nitrogenous wastes and other toxic
molecules
Blood cells and proteins remain in blood
The process of filtration separates substances from the blood based
on their size, not whether they are nutrients that are still required in
the body.
This fluid in the nephron now is called glomerular filtrate
Reabsorption
As glomerular filtrate contains molecules that the body needs, certain solutes are
selectively reabsorbed into blood capillaries at various points along the nephron.
NOTE: amount of water and ions reabsorbed according to body needs
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Proximal Tubule:
All organic nutrients (amino acids and glucose), some vitamins and
some water and ions (such as sodium) are reabsorbed
Move by diffusion until concentrations are equal. Then active transport
Loop of Henle:
In descending limb, walls are permeable to water = water is
reabsorbed by osmosis
In ascending limb, walls are permeable to salts = large numbers of
sodium ions are actively reabsorbed- but no water reabsorption
Distal tubule:
Selective reabsorption of sodium ions by active transport, according to
body needs
Collecting duct:
This is the end of the nephron, and connects to the ureters
The walls are permeable to water only, and water is reabsorbed by
osmosis according to body needs
The final filtrate is called urine. It has a high concentration of urea.
Water: is reabsorbed in all parts of nephron, except ascending loop of
henle. Most water moves by osmosis, however active transport may
also be involved when forming fluid is very concentrated
Urea is not reabsorbed, despite the difference in concentration
between the forming fluid and the blood. Energy is used to ensure that
urea does not return to the blood.
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Secretion
•
•
•
the active secretion of toxic substances from capillaries into the
nephron
Proximal tubule: Hydrogen ions and drugs (aspirin and penicillin) are
secreted by active transport
Descending loop of henle: urea is secreted mainly by diffusion
Outline the role of the hormones, aldosterone and ADH (anti-diuretic hormone)
in the regulation of water and salt levels in the blood
Hormones: chemical control substances secreted by endocrine glands directly into
the bloodstream
The hormones aldosterone and ADH:
• change the permeability of membranes of cells in the nephron
• maintains homeostasis by regulating the amount of salt and water
reabsorbed
Aldosterone:
• secreted by adrenal gland
• Conserves salts by increasing the permeability of the nephron to
sodium, allowing salts to be reabsorbed
• Urine = dilute
ADH:
•
•
•
Secreted by pituitary gland
Conserves water by increasing the permeability of the nephron to
water, allowing water to be reabsorbed
Urine = concentrated
Present info to outline the general use of hormone replacement therapy in
people who cannot secrete Aldosterone
•
•
•
Used for patients suffering low levels of the hormone Aldosterone e.g.
Addison’s disease
Restores the balance of hormones, by giving patients the hormone
This increases salt conservation, raises blood pressure and reduces
danger of heart failure
Gather, process and analyse information from secondary sources to compare
the process of renal dialysis with the function of the kidney
•
•
©
If a person suffers from kidney failure, there is no natural means to
remove wastes
Renal dialysis carries out the function of failed kidneys so blood may
be filtered
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Kidney Function
Renal Dialysis
Natural body process
Artificial process to replace damaged kidneys
Performed by two fist sized organs
Performed by a large machine attached to a
computer
Performed intermittently - (2-3 times a week,
for 3-4 hours each time.)
Concentrations of blood monitored by
computers so that most wastes are removed
during treatment
Wastes removed by diffusion
Removes wastes continuously
Varies output automatically, depending on
concentrations of wastes in blood
Wastes removed by both diffusion and active
transport
Removes all wastes
Some reabsorption
Sodium, potassium and phosphate not
removed by diffusion
No reabsorption
Use available evidence to explain the relationship between the conservation of
water and the production of excretion of concentrated nitrogenous wastes in
Australian insects and mammals
Insects (grasshopper, ant)
• Need to conserve water
• Therefore excrete nitrogenous wastes in the form of uric acid (least
toxic form), which requires almost no water for excretion
Terrestrial Mammals
• Terrestrial animals excrete urea (more toxic than uric acid) which
requires more water
• To conserve water, the mammalian kidney is adapted to change the
concentration of urine, depending on the body’s needs
• Eg the red kangaroo has kidneys that produce highly concentrated
urine.
Define enantiostasis as the maintenance of metabolic and physiological
functions in response to variations in the environment and discuss its
importance to estuarine organisms in maintaining appropriate salt
concentrations
Enantiostasis is the maintenance of metabolic and physiologic functions in response
to variations in the environment. It is a survival mechanism found in many organisms
who live in environments that fluctuate e.g. estuarine organisms
Estuary – area where freshwater meets saltwater. Salinity varies considerably
depending on factors such as tides and rainfall
Organisms employ one of two strategies in Enantiostasis:
• Osmoconformers – tolerate changes by altering their internal salt
concentration to match their external environment, so that they do not lose
water and salts through diffusion and osmosis.
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•
E.g. Fiddler crabs and sharks
•
Osmoregulators –regulate internal salt concentrations despite external
fluctuations, through changing the concentration of their urine.
E.g. mussels and salmon
•
Describe adaptations of a range of terrestrial Australian plants that assist in
minimising water loss
Xerophytes are plants adapted to arid conditions. They have adaptations to conserve
water.
•
•
•
Having an extensive root system to obtain as much water
underground as possible. Eg mulga / spinifex grass
Reducing internal temperature to reduce the need for evaporative
cooling. E.g. Saltbush has waxy leaves to reflect light and heat
Reducing the exposure of transpiring structures to sunlight so water
lost through transpiration is reduced. E.g. Wattles have small leaves
with a small SA/V ratio. Eucalypts orientate leaves into vertical
position during the hottest parts of the day, reducing the SA exposed
to the sun and subsequent evaporation from leaves
Discuss processes used by different plants for salt regulation in saline
environments
In plants, salt can have a damaging effect on metabolism.
•
•
•
©
Salt excretion –Saltbush secrete salt onto leaves, which rain then
washes off
Salt exclusion – salt excluder’s prevent the entry of salt into their root
systems via the filtration system in its roots and lower stems. Eg
mangroves can exclude 95% of salt.
Salt accumulation – these minimize salt toxicity by increasing water
content in large vacuoles where salt accumulates e.g. Pickleweed
Pigface stores excess salt away from sensitive cells
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Maintaining a Balance
1. Most organisms are active in a limited temperature range
1.1 Identify the role of enzymes in metabolism, describe their chemical composition and
use a simple model to describe their specificity on substrates

Enzymes – act as biological catalysts, controlling the rate of each step of chemical
reactions

Metabolism – sum of all chemical reactions occurring in a cell

Every reaction and process (metabolism) in a cell is controlled by a specific enzyme

Chemical composition – globular proteins
Carbon, hydrogen, oxygen and nitrogen
Log chains of sequences of amino acids been forced into specific shape


Simple model
Lock-and key model – shape of enzyme and shape of active site fit together forming an
enzyme – substrate complex
Induced fit – active site slightly more flexible then keyhole, able to slightly alter shape to fit
more closely



Factor affecting enzyme activity – amount of substrate
-temperature
-pH
Process – 1. Substrate binds to active site on enzyme
2. Chemical reaction occurs, substrate bond broken
3. Product is released, enzyme returns to original form
1.2 identify data sources, plan and choose equipment or resources and perform a first –
hand investigation to test the effect of:
-Increased temperature
-Change in pH
-Change in substrate concentrations on the
activity of named enzymes
1. two water baths with one temperature 38, and the other room temperature
2. Add milk and rennin to 2 test tubes, one in each
3. 2 water baths, one pH 4, one pH 9
4. Both rennin/Milk test tubes in the 38 water bath
5. Time each mixture to estimate how long it takes to react
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Results: temp – 38 with milk, coagulated
18, no effect
pH – acidic milk coagulated
alkaline milk didn’t change
1.3 Identify the pH as a way of describing the acidity of a substance




pH is a way of describing acidity or alkalinity of a substrate.
1-6 = acidic
7 neutral
8-14 alkali/base
1.4 Explain why the maintenance of a constant internal environment is important for
optimal metabolic efficiency

Enzymes control metabolic efficiency and require specific conditions i.e. temperature and
pH level. If these levels aren’t optimum temperature, they will not work as efficiently, or not
at all. Hence, life will cease.
1.5 Describe homeostasis as the process by which organisms maintain a relatively stable
internal environment

Homeostasis = maintenance of relatively stable internal environment

Conditions controlled by homeostasis = body temperature, pH, water concentration, salt
concentration, sugar levels, levels of dissolved gases- oxygen and carbon dioxide
1.6 Explain that homeostasis consists of two stages
- Detecting changes from the stable state
- Counteracting changes from the stable state

Two stages –
Detecting change – sensory cells detect change in temp and/or chemical comp
Counteracting change – effector organs work to reverse change

Changes from stable state detected by receptors
1.7 Outline the role of the nervous system in detecting and responding to environmental
changes

Central nervous system = brain & spinal cord

Peripheral nervous system = sensory nerves and effector nerves

Stimulus response pathway: Receptor nerves detect change – sensory neuron conducts
nerve impulse to brain then nerve impulses pass info from receptor to effector neurons to
courter act change
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
Stimulus
receptor
central nervous system
effector
response

This pathway allows for the central nervous system to respond to environmental changes
1.8 gather, process and analyse information from secondary sources and use available
evidence to develop a model of a feedback mechanism
[insert diagram here]
1.9 Identify the broad range of temperatures over which life is found compared with the
narrow limits for individual species

Broad range = most organisms found between -2ᵒC and 40ᵒC however some have been
found at the poles at temperature of below - 70ᵒC and black ocean trenches above 200ᵒC

Narrow range – most individual species have a narrow limited temperature range e.g. silky
oak found in alpine regions only can withstand 0ᵒC to 38ᵒC
1.10 Compare responses of named Australian ectothermic and endothermic organisms
to changes in the ambient temperature and explain how these responses assist
temperature regulation
Endothermic = rely on internal sources such as metabolic activity
Ectothermic = heat from environment/external sources


1.11

Ectothermic –
Magnetic termites – pack walls of moulds with insulting wood pulp and
align their moulds north-south to maximise exposure o sun in morning
and evenings
Antarctic ice fish – produces anti- freeze to prevent the formation of
ice
Endothermic –
Red kangaroo – licks inside of paws where skin is thinner and blood
supply closer relying on evaporation to loose heat from blood
Bent wing bat – produces brown fat which can be quickly absorbed
during cold temperatures
Identify some responses of plants to temperature change
Vernalisation = need to be exposed to cold before can flower

After fire/heat plants may die but leave new seeds to re-sprout

Becomes much colder = beach tree, leaves drop in winter -> reduce growth, less
energy needed to avoid damage. Daffodil, plants die back leaving no parts above
ground ->protected underground to survive winter and will sprout when conditions
are favourable
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
Becomes hotter = geraniums, produces smaller leaves and reduce surface area ->
higher temp lead to increased transpiration causing plants to die out. Hakea,
extreme heat of fire causes seed dispersal -> gives seeds a chance to grow
1.12 analyse information from secondary sources to describe adaptations and responses
of Australian organisms that assist temperature regulation









Blue tongue lizard = ectothermic - bask in sun to gain heat and will hide in
burrows to preserve temperature.
Possum = endotherm –fur helps insulate in cold and possums living in Tasmania
have thicker fur for temperature adaptation
2. Plants and animals transport dissolved nutrients and gases in a fluid medium
2.1 Identify the form(s) in which each of the following is carried in mammalian blood:
Carbon dioxide
Oxygen
Water
Salts
Lipids
Nitrogenous waste
Other products of digestion
Carbon dioxide: Travels in various forms. 7% dissolved in plasma. 23% combines with
haemoglobin forming carbaminchahaemoglobin, 70% forms hydrogen carbonate ions and
travels in plasma.
Oxygen: combines with haemoglobin to form oxyhaemoglobin in red blood cells.
Water: travels in plasma
Salt: positive or negative dissolved ions in plasma
Lipids: many are water- insoluble and only travel in blood when coated with proteins
becoming lipoproteins. Travel as high or low density.
Nitrogenous wastes: ammonia which is toxic so converts to urea. Dissolved in plasma.
Other products of digestion: amino acids, glucose, vitamins etc., are generally soluble and
dissolve in plasma.
2.2
Explain the adaptive advantage of haemoglobin
Haemoglobin is a protein made up of four polypeptide chains. Oxygen is not soluble in
water, and so cannot be carried efficiently dissolved in blood plasma
Gives blood red colour and allows blood to carry oxygen
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
2.3
Adaptive advantage:
Increase the oxygen-carrying capacity of blood.

Ability to bind oxygen increases once the first oxygen molecule binds to it because
bonding to oxygen makes haemoglobin change its shape.

Capacity to release oxygen increases when carbon dioxide is present.
Compare the structure of arteries, capillaries and veins in relation to their function
Arteries - “Highway”: transport oxygenated blood (except pulmonary artery) away from
heart under high pressure.
Due to high pressure, walls must be thick, elastic to withstand pressure.
Three layers, connective tissue to allow for expansion, muscle and elastic fibres to contract
vessel and endothelium as lining
Veins – “Drain back to heart”: transport deoxygenated blood back to the heart, contains
valves to prevent back flow
Carry same quantity of blood as arteries but not as high pressure. Same layers, but not as
thick
Capillaries – “Thread through cells”: link Arteries to veins.
Walls only single cell in thickness, no elastic or muscular fibres
Site of gaseous exchange, diffusion of materials through walls to reach cells in tissues.
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2.4
Describe the main changes in the chemical composition of the blood as it moves around
the body and identify tissues in which these changes occur
Location
Lungs
Chemical
Co2
O2
Villi in small intestine
Amino acids
and glucose
Glucose
Liver
Kidneys
H2O and
nitrogenous
wastes
Glands
Hormones
2.5
Why?
 CO2 diffuses into lungs
 Decreases as diffuses out of alveoli into
lungs
 Decreases in concentration as they diffuse
from small intestines
 If there is too much glucose in the
bloodstream, it will increase. If there’s not
enough, it will increase.
 Stored as glycogen
 Kidneys can remove or allow for water to
be reabsorbed into the blood stream.
Osmoregulation maintains constant water
balance
 Concentration of urea increases in kidneys
as it’s filtered from blood and
accumulated to be excreted.
 Endocrine glands secrete hormones
directly to blood, travels till reaches target
cell/tissue
Perform a first-hand investigation to demonstrate the effect of dissolved carbon dioxide on
the pH of water
Aim: to observe the effect of pH of CO2 in water
Apparatus: straw, beaker, universal indicator paper, pH chart, water
Risk assessment: do not breathe water in
Method: 1. In a 400mL beaker, add 200mL water
2. Add pH paper, observe colour
3. Exhale through straw, into the water for 5 mins
Results: the indicator paper went more yellow to indicate a lower pH
Conclusion: a high concentration of CO2 in blood will cause the blood to become more
acidic.
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2.6
Perform a first-hand investigation using the light microscope and prepared slides to gather
information to estimate the size of red and white blood cells and drew scaled diagrams of
each.
Equipment
light microscope small transparent ruler, prepared slide
Method:
1. Set up microscope and switch on unbuilt lamp
2. Place small transparent ruler on the stage and focus using the low power
objective
3. Use the scale on the ruler to calculate the field of view using the low power
objective and use these dimensions to calculate the field of view under high
power
4. Place the prepared slide of blood on stage and focus using the low power
objective
5. Use the established size of field to calculate the size of cells
Risk assessment
Carry microscope with one hand on base and other on neck, if dropped may cause damage to
exposed feet and body
Red blood cell – no nucleus – approx. 8nm
White blood cell – nucleus – approx. 16 nm
1 cm = 10 microns
2.7
Outline the need for oxygen in living cells and explain why removal of carbon dioxide from
cells is essential
Need for oxygen :
 All living organisms use respiration to release energy to maintain life’s processes
 All organisms that aerobically respire require oxygen to survive
Glucose + oxygen
carbon dioxide + water + energy
Why carbon dioxide must be removed:
 CO2 produced as waste product.
 Accumulation of carbon dioxide causes a drop in pH, making blood acidic and impairs
metabolic reactions and action of enzymes
 Thus essential to maintain homeostasis
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2.8
Analyse information from secondary sources to identify current technology’s that allow
measurement of oxygen saturation and carbon dioxide concentrations in blood and
describe and explain the conditions under which these technologies are used
Current technology to measure oxygen saturation
Pulse oximetry – measures oxygen saturation.
 It is a non-invasive probe attached to patients finger or earlobe to monitor % of
haemoglobin saturated with oxygen
 Uses different amount of absorption of two wavelengths of light to produce graph of flow
rate
 Used in many situations, very important for measuring oxygenation and pulse rates during
operations using anaesthesia and during recovery phase
 Less accurate if patient is suffering from vasoconstriction
Current technology to measure carbon dioxide concentrations
Capnometer – incorporates infra-red detector assembly.
 Used to measure carbon dioxide and monitor air exchange in lungs of patients on
ventilators or under anaesthesia.
 Evaluates Respitory condition of spontaneously breathing patients
2.9
analyse information from secondary sources to identify the products extracted from
donated blood and discuss the uses of these products
Product extracted
Plasma proteins
From plasma or blood cells?
Plasma
Red blood cells
Platelets
Blood cells
Blood cells
Granulocytes
Blood cells
2.10




Use
Burns, volume expansion as
albumins contribute to osmotic
balance, transport lipids
Anaemia, transport oxygen
Severe bleeding. Contain
factors that control blood
clotting
Low neutrophil count. Involved
in defence against disease
Analyse and present information from secondary sources to report on progress in the
production of artificial blood and use available evidence to propose reasons why such
research is needed.
Artificial blood is ‘man-made’ products that fulfil some functions of biological blood
Reasons:
Amount of blood needed for transfusions rising each year, faster than amount being
donated
Blood bank contaminations from HIV/AIDS, hep-C, Creuzfeldt-Jakobs disease
Emergency situations, rapid need for treatment without determining blood type
Donated blood shelf life limited
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PolyHeme is a haemoglobin based oxygen therapeutic blood substitute. vt
Advantages:
 no safety concerns
 Reduce contamination risk e.g. HIV/AIDS
 Stored longer
 Immediate full capacity oxygen transport
Disadvantages:
 replaces only one function of blood, oxygen transport
Development of PolyHeme important step in research, trials saved lives.
2.11
Describe the current theories about processes responsible for the movement of materials
through plants in xylem and phloem tissue
Vascular tissue consists of xylem which conducts water and mineral ions up the plant form
roots to leaves, and phloem which translocates the products of photosynthesis and other
organic products both up and down the plant.




2.12
Process of movement of materials in xylem tissue
Movement of water and mineral ions up the plant.
Water enters root by osmosis and transpiration pull draws water up the stem
Cohesion between water molecules causes water to form continuous stream up the plant
and ‘pulls’ water up.
Adhesion between water molecules and xylem vessels also help to draw water up
Choose equpiment or resources to perform a first-hand investigation to gather first-hand
data to draw transverse and longitudinal sections of phloem and xylem tissue
[Insert diagram]
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3. Plants and animals regulate the concentration of gases, water and waste products
of metabolism in cells and in interstitial fluid
3.1 Explain why the concentration of water in cells should be maintained within a narrow
range for optimal function



Cell metabolism controlled by enzymes, each enzyme requires specific conditions for
optimal efficiency e.g. specific pH, temp, ion concentration
Water in cells determines the osmotic pressure of cells
Change in concentration of water may interfere with function of enzymes and metabolism
disrupted
3.2 Explain why the removal of wastes is essential for continued metabolic activity
Main metabolic wastes = carbon dioxide, excess salts and water and nitrogenous wastes

Accumulation of wastes may inhibit enzyme functioning and prevent cells from undergoing
normal metabolic functioning. E.g. high levels of ammonia will kill cells and excess water will
change concentrations affecting enzyme activity

Accumulation of wastes may also interfere with reaction rates and an osmotic imbalance
adversely affecting membrane functioning
3.3 Identify the role of the kidney in the excretory system of fish and mammals
Filtration, absorption, secretion







Filtration: this is a continuous cycle in the renal corpuscles.
Reabsorption: in the kidneys is defined as the movement of substances out of the renal
tubules back into the blood capillaries located around the tubules
Secretion: occurs when substances move into the distal and collecting tubules from the
blood of capillaries around them.
The kidney however has other subtle functions which include:
Releasing hormones
Control blood pressure
Help produce red blood cells
Produce vitamin D which helps the bone remain strong and healthy
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Feature
Kidney
Mammal
An excretory organ that filters
blood and removes
nitrogenous wastes
Saltwater fish
An excretory organ
that filters blood and
removes nitrogenous
wastes
Freshwater fish
An excretory organ
that filters blood and
removes nitrogenous
wastes
Structure
Many nephrons
Filtration
High blood pressure in
glomerulus forces ultrafiltration
Depends upon water intake
Simple structure with
few small glomeruli
Love filtration rate
Simple structure with
many large glomeruli
High filtration rate
Small quantity
Large very dilute
Urine produced
3.4 Explain why the processes of diffusion and osmosis are inadequate in removing dissolved
nitrogenous wastes in some organisms

Passive processes and will not occur unless sufficient gradient is present

Processes can also be very slow

Large, active, multicellular animals quickly accumulate toxic levels of nitrogenous wastes
and thus need other mechanisms
3.5 Distinguish between active and passive transport and relate these to processes occurring in
the mammalian kidney
Active transport
 Requires an input of energy for the movement across a cell membrane
Passive transport
 Does NOT require energy for movement across a cell membrane e.g. diffusion
and osmosis
In kidney:

Both active and passive transport occurs

Pressure in glomerulus causes water, ions and small molecules to filter into
bowman’s capsule

Reabsorption of glucose, amino acids and inorganic salts occurs by active
transport

As these solutes move out of the nephric filtrate, water follows by osmosis

Active transport of sodium causes more osmosis and salt and water levels are
thus adjusted to maintain homeostasis

Passive transport: once filtration occurs in bowman’s capsule, water returns via
interstitial fluid from tubules to capillary in process of osmosis
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3.6 Explain how the process of filtration and reabsorption in the mammalian nephron regulate
body fluid composition
Ultrafiltration: occurs when high blood pressure in glomerulus forces water, ions and small
molecules into Bowman’s capsule
Reabsorption: components that are needed by body are then selectively reabsorbed into blood
stream by tubules

By controlling reabsorption in the blood stream, the salt and water levels of the body fluids
are controlled.
3.7 Perform a first-hand investigations of the structure of a mammalian kidney by dissection,
use of a model or visual resource and identify the regions involved in the excretion of
waste products
Equipment:
 Sheep kidney
 Dissecting board
 Scalpel
 Probe
 Gloves
 Newspaper, magnifying glass
Risk assessment:


Be sure to safely dispose of kidney to avoid outbreak of disease
Use care when cutting kidney, cut from blade = infection
Method:
1. Observe outer shape of kidney and capsule
2. Identify tubes entering kidney – ureter, renal artery, renal vein
3. Cut kidney in half lengthways
4. Observe internall structure
5. Use probe to follow pathway from ureter into pelvis
6. Safely dispose of kidney
[insert diagram here]
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3.8 Gather, process and analyse information from secondary sources to compare the process
of renal dialysis with the function of the kidney
Dialysis = process which allows solutes dissolves in blood to diffuse across a
semipermeable membrane e.g. renal dialysis whereby waste products are removed
from blood when person has mild kidney failure
Feature
Structure
Kidney
1 million nephrons which filter the
blood
Renal dialysis
Haemodialysis occurs in hospital where
patient is attached via tube in veins, to
machine that circulates blood through
semipermeable filters and take out toxin in
blood. The procedure usually takes approx. 3
to 4 hours. Dialysers consist of three parts:
compartment for the blood, compartment
for dialysate and semipermeable membrane
separating the two
Function and
nitrogenous
wastes
Other functions
Removes urea from blood
Removes urea from blood
Concentrations of desired solutes can be
adjusted by altering the composition of the
dialysis to maintain natural concentration for
healthy blood
How often it
occurs
Maintains body balance of salts.
E.g. potassium, calcium etc.
Releases into the blood stream
hormones that regulate vital
functions including blood
pressure, red blood cell
production
Each day two kidneys excrete
about 1.5 to 2.5 litres of urine
Filtration and
reabsorption
Filters and reabsorbs required
materials
Haemodialysis - Can be done in short sessions
e.g. 3 to 4 hours in hospital
Peritoneal – needs to be performed every
day
Filters but no reabsorbtion
3.9 Outline the role of the hormones aldosterone and ADH (anti- diuretic hormone) in the
regulation of water and salt levels in blood
Aldosterone:
-
Steroid hormone secreted by adrenal gland
-
Regulates the transofer of sodium and potassium ions in kidney
-
Causes increased active transport of sodium ions from nephron distal
tubules
Water follows and is reabsorbed from tubeules
This causes concentration of solutes in blood to decrease and blood
pressure rises
Function:
Action
-
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Anti – diuretic hormones:
Function:
Action:
-
Produced from neurosecretory cells in hypothalamus in brain
Controls water reabsorption in the nephron
In kidney, increases permeability of distal tubules and collecting ducts
to water
- This increases the amount of water reabsorbed and concentration of
solutes decreases
Both are suppressed by a negative feedback system
3.10

Present information to outline the general use of hormone replacement therapy in
people who cannot secrete aldosterone
Hormone replacement therapy is a treatment given when a gland is not producing
enough of a particular hormone

Deficiency in aldosterone, can lead to Addison’s disease.

Without treatment, condition is lethal as incorrect sodium levels cause electrolyte
imbalances, hypertension and cardiac failure.

Treatment of Addison’s disease involves replacing hormones, e.g. oral doses of
fludrocortisone acetate, given once a day and adjusted to meet the needs of individuals
3.11
Analyse information from secondary sources to compare and explain the differences in
urine concentration to terrestrial mammals, marine fish and freshwater fish
Animal
Marine fish
Urine concentration
Varies. Mammals live in desert=
highly concentrated,
herbivorous= less
concentrated
Highly concentrated
Fresh water fish
Dilute
Mammal
Reason for the difference
Issue of conserving water, while
at same time removing
nitrogenous wastes
Problem of osmosis.
Concentration of dissolved
substances in seawater usually
low. Therefore, water tends to
move out by osmosis and salts
diffuse in.
Concentration of dissolved
substances usually higher in the
body then they are in the
environment. Water therefore
moves out of body by omosis.
Waste product = large
amounts of dilute urine
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3.12
Use available evidence to explain the relationship between the conservation of water
and the production and excretion of concentrated nitrogenous wastes in a range of
Australian insects
Ammonia: very toxic and must be removed immediately, either by diffusion or in very
dilute urine
Urea: toxic, but 100 000 time less toxic then ammonia, so it can be safely stored in the
body for limited time
Uric acid: less toxic then ammonia or urea, so can be safely stored in or on the body for
extended periods of time spinifex – hopping mouse and Wallaroo: lives in environment
with scarce water supplies
- Mammals release urea as their nitrogenous waste
- Urea is highly soluble in water
- Therefore by releasing a highly concentrated urine they conserve
water and can survive in the environment
Insects: release uric acid as their nitrogenous waste
- Insects are covered with a cuticle impervious to water, so they collect
water through tubules
- Uric acid is insoluble in water
- They conserve water by producing a dry paste of uric acid
3.13
Define enantiostasis as the maintenance of metabolic and physiological functions in
response to variations in the environment and discuss its importance to estuarine
organisms in maintaining appropriate salt concentrations

Enantiostasis
maintenance of metabolic and psychological functions in the absence of homestasis, in
an organisms response to a varying environment

Particularly important to estuarine organisms as salinity varies greatly and regulary


Estuary:
Region where fresh water meets salt water, e.g. tidal mouth of river
Organisms living in estuary environment experience large changes in salt concentration
over a relative short time span, with tidal movements and salt and fresh water mixing.
Importance of maintain an appropriate salt concentration
 Various bodily functions are affected when salt concentration of bodily fluids changes such
as activity of enzymes
 For maintenance of normal functioning, another body function must be change in a way
which compensates the change in enzyme activity
 For example, when salt concentration changes in the body, which reduces the efficiency
of an enzyme, it is compensated for by a change in pH, increasing the efficiency of the
same enzyme
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3.14
Process and analyse information from secondary sources and use available evidence
to discuss processes used by different plants for salt regulation in saline environments

Most plans cannot tolerate high salt concentrations in the support zone as it leads to water
stress. Salt accumulates in the leaves and is toxic.

Grey mangrove
-
Found in Sydney estuaries
Secretes salt through secretory glands on their lower leaf surfaces
Salt crystalises upon evaporation and then is washed or blown away

Aegiceras cornicalatum
- Mangrove found on NSW coast
- Stores salt in leaves then drops leaves

Sarcocornia quinqueflora
- Salt marsh plants
- Accumulates salts in swollen leaf bases which fall off, thus removing
excess salts
3.15

Describe adaptations of a range of terrestrial Australian plants that assist in minimising
water loss
Eucalyptus
Leaves hang vertically, thick waxy cuticles
How this minimises water loss:
- Less surface area exposed to midday sun
- Less transparent and evaporation
- Reflective, prevents evaporation

Spinifex grass
Leaves coil around underside
How this minimises water loss:
- Stomates on underside are protected from heat, wind
- Water loss from transpiration reduced

Acacia Spp
Extensive root system with root nodules
How this minimises water loss:
- Increases ability to absorb water when available
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3.16
perform a first-hand investigation to gather information about structures in plants that
assist in the conservation of water

Make thin cross section of spinifex and cactus

Cactus – stems store water
- Generally cactuses live in dry arid conditions, so the storing of water is
advantageous when water availability is low
Casuarina:
- Leaves reduced to scales
- Reduces transpiration
Spinifex grass
- Stromates on underside of curled leaf
- Results in water having difficulty transpiring and water loss is reduced



Hairs on the underside
Restricts movement of water away from plant and hinders air
movement resulting in less transpiration and water loss
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