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Maintaining a Balance
Chapter 1: Most organisms are active in a limited temperature range.
1. Identify the role of enzymes in metabolism, describe their chemical composition and use a simple model to
describe their specificity on substrates

Metabolism: The sum of all chemical reactions occurring in the body
There are two types of metabolic reactions; anabolic and catabolic:


Anabolic reactions: building up large molecules from small ones.
Catabolic reactions: breaking down molecules into smaller parts.
These reactions occur through the use of a:
 Catalyst: Substances that speed up the rate of a chemical reaction but are not used up in the process.
 Enzyme: A biological catalyst (a 3-dimensional protein manufactured by cells, that speeds up the rate of
reactions in organisms but are not used up in the process).
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Role of an Enzyme in Metabolism:
 The role of an enzyme in a metabolism is to increase the rate of chemical reactions by decreasing the
activation energy of a reaction. If these reactions were allowed to occur at their normal rate it would be
too slow to keep an organism alive.
Enzyme Chemical Composition:
 Enzymes are proteins and are therefore made from amino acids. The amino acids of a protein molecule
form long chains that fold over to form a three dimensional shape.
 Every type of enzyme has a specific shape as it is made up of a specific pattern of amino acids. Within
their structure, enzymes have active sites that are usually composed of three or four amino acids. The
active sites are the areas that substrates will bind to and catalyse chemical reactions.
 When an enzyme binds to a substrate it makes a new molecule called the enzyme substrate complex.
Due to the specificity of their active sites, each type of enzyme will only catalyse one reaction type.
Specificity on Substrates:
 Enzymes act on substrates. It was once believed that only one specific enzyme (or combination of
enzymes) can react with one specific substrate (or combination of substrates).
 This is demonstrated by the lock and key theory proposed by German scientist Emil Fischer in 1894.
 It explains enzyme action by likening the enzyme to a lock and substrates to a key. Only a specific key is
able to open its matching lock. Just as the key is specific to the lock so is a substrate specific to an
enzyme. An enzyme will not work unless the substrate matches its active site. Only then will the reaction
be catalysed.


However it was later discovered that the substrate enters in and binds to the enzyme shaping the active
site and properly aligning the enzyme for the reaction to take place. Other substrates may fit into the
active site, but unless they are able to properly shape the enzyme, a reaction will not be catalysed.
Induced fit theory by US scientist Daniel Koshland, 1958.
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2. Identify the pH as a way of describing the acidity of a substance


pH: A measurement of the acidity or alkalinity of a substance.
pH < 7 is acidic, pH of 7 is neutral and pH above 7 is basic or alkaline.
3. Explain why the maintenance of a constant internal environment is important for optimal metabolic efficiency





Enzymes usually function at a specific temperature and pH range. Where the enzyme functions in the
body determines what its optimum temperature and pH range will be.
If an enzyme is subject to extreme pH and temperatures changes outside its normal ranges, it firstly
slows the rate of the reaction they are catalysing and then result in change shape and block the active
site of substrates.
This is called denaturing. Denaturing means that an enzyme is useless as the substrate cannot bind with
the active site and will no longer be able to function properly or catalyse reaction. Once an enzyme is
denatured the change is permanent, the enzyme cannot be reformed into its original shape.
Changes in temperature and pH can breaks bond in the protein molecule and overall disrupt their threedimensional shape – making them unspecific to the substrate.
The maintenance of a constant internal environment is important for optimal metabolic efficiency as it
maintains the optimum level that the enzymes can react at while maintaining their specificity.
Why is it important to be specific?

The specificity shown by enzymes confers upon
living systems enormous potential for very precise
control of chemical reactions. This precise control is a
basic feature of life.
4. Describe homeostasis as the process by which organisms maintain a relatively stable internal environment




Homeostasis: is the maintenance of a stable internal environment, irrespective of external conditions.
It is a process by which organisms maintain a relatively stable environment.
In an organism enzymes control all the metabolic processes. Enzymes work optimally in an environment
where their optimum conditions are met. If the environment surrounding the organism does not remain
relatively stable then the rate of enzyme catalysed reaction decreases. This decreased rate could affect an
entire metabolic pathway that might produce an essential compound and could result in fatality. Therefore
maintaining the homeostasis is important!
In multicellular organisms, cells need to maintain their internal balance regardless of the external
environment. An external environment may vary greatly but the internal environment can be relatively
unchanging and stable. This is because when metabolic reactions occur in cells they cause changes in the
intracellular environment but our bodies have processes that quickly act to counter any changes and return
to the stable state. This continual maintenance is called homeostasis. External environments have abiotic
and biotic factors that affect it but an organism’s internal environment is more variable as it is controlled by
the organism’s body processes.
Note:



Enzymes often have the prefix “ase”
Substrates often have the prefix “ose”
E.g. the substrate, cellulose is broken down by the enzyme, cellulase.
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5. Explain that homeostasis consists of two stages: detecting changes from the stable state, counteracting changes
from the stable state


Negative Feedback System: is where the response to the stimulus is to reduce and counteract the change. It
causes the body to respond so that a reversal in the direction of a change occurs.
Positive Feedback System: is where the response to a stimulus is to amplify the change instead of reducing it.
This does not result in homeostasis.
The Negative Feedback System:
Stage 1: Detecting change from a stable state:
» In this stage a receptor detects a change in a specific variable from the desired stable level of the
variable.
Stage 2: Counteracting changes from the stable state:
» An effector receives the message that an undesirable change must be counteracted and the variable
restored to its desired level.
This is how the negative feedback system occurs:
1. Stimulus: All organisms receive information from the various parts of their bodies and from their
environment in the form of stimuli. It can be either external or internal.
2. Receptor: A variation in either the internal or external environment is detected by a receptor. Sight, sound,
touch, taste and smell are all receptors.
3. Control Centre (Central Nervous System – CNS): Once a variation is detected, a message is sent to the control
centre. This then replies by sending a message to the effector to counteract the variation.
4. Effector: The effector is normally either a muscle or gland that responds to the message and counteracts the
variation.
5. Response: This is the action of counteracting the variation.
6. Outline the role of the nervous system in detecting and responding to environmental changes



The nervous system is made of the brain, the spinal cord and sensory and motor neurons.
The nervous system enables the detection of external and internal environmental changes to the body and
then coordinates the responses the body will make to counteract these changes.
It is made up of two interacting elements, the central nervous system and the peripheral nervous system:
Central Nervous System:
 Composed of the brain and the spinal chord.
 The spinal chord transmits messages from the receptor organs via the sensory neurons to special regions of
the brain.
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
When one of these regions receives stimuli from the sensory neurons it then coordinates the correct
response necessary to counteract the change by sending out messages to the effector organs via the motor
neurons.
Peripheral Nervous System (PNS):
 Composed of all neurons outside the Central Nervous System (CNS). These include sensory and motor
neurons as well as the cranial nerves and spinal nerves.
 Sensory neurons are nerve cells within the nervous system responsible for converting external stimuli from
the organism's environment into internal electrical impulses e.g. touch, smell, sight.
 Sensory neurons transmit messages from the receptor organs to the CNS (brain).
 Motor Neurons transmit messages from the CNS (brain) to the effector organs to activate a response.
 A motor neuron conveys impulses from the CNS to a muscle, gland, or other effector tissue.
7. Identify the broad range of temperatures over which life is found compared with the narrow limits for individual
species.



Life is found over a broad range of temperatures on planet earth. Where climatic temperature can vary from
-75oC to above 50oC.
However, most individual species have narrow temperature limits and they cannot exist in habitats that have
great varying temperatures.
This is because they possess behavioural and physiological adaptations that enable them to maintain their
temperature within this narrow range.
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: are organisms whose body temperature is determined by their surroundings. e.g. plants,
invertebrates, amphibians, reptiles and fish
Endotherms: are mammals that have physiological structures that enable them to maintain their body
temperature within a narrow range irrespective of the ambient temperature. e.g. birds and mammals
Physiological Adaptations: referring to adaptations in relation to how the organism functions
Structural Adaptations: referring to adaptations in relation to the organism’s shape and size
Behavioural Adaptations: referring to adaptations in relation to how the organism acts.
Red Kangaroo (Endotherm):
The red kangaroo is the largest marsupial in Australia. It lives in the grasslands of dry arid central part of the
country. In this habitat, the red kangaroo experiences temperatures varying from 5oC in the winter months to
38oC in the summer months. For this reason, it needs many adaptations to accommodate these dramatic
changes in temperature and retain its optimum temperature range at 37.5oC.
Climate
Physiological
Structural
Behavioural
Cold
conditions
(winter
months)
Increased metabolic
rate to create more
heat within the body
Vasoconstriction
Layer of fur creates and layer of insulation
between the skin and the hair and allows the
kangaroo to stay warm
Basking in the sun
Warm
conditions
(Summer
months)
Decrease in metabolic - Panting to release heat
rate which reduces
- Exposed areas of skin on the forelegs to
the amount of heat
increase evaporative cooling of the blood from
within the body
this area- vasodilation.
- Shunting blood from the tail to the exposed
areas of the skin on the forelegs to increase
heat loss.
- Nocturnal
- Licking forelegs to
increase evaporation
from the skin
- Sitting in the shade
5
Diamond Python (Ectotherm):
The diamond python lives in a variety of habitats including rainforests, temperate forest, grassland, caves and
hollow trees. It eats small mammals, bats, birds and lizards. Its optimum temperature range is around 20oC
however this depends on the ambient temperature the python’s surroundings.
Climate
Cold conditions
(winter months)
Physiological
Lies on eggs and
shivers to increase the
temperature of
incubation
Structural
Dark in colour to absorb heat and
can therefore tolerate colder
temperatures than most snakes
Warm conditions
(summer months)
Behavioural
» Basks in the sun to raise body
temperature
» Hibernation
» Migration to warmer areas
» Is nocturnal, so hunts at
night to escape the heat
during the day
» Burrowing during the day
Compare the responses of endotherms and ectotherms:
Endotherms need to have a high metabolism rate to maintain this optimum temperature rate in cold conditions
and as a result need to eat large amounts. Ectotherms do not need to do this however they have greater
restrictions placed on their activity as a result. In hot conditions endotherms must have specific adaptations to
these environmental changes to regulate heat gain so not to raise their temperature above their optimum
temperature level as this can cause severe damage. This is the same for both endotherms and ectotherms in
relation to cold climates. Ectotherms are not found in extremely cold climates.
9. Identify some responses of plants to temperature change
»
Plants are ectothermic and so cannot maintain a constant temperature. Therefore they have a range of
adaptations to help them survive in a variety of temperatures.
Response to
Temperature Change
Leaf Fall
Radiation
Heat-shock Proteins
Transpiration
Die back
Orientation of leaves
Ice formation between
cells
Reason
Many plants in hot conditions reduce their surface area that is exposed to the sun by
dropping their leaves. This reduces the amount of water lost in transpiration.
Some plants reduce the amount of heat received by having shiny leaves that reflect solar
radiation.
Produced by plants when they are under stress from very high temperatures. They are
thought to stop the denaturing of the enzymes within the cell, so allow normal cell
reactions to continue.
The movement of water through the plant helps to cool the plant during hot conditions.
This is also effecting when evaporation of water occurs from the stomates of the leaf
In harsh conditions, shoots of a plant may die. However the soil and roots will begin to
grow again when favourable conditions return
Some plants orientate their leaves in such a way that it reduces the amount of sun rays
that make contact with the surface area of the leaf. e.g. eucalyptus
Most plants are able to tolerate fairly low temperatures compared to animals. This is due
in part to their cell walls as when temperatures drop bellowing freezing, ice will form
outside of the plant cells. This is because the solution within the plant cells is higher in
solutes (and therefore higher freezing point) than the solution between the cells. Ice will
therefore form between the plant cells, which are protected from ice crystals by cell
walls. However this is ineffective if temperatures drop too quickly, such as during a frost.
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10. 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)
--------------------------------See “Enzyme Action” Prac Experiment---------------------------------------See “Substrate Concentration and Enzyme Activity” Prac Experiment------------------------See “First-hand Investigations with Enzymes” Prac Experiment---------------------------------See “Effect of pH on enzyme activity” Prac Experiment-------------------See first assessment task- practical on enzymes.
11. Gather, process and analyse information from secondary sources and use available evidence to develop a model of
a feedback mechanism
-----------------------See examples of feedback mechanisms in notes (point 5) -------------------------
12. Analyse information from secondary sources to describe adaptations and responses that have occurred in
Australian organisms to assist temperature regulation
------------------------------------------See questions in notes (point 8) ----------------------------------------
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Chapter 2: Plants and animals transport dissolved nutrients and gases in a fluid medium.
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
Substance
Carbon Dioxide
(a waste product of respiration in cells)
»
»
»
»
Oxygen (needed for respiration)
Water (solvent of plasma)
Salts (composed of positive and negative ions, used for
body processes)
Lipids (digested lipids are re-synthesised into triglycerides in the epithelial cells that line the small
intestine)
Nitrogenous wastes (metabolic wastes excreted by the
body)
Other products of digestion (amino acids, sugars,
vitamins, glycerol and nitrogenous bases)
»
»
Transported form
Dissolved in plasma
Converted into carbonic acid and then hydrogen
carbonate ions in red blood cells
Bind to haemoglobin forming carbaminohemoglobin
Attached to haemoglobin in red blood cell forming
oxyhaemoglobin
Dissolved in plasma
Dissolved in plasma as ions
»
Wrapped in a coat of protein to form a package
called chylomicron
»
Dissolved in plasma as urea, uric acid and creatinine
»
Mainly water soluble and are transported dissolved
in plasma
2. Explain the adaptive advantage of haemoglobin



Haemoglobin is a complex protein molecule which is made up of four long amino acid chains, each one
assembled around the atom of iron. Iron easily combines with oxygen.
Oxygen is not very soluble in water and so cannot be carried efficiently dissolved in the blood plasma. Most
of the oxygen is carried by haemoglobin in the red blood cells. Thus, the presence of haemoglobin in red
blood cells in blood increases the blood's capacity to carry oxygen. 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.
At high altitudes, blood is not able to absorb as much oxygen as at sea level. The human body adapts to what
is effectively oxygen deprivation by initially increasing heart rate, breathing rate, then the number of red
blood cells (more haemoglobin), then density of capillaries.
3. Compare the structure of arteries, capillaries and veins in relation to their function
Blood Vessel
Structure
» Thick muscular
walls
Arteries –
blood travelling » Walls are
elastic
away from the
heart.
» Smooth inner
(oxygenated)
layer
» Thinner
Veins – blood
muscular walls
travelling
towards the
» Wider
heart.
diameter
(deoxygenated) » Valves
Capillaries» A single layer
connect
of flat
»
»
»
»
»
»
»
»
Function
Cope with the stress of the high pressure of blood being pumped out to the body.
Enables expansion and contraction to adjust to the amount of blood flowing
through at any one time e.g. when vasodilation or vasoconstriction occurs.
Allows blood to flow with ease, away from the heart in one direction.
These three aspects of an arteries’ structure allow the artery to expand as it fills
with blood when the heart beats and contract as the heart relaxes. This results in
a force to help push the blood through the body.
This is in response to the lessened amount of pressure as the blood is not being
pumped hard as it returns to the heart.
Allows increased amounts of blood to flow through veins and return to heart
The valves prevent blood from flowing backwards in the vein since the force and
direction of the blood flow is against gravity.
High surface area to volume ratio. Allows a single file of red blood cells to pass
through, maximising the opportunity for the exchange of gases, nutrients and
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arteries and
veins, surround
all tissue cells.
overlapping
cells
wastes between the blood and the tissue cells. In this way the body’s tissues are
efficiently supplied with the substances they need while wastes are removed.
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.

The chemical composition of blood changes as it moves around the body. This is as a result from the
continuous exchange of substances between the blood and the surrounding tissues.
 In general, blood moving through/towards the body’s tissues delivers oxygen and glucose for cellular
respiration as well as nutrients.
 In general, blood moving away from the body’s tissues carries carbon dioxide and nitrogenous wastes
for disposal.
Tissue
Main Changes in Blood
» Increase in oxygen
Lung
» Decrease in carbon dioxide
» Increase in glucose and other products of digestion (amino acids, lipids,
Villi of small intestine
vitamins, minerals, water)
Kidneys
» Decrease in nitrogenous wastes (salts and water to form urea)
» Decrease in oxygen
Other body tissues
» Decrease in glucose
» Increase in carbon dioxide
5. Outline the need for oxygen in living cells and explain why removal of carbon dioxide from cells is essential
Need for oxygen in living cells:
 Oxygen is transported from the lungs to the tissues throughout a body.
 These cells need oxygen so that the process of cell respiration can occur.
 Cell respiration is essential as it provides energy that is needed for metabolic process (e.g. protein synthesis)
and if these processes do not occur it can result in fatality.
Need for removal of carbon dioxide in living cells:
 The products of respiration are carbon dioxide and water.
 For most living cells that do not photosynthesise, carbon dioxide is a waste that must be removed as it can
become poisonous if too concentrated in a cell.
 A high concentration of carbon dioxide dissolved in the cytoplasm of a cell can lower of the pH level making
the liquid more acidic.
 This would result in denaturing enzymes in the cell and lowering their activity which can result in fatality of
the cell.
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6. Describe current theories about processes responsible for the movement of materials through plants in xylem and
phloem tissue
Xylem (dead tissue)
– Transports water and dissolved minerals
» PASSIVE TRANSPORT
Phloem (living tissue)
– Transports sucrose, produced in
photosynthetic tissue to other regions of a
plant, as well as hormones and any other
organic material made by the plant.
» Transport of the organic material
through the plant is called translocation.
» The organic material is actively
transported around the plant through
the use of sieve tubes.
» The energy required for the active
transport is provided by companion cells.
» A high concentration of water in the soil is absorbed by the root
hairs which have a lower concentration of water. This is caused by
osmosis and is called osmotic pressure.
» The water then moves through the cortex into the xylem in the
vascular tissue and transported through the plant. This overall
process is called root pressure.
» Gases enter and leave the leaf through the stomata. Most of the
water lost by the plant is in transpiration through the stomata.
» The walls of the mesophyll cells are moist and when the sun shines
the air spaces around them evaporate the water.
» As water evaporates, water moves out of the cells to ensure that the
walls of the mesophyll are kept moist. In turn, water moves from the
small xylem vessels into the mesophyll cells. This is called
transpiration pull.
» When the sugar leaves the phloem to
enter a sink (a place that uses organic
material made elsewhere) there is an
increase of water in the sieve tube in
that region. This increases pressure in
the sieve tubes.
» Water then moves out of the sink tubes
and this results in higher pressure in the
sieve tube and lower pressure at the sink
tube.
» The difference in pressure pushes the
materials to move to the sink to be used
in different ways.
» ACTIVE TRANSPORT
» Water has tensile strength because of the cohesion of the molecules.
They tend to stick together as well as to the tube by adhesion. The
smaller the diameter of the tube the molecules are in, the greater
the tensile strength. This results in a capillary action that helps the
water move through the plant.
7. Perform a first-hand investigation to demonstrate the effect of dissolved carbon dioxide on the pH of water
----See “Effect of Dissolved Carbon Dioxide On the pH of Water” Prac Experiment---Blowing into the cup of water with indicator and/or limewater.
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8. 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


Method:
» The diameter of the LP field was determined using a grid
» A diameter of the HP field was calculated
» A prepared slide of blood cells was observed at HP, and the diameter of red blood cell and white
blood cells estimated
» Diagrams of each were drawn.
o Red blood cells: 6-8 microns
o White blood cells: 7-21 microns
Results:
» Red blood cells are generally smaller than white blood cells
» Red blood cells appear biconcave, while white blood cells usually appear disk shaped, and are
spherical
» Red blood cells have no nucleus, while white cells have a darkly staining nucleus
Under x100: FOV (field of view) is 400 µm
Under x400: FOV is 160 µm
Lymphocyte- Small type of white blood cell.
Red Blood Cells
9. 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
What is oxygen
saturation?
How does
measuring these
concentrations
help?
Who needs this
tested
/monitored?
»
»
»
»
Oxygen saturation is relating to the measured amount of oxygen in the blood.
Normal oxygen saturation in the human body is about 96%.
Helps doctors in diagnosis of patients and in monitoring them while in hospital.
Gives information about the ability of the lungs both in providing oxygen to the body and
removing carbon dioxide from the body.
» Gives information on the kidneys’ ability to reabsorb or excrete bicarbonate ions to maintain
normal body pH.
Patients:
» undergoing any procedure that requires anaesthesia or sedation
» with abnormal breathing
» in intensive care
» who are premature new born babies
» who shows dangerously low oxygen levels or high levels of carbon dioxide
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How is it
measured?
What is a
biosensor?
What is a Pulse
Oximeter?
What is Arterial
Blood Gas (ABG)
Analysis?
Advances in biotechnology and electronics have resulted in the production of biosensors that have
made analysing blood more accurate.
In hospitals, a Pulse Oximeter is used to monitor the oxygen saturation of the blood and in dramatic
cases, blood is taken from an artery for Arterial Blood Gas Analysis.
A sensor is a device that translates a physical or chemical property into an electrical signal that can
be measured. The key component is the transducer or signal-converting element that converts the
property to be measured into a signal.
» Pulse oximeters measure the amount of oxygen in arterial blood (blood being pumped from the
heart to the body cells).
» They consist of a sensor or probe that is attached to a part of the body such as a fingertip.
» When oxygen combines with haemoglobin the colour of the blood changes from dark red
(unsaturated) to bright red (saturated).
» Light from two light emitting diodes is passed through the finger and the amount of light energy
transmitted is detected by two light detecting sensors. The light energy varies depending on the
level of oxygenation of haemoglobin in the blood.
» Two diodes are commonly used, one emitting red light (650nm) and the other infrared (940nm).
Oxygenated blood absorbs red light whereas deoxygenated blood absorbs more infrared light.
There is a large difference in the amount of red light absorbed by the oxyhaemoglobin compared
to haemoglobin.
» By calculating the absorption at the two wavelengths the processor can compute the proportion
of haemoglobin which is oxygenated.
» The signal is first amplified, then the oxygen saturation is calculated and the result displayed on
the screen. An alarm rings if oxygen saturation falls below a certain level, usually about 90%.
» Oximeters give no information about the level of carbon dioxide and therefore have limitations in
the assessment of patients developing respiratory failure due to carbon dioxide retention.
» An ABG analysis is a blood test that is performed using blood from an artery.
» The test is used to determine the pH of the blood, the partial pressure of carbon dioxide and
oxygen, and the bicarbonate level. Many blood gas analyzers will also report concentrations of
lactate, hemoglobin, several electrolytes, oxyhaemoglobin, carboxyhaemoglobin.
» Arterial blood for blood gas analysis is drawn from an artery. The radial artery is easily accessible,
can be compressed to control bleeding, and has less risk for occlusion.
» Once the sample is obtained, care is taken to eliminate visible gas bubbles, as these bubbles can
dissolve into the sample and cause inaccurate results. The sealed syringe is taken to a blood gas
analyser and analysed within 30 minutes (generally).
10. Analyse information from secondary sources to identify the products extracted from donated blood and discuss
the uses of these products
Most donated blood is separated into its components—plasma, red blood cells, white blood cells, and
platelets—before being stored. This allows the blood of a single donor to be used for several patients who have
different needs. Blood is separated by means of centrifugation, a process in which the blood is rapidly spun so
that the heavier blood cells and platelets separate out from the lighter plasma. Whole blood is given to patients
where major functions of the blood, such as oxygen carrying capacity, are impaired, or where more than 20% of
blood has been lost and there is a decrease in blood pressure.
Plasma, the liquid part of blood, can be dried into a powder or frozen. Fresh frozen plasma and freeze-dried
preparations containing clotting factors are used to treat patients with hemophilia. Hemophilia is an inherited
disorder in which certain clotting factors are missing in the blood, resulting in excessive bleeding. Concentrated
red blood cells are used to transfuse patients with anemia, a condition in which the blood contains an
insufficient number of red blood cells. White blood cells and platelets are used for transfusions in patients who
have a deficiency of these components in their blood.
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Component
Whole blood
Composition
Cell and plasma
Red blood cells, white blood cells, come
platelets and little plasma
Platelets
Plasma, all coagulation factor
Lymphocytes, neutrophils, some red
blood cells and platelets
Blood cells
Platelets
Plasma
Granulocytes
Use
Volume replacement in cases with large blood loss
Anaemia
Severe bleeding
Bleeding, where there is a deficiency in coagulation
Low neutrophil count
11. 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
What is
artificial
blood?
Why is it not
always used?
Why does it
exist?
What is the
demand for
it?
What
research
exists today?
What has
been
achieved
today?
A blood substitute that can be used to provide fluid volume and carry oxygen in the vessels. It
remains in circulation until blood volume is restored and then artificial is safely excreted.
» Is routinely used but not commonly. This is because it only transmits oxygen but not
nutrients, so cannot be used in long term treatments.
» Also it does not contain white blood cells, so cannot resist viruses from external
environment.
» There are not enough blood donors
» There is a shortfall in blood supply
» It has a longer shelf life than donated blood
» It is easily produced and developed at a fast rate and works for all blood types
Scientists have been trying to develop a blood substitute since the 1930s. The military have
been seeking a viable product since the 1970s and commercial ventures have added to this
research since the early 1980s.
Northfield Laboratories Inc in Chicago have developed ‘Poly Home’. This is basically recycled
human blood that is universally compatible, substantially free of viral contamination and has a
one-year shelf life.
Perfluorocarbons:
These are compounds derived from hydrocarbons by replacement of hydrogen atoms by
fluorine atoms. They are commonly used in eye surgery as temporary replacements of the
vitreous humour in retinal detachment surgery.
Plasma substitutes:
Any liquid used to replace blood plasma and volume of blood. It is also used to treat
dehydration.
12. Choose equipment or resources to perform a first-hand investigation to gather first-hand data to draw transverse
and longitudinal sections of phloem and xylem tissue
---------See “Investigating the movement of materials in plants” Prac Experiment------Celery Experiment in coloured water.
13
Chapter 3: Plants and animals regulate the concentration of gases, water and waste
products of metabolism in cells and in interstitial fluid.
1. Explain why the concentration of water in cells should be maintained within a narrow range for optimal function
Water inside a cell is essential for life. Too little or too much can result in serious problems and most cells will die
if their water content is changed significantly.
It is necessary for many reasons:
 It is the medium that transports and distributes many substances (such as nutrients and wastes) in and
between cells.
 It is the solvent in which many important ions and molecules required for metabolic reactions are dissolved.
They are only able to move when in aqueous solution as can they diffuse across and between cells.
 Metabolic reactions that occur within cells can only occur in solution.
 Water itself is a reactant or product of many cellular reactions e.g. cellular respiration
 For optimal functioning of cells is reliant on their water content being kept within a very narrow range. The
concentration water inside the cell (intracellular fluid) must match the concentration of water outside the
cell (interstitial fluid). This is called isotonic.
 If these concentrations do not match, water will move by osmosis from the area of higher concentration to
lower concentration. This leaves cells venerable to losing or gaining too much water.
2. Explain why the removal of wastes is essential for continued metabolic activity
------------------------------------See Point 5 in Chapter 2-------------------------------------

Metabolic wastes, particularly nitrogenous wastes that are the by-products of the breakdown of
proteins and nucleic acids, are toxic to cells and must therefore be removed quickly. Nitrogenous wastes
have the ability to change the pH of cells and interfere with membrane transport functions and may
denature enzymes.
Metabolic wastes are the product of metabolic reactions. If they are not removed their concentration in
the cell increases. This inhibits the reactions that produce them, interfering with normal metabolic
activity.
3. Identify the role of the kidney in the excretory system of fish and mammals
 The kidney is part of the urinary system and is the main organ involved in the excretion of wastes and
osmoregulation in fish and mammals.
» Osmoregulation: maintenance of a constant concentration of salt ions and therefore water
levels within the body regardless of the concentrations within the environment
 The role of the kidney is to:
» Excrete wastes
» Maintain osmoregulation
» Maintain appropriate pH levels in the blood
4. Explain why the processes of diffusion and osmosis are inadequate in removing dissolved nitrogenous wastes in
some organisms
 In unicellular organisms, the excretion of dissolved nitrogenous wastes occurs solely by the processes of
diffusion and osmosis. These are both forms of passive transport.
 The cell membrane is selectively permeable, allowing water molecules to enter by osmosis when necessary
and nitrogenous wastes to exit by diffusion.
 However, multicellular organisms are too large to rely on the processes of diffusion and osmosis to excrete
their nitrogenous wastes. They are made up of millions of cells so therefore must rid themselves of their
wastes by other methods.
 Active transport is one method whereby ions are moved against a concentration gradient through proteins.
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5. Distinguish between active and passive transport and relate these to processes occurring in the mammalian kidney

Passive Transport: diffusion of molecules from regions of high concentration to low concentration without
the expenditure of energy
 Active Transport: The net movement of particles against a concentration gradient from an area of high
concentration, with the expenditure of energy
The mammalian kidney is designed to use active transport to move ions against their concentration gradient and
therefore excrete wastes.
Process
Diffusion
Osmosis
Active
uptake
Secretion
Definition
The movement of substances from areas
where they are in high concentration to
regions where they are in low
concentration.
Osmosis is the movement of water only
through a semi-permeable membrane
from a region where there are less solutes
in the water to a region where there are
more solutes. (Region from higher to lower
concentration)
Where the cell membrane actively selects
which substances can pass through it into
the cell. Large protein molecules in the cell
membrane are involved in this.
The cells lining the tubule can actively
secrete harmful substances into the tube.
Application to kidney function
Solutes in the filtrate will tend to diffuse out through the
tubule walls into the tissue fluid and the blood, but once the
concentrations are equal there will be no further net
diffusion. If all of a substance needs to be reabsorbed then
active uptake must occur.
98% of water needs to be reabsorbed from the filtrate and
returned to the blood. It can move by osmosis only if there
are more solutes outside the tubule than inside the tubule.
In order to absorb all the useful molecules from the filtrate,
active uptake must be involved. This is because diffusion will
no longer work once the concentration of the substance is
the same of the inside and outside of the tubule.
Drugs such as penicillin and aspirin and other poisons are
added to the fluid in the tube. Because a lot of the urea
which forms part of the glomerulus filtrate diffuses out of the
tubule, this must be secreted back into the tubule.
Most of the process of reabsorption is by active uptake. This is why the kidney has such a high respiration rate.
Water can only move by osmosis so the kidney must ensure that there is a high enough salt concentration
around the Loop of Henle to absorb the sufficient amounts of water.
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6. Explain how the processes of filtration and reabsorption in the mammalian nephron regulate body fluid
composition
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
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The functional unit of the kidney is called the nephron.
The nephron functions to filter the blood of metabolic wastes, make and secrete urine and reabsorb water
to maintain homeostasis. There are millions of nephrons in the kidney’s cortex and medulla.
The reabsorption of water from the urine allows the nephron to regulate body fluid composition.
Purpose of nephrons
» To reabsorb useful molecules
» Keep unwanted molecules in the tubule
» Balance the pH of the blood
» Maintain the correct osmotic balance in the blood (water/salt)
Part of the Nephron
Glomerulus
Bowmans Capsule
Proximal Convoluted
Tube
Loop of Henle
Distal Convoluted
Tube
Collecting Duct
Main function (and how it is achieved)
An area of high blood pressure in a knot of capillaries which has a semi-permeable membrane
allowing for the removal of small molecules and ions from the blood stream.
A cup shaped structure surrounding the glomerulus that collects material forced out of the blood
» The first substances reabsorbed by active transport are glucose, sodium chloride, bicarbonate
and potassium ions.
» Hydrogen ions are pumped into the tubule at this point to help maintain blood pH.
» Water is also reabsorbed by passive transport. (sodium gradient)
Water is reabsorbed into the blood through passive diffusion. If the concentration of blood is
very high then more water is reabsorbed.
» The end point for active reabsorption.
» Some sodium and potassium are reabsorbed here to adjust the pH of the blood.
» Water will also pass out by passive diffusion.
» The final filtrate is formed.
» Materials remaining after reabsorption of wastes move through this tubule.
» More water is collected into the bloodstream. The waste in the tubule is urine which is passed
into the pelvis of the kidney.
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7. Outline the role of the hormones, aldosterone and ADH (anti-diuretic hormone) in the regulation of water and salt
levels in blood
The kidneys play a major role in maintaining water and salt levels in the blood. They are aided by hormones
produced by the body’s endocrine system. The two main hormones involved in osmoregulation are Anti-diuretic
hormone (ADH) and Aldosterone.
 Aldosterone: hormone produced by the adrenal cortex that regulates salt and water balance
 Anti-diuretic hormone (ADH): hormone produced by the hypothalamus that control reabsorption of water in
the kidneys
»
»
»
Aldosterone
A consequence of low water levels is low blood
pressure, as a result of lessened blood volume. This
change in blood pressure is detected by the receptors
in the kidnies resulting in the release of Aldosterone
Produced by the adrenal glands located just above
each kidney
Aldosterone acts to control the reabsorption of
solutes, specifically sodium. The higher the level of
aldosterone, the more permeable the walls of the
nephrons are to sodium. So sodium ions and
therefore water are absorbed back into the blood.
»
»
»
»
»
Anti-diuretic Hormone
The hypothalamus has osmoreceptors that detect a rise
in the concentrations of solutes in the blood (low
concentration of water).
As a result ADH is released into the blood stream by the
pituitary gland
Travels in blood to distal tubule of kidney
Increase the permeability of distal and collecting tubule
walls so that more water is reabsorbed
This results in an increase in the amount of water
returned to the blood and a decrease in the amount of
urine produced.
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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
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Enantiostasis: maintenance of metabolic and physiological functions in response to variations in the
environment
Estuaries are areas where saltwater from the ocean mixes with freshwater from one or more rivers. This
results in fluctuating salt levels caused by tidal movements.
Organisms that live in this habitat undergo enantiostasis. This means they employ various tactics to cope
with changing salinity.
Organisms that have special physiological mechanisms that allow them to control salt levels in their bodies
are called osmoregulators. e.g crabs
Plant example, Grey mangrove (see point 15), Animal example, crabs and yabbies. The crabs and yabbies will
burrow down into the mud where salt levels are more stable to avoid the fluctuating saline levels of the
estuary tide.
Organisms that can tolerate their body salt levels moving up and down in parallel with the level of the
environment are called osmoconformers. They conform to the external environment. e.g. some species of
algae
9. Describe adaptations of a range of terrestrial Australian plants that assist in minimising water loss
Water loss generally occurs as a by-product of transpiration. If a plant needs to reduce water loss it must close its stomata
to do this. However, the plant also needs to photosynthesise and respire, processes that need the stomata to be open for
gas exchange.
Adaptation
Phyllodes
Plant
Acacia group
Reduce size of
leaves
Sunken stomates
Hairy Leaves
Leaf curl
Leaf shape
How?
Replaced leaves with a modified leaf steams called phyllodes. They are
green and able to photosynthesise life a leaf but contain fewer stomata per
square centimetre than normal leaves. Therefore reduces transpiration and
water loss for the plant.
Casuarina
Reduces the amount of stomata present on the leaf’s surface and therefore
equisetifolia
reduces transpiration stream.
Wollemi Pine
Leaves have stomates that are set into or ‘sunken’ into the leaf. The
stomates have no direct contact with the sunlight so water evaporation is
reduced.
Paper Daisy
Leaves and sometimes stems are covered in hairs to reduce water loss. The
hairs trap water that has evaporated from the plant, increasing the
humidity around this area. This humidity decreases the transpiration rate.
Flax Lilies
Will curl their leaves when temperatures get too high. Most of their
stomates are located on the upper side of their leaves so when the leaves
roll up, the stomates are on the inside protected from heat and
evaporation.
Native Pig Face Grows on sand dunes so exposed to sunlight practically all day. Leaves are
triangular in shape to reduce the surface area exposed to sunlight and
decreasing water loss.
10. 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
----------------------------See “Dissection of Kidney” Prac Experiment--------------------------
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11. Gather, process and analyse information from secondary sources to compare the process of renal
dialysis with the function of the kidney
Treatment
How it works
Advantages
Disadvantages
Haemodialysis- Renal Dialysis
 Blood is removed from patient’s artery
 Before passing through the dialyser an anticlotting factor called Heparin is added to the blood
 Passes through the dialyser – blood travels next to and in the opposite direction to dialysate,
maximising the concentration gradient between the blood and the dialysate.
 Separated by a cellulose acetate membrane that allows diffusion of wastes and excess water out
of the blood down the concentration gradient, since it has a lower concentration then the blood,
encouraging diffusion and osmosis.
 Water bath – maintained at body temperature (37oC) prevents shock and organ failure
 Roller pump – maintains pressure
 Staff organises treatment
 Only 3 sessions a week
 Regular contact with people in dialysis centre
 Inflexible treatment schedule
 Travel to dialysis centre and 3-5 hours for every session
 Two needle sticks to extract blood as part of treatment
 Cannot move during treatment
 Diet/fluid intake restrictions
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12. Present information to outline the general use of hormone replacement therapy in people who cannot
secrete aldosterone

The pituitary gland produces a hormone that influences the secretion of hormones from the
adrenal cortex, including aldosterone. If the adrenal cortex gland is affected by a disease (e.g.
Addison’s disease) it can result in the gland producing insufficient levels of all adrenal cortex
hormones. This includes the hormone aldosterone.
The pituitary gland is a pea-sized structure located at the base of the brain, just below the
hypothalamus and attached to it by nerve fibres. It is part of the endocrine system and produces
hormones which control other glands as well as various bodily functions.
As a result people with insufficient levels of adrenal cortex hormones require multiple hormone
replacement therapy.
This includes a synthetic form of aldosterone which is called fludrocortisone.
The replacement is needed because the aldosterone secreted from the adrenal gland carries out
the vital process of the control of blood pressure and body fluid composition.
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13. Analyse information from secondary sources to compare and explain the differences in urine
concentration of terrestrial mammals, marine fish and freshwater fish

Isotonic: When the two solutions have the same concentration of solutes. There is therefore no
net movement of solutes by diffusion and no net movement of water by osmosis
Hypertonic: The name given to the fluid which contains the greater amount of solutes. Water will
flow into a hypertonic solution by osmosis
Hypotonic: The name given to the solution which contains the lesser amount of solutes. Water
will flow out of this solution by osmosis.


Nitrogenous waste product
Ammonia
Urea
Uric acid
»
»
»
»
»
»
»
Toxicity
High
Medium
Low
Solubility in water
High
Medium
Low
Types of animals producing this waste
Fish
Terrestrial mammals
Insects, reptiles, birds
Freshwater Fish
Marine (Saltwater) Fish
Tissues hypertonic to surroundings
» Tissues hypotonic to surroundings
Concentration gradient results in a loss of
» Concentration gradient results in a loss of
salts and an uptake of water
water and an uptake of salts
Low concentrated urine- dilute urine
» Concentrated urine
Fish must counter these changes to maintain » Fish must counter these changes to maintain
homeostasis
homeostasis
1. Does not drink
1. Drinks seawater
2. Kidney contains glomeruli and secretes
2. Minimal urine produced. Kidneys lack
copious amounts of very dilute urine that
glomeruli. Tubules actively secrete
contains ammonia. Tubules actively
MgSO4
reabsorb NaCl.
3. Gill membranes are relatively
3. Gill membranes permeable to water
impermeable to water
4. Gills actively absorb ions. Some ammonia
4. Gills actively secrete sodium from
leaves gills at the same time
chloride cells; chloride ions follow.
Freshwater and saltwater fish are both osmoregulators.
Terrestrial Mammal
Mammals must produce urine to be able to
excrete their nitrogenous waste: urea
Oxidation of proteins results in urea, as well
as carbon dioxide and water
This can cause water loss
»
»
Desert Terrestrial Mammal
Produces very concentrated urine
Little water loss occurs as most is retained
through kidneys (long loop of henle)
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14. 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 is very toxic and must be removed immediately, either by diffusion or in very dilute
urine.
» It is the waste product of most aquatic animals, including many fish and tadpoles.
» Ammonia is the immediate product of breakdown of amino acids — no energy is required
to make it. It is highly soluble in water and diffuses rapidly across the cell membrane.
» However, it needs large quantities of water to be constantly and safely removed.
» Ammonia does not diffuse quickly in air.
 Urea is toxic, but 10 000 times less toxic than ammonia, so it can be safely stored in the body for a
limited time.
» It is the waste product of mammals, and some other terrestrial animals, but also of adult
amphibians, sharks and some bony fish.
» It is made from amino acids but requires more steps and energy to make than does
ammonia.
» It is highly soluble in water, but being less toxic than ammonia, it can be stored in a more
concentrated solution and so requires less water to remove than ammonia.
» It is a source of water loss for these species.
 Uric acid is less toxic than ammonia or urea, so can be safely stored in or on the body for
extended periods of time.
» It is the waste product of terrestrial animals such as birds, many reptiles, insects and land
snails.
» It is a more complex molecule than urea so it requires even more energy to produce.
» It is thousands of times less soluble than ammonia or urea and has low toxicity, which
means that little water is expended to remove it. This is a great advantage for survival.
 The longer the loop of henle for the animal the greater water preservation (live in desert)
Organism
Spinifex Hopping
mouse of Central
Australia
Terrestrial or aquatic
Waste product(s)
Terrestrial
Urea in a
concentrated form
Euro, Wallaroo
(Macropus
robustus)
Terrestrial
Concentrated urine
Insects
Terrestrial
Uric acid
Explanation
The animal lives in a very arid environment. It drinks
very little water and excretes urea in a concentrated
form, so that water can be conserved.
Euros have 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
Insects are covered with a cuticle impervious to
water. They conserve water by producing a dry paste
of uric acid.
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15. Process and analyse information from secondary sources and use available evidence to discuss
processes used by different plants for salt regulation in saline environments

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Halophytes: A plant that successfully inhibits areas of high salinity. Possess various adaptations to
assist them in surviving high salt level in their surroundings.
Most plants cannot tolerate salty condition in saline environments the solute concentration in the
soil is greater than it is inside the plant’s root and so water tends to move out by osmosis.
In addition, an excess of sodium ions inside cells inhibits enzymes activity and can result in a
decrease in the uptake of essential potassium ions.
Plant
Salt marsh plant
(Sarcocornia quinqueflora)
Atriplex (saltbush)
Palmer’s Grass (Distichlis
palmeri)
Northfolk Island Pine
»
»
»
»
»
Grey Mangrove
»
Process of Salt Regulation
Salt collected in swollen leaf bases then are shed from the plant
Sodium ions are concentrated in salt glands within the leaf which eventually
expand and burst, releasing the excess salt.
Salt leaves the plant through the cells on the leaf, builds up on the leaf surface and
is ultimately washed away
Exposed to salty air and prevent salt from entering their leaves by covering the
stomates with a thin layer of cuticle
Salt is secreted in from the cells of the plant onto the lower surface of the leaf and
into bark. The leaves are then dropped and water dissolves the salt off the bark.
The endodermis in the roots forms a barrier against the passage of most salt into
the xylem so the xylem contains reasonable fresh desalinated water.
16. Perform a first-hand investigation to gather information about structures in plants that assist in the
conservation of water
------See “Investigating Water Conserving Structures in Plants” Prac Experiment------Use Assignment
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