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The MacRobertson Girls’ High School
VCE Biology – Unit 1
Name __________________
Exam Preparation 2013
Short Answer Questions: Suggested ANSWERS
1. Describe the processes of simple diffusion, facilitated diffusion, osmosis and active transport AND provide 1
example of each.
Simple diffusion: Net movement of molecules or ions from a region where it is in high concentration to a region where it
is in lower concentration (i.e. Net movement along or down a concentration gradient). This relies on the kinetic energy of
the moving molecules and does not require the expenditure of ATP (it is said to be passive):
Examples:

movement of oxygen from alveolus into lung capillary

gas moving from a leaky stove to all corners of the room

Movement of BOTH molecules of water and food dye when the two are poured into the same container. In this
instance water is not moving across a semi permeable membrane and therefore it is not an example of osmosis.
Facilitated diffusion: Movement of larger molecules or ions, through carrier proteins or protein channels embedded in
the cell membrane, from a region where it is in high concentration to a region where it is in low concentration. Help is
provided by specific transport proteins. (i.e. Along or down a concentration gradient) .This is passive, not requiring
expenditure of ATP.
Examples:

Uptake of glucose by a red blood cell

Uptake of ADP into mitochondria
Osmosis: Net movement of free water molecules, across a semi permeable membrane, (MUST HAVE BOTH OF
THESE POINTS…AND ONE OF ) from:
……….a region of high free water concentration to a region of low free water concentration
OR
……..a region of low solute concentration to a region of high solute concentration
OR
…… from a dilute solution to a more concentrated solution
As a very specific example of diffusion, osmosis is always a passive process, requiring no expenditure of ATP.
Examples:

Uptake of water by root hair cells

Uptake of water by kidney tubule cells (following concentration gradient created by active uptake of glucose,
amino acids and salts)
Active Transport:
Movement of molecules or ions, through carrier proteins embedded in the cell membrane, from a region of relatively low
concentration to a region of relatively high concentration of the particular molecule or ion. (i.e. AGAINST a concentration
gradient). This process is, as the name suggests, active and thus requires the cells concerned to expend ATP (energy).
Examples:

Uptake of most mineral ions into the root hair cells from the soil solution

Uptake of glucose from the intestine into capillaries
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
Uptake of glucose and urea from the kidney tubule into capillaries
2. Draw the cell membrane and show how molecules pass across the membrane.
Outside of cell
Through protein
channels by
facilitated
diffusion
Tiny uncharged
particles through
small pores by
diffusion
Through carrier
proteins
by active
transport
By dissolving into
the phospholipidbilayer
Inside of cell
3. Explain the difference between aerobic and anaerobic respiration. Include products and number of molecules
of ATP produced in each case.
Both aerobic and anaerobic respiration involve the breakdown of organic compounds (usually glucose) to produce ATP.
The main difference between them is that aerobic respiration uses OXYGEN while anaerobic respiration does not use
OXYGEN. Aerobic respiration produces a lot more ATP than does anaerobic respiration and is therefore more efficient at
releasing stored energy. Aerobic respiration has a net yield of 36 ATP (molecules) in most body cells (while liver, heart
and kidneys are more efficient and yield 38 ATP) and anaerobic respiration yields only 2 ATP. (in anaerobic respiration
organic bi-products such as ethanol or lactic acid are formed that still contained stored energy. This energy can be
utilised at a later time) Products of aerobic respiration are carbon dioxide and water. Products of anaerobic respiration
in plants cells and fungal cells are ethanol and carbon dioxide, while in animal cells the product is lactic acid only. The
process of transferring the stored energy in organic compounds into the high energy bonds in ATP is not 100% efficient
About 60% of the energy is lost as heat.
A summary of the differences between the two:
Feature compared
Aerobic Respiration
Anaerobic Respiration
Reactants
Glucose and Oxygen
Glucose only
Products
Carbon dioxide and water
Animal cells: lactic acid
Plant and fungal cells: ethanol and CO2
Energy yield
36/38 ATP
2 ATP
Location of reactions
mitochondria
Cytosol
Relative time taken when
aerobic and anaerobic
process are compared
Longer (more enzyme driven steps
in complete breakdown of organic
compound)
Shorter (fewer enzyme driven steps in partial
breakdown of organic compound)
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Note: if you are asked to compare two things you must do the analysis and make the comparison yourself. Presenting the
assessor with a list of facts about two processes, and expecting them to analyse the data you have provided is not
enough.
4. State the chemical equations for photosynthesis and respiration BOTH in words and chemical symbols.
Photosynthesis:
Balanced Chemical equation
chlorophyll
6CO2
+
12H2O
C6H12O6
+
6O2
+
6H2O
light
Word equation
Carbon dioxide
+
water
chlorophyll
glucose
+
oxygen
+
water
light
OR
Balanced Chemical equation
chlorophyll
6CO2
+
6H2O
C6H12O6
+
6O2
light
Word equation
Carbon dioxide
+ water
chlorophyll
glucose
+
oxygen
light
Aerobic Respiration:
Balanced chemical equation
C6H12O6
+
6O
Mitochondrion
2
6CO2
+
6H2O
+
36/38ATP
enzymes
Word equation
Glucose
+
oxygen
Mitochondrion
carbon dioxide
+
water
+
energy
enzymes
5. Outline what water is needed for in plants and in animals?
Plants: reactant in photosynthesis, support: turgor of cells, to act as a solvent for biochemicals, transport of organic
compounds (sucrose in solution), control of stomatal aperture. (i.e. via turgidity of guard cells), transport of hormones,
Animals: temperature regulation (perspiration), to act as solvent for biochemicals, transportation (circulatory
fluid),lubrication(joints, sexual), maintenance(tears), digestion (saliva, digestive juices), moistening of membranes(mucus
in respiratory systems)
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6. List the nutrients needed by humans.
Macronutrients: Carbohydrates, proteins, lipids Micronutrients: vitamins and minerals
7. What is the function of enzymes AND relate structure to function.
Function: To catalyse (speed up the rate of) biological reactions that would otherwise proceed too slowly to meet the
needs of the organism. They function by lowering the activation energy required to get a reaction started.
Some enzymes are intracellular and operate inside of cells e.g. enzymes that catalyse the various steps of aerobic
respiration or photosynthesis
Others are extracellular and operate in compartments inside of the organism. e.g. digestive enzymes that function in
mouth, stomach or intestine.
ALL enzymes are 3 dimensional proteins. Enzymes are specific - each one will act on a specific substance called its
SUBSTRATE and will produce PRODUCTS. Each enzyme is suited to its function as a specific part of its structure (called
its ACTIVE SITE) will fit with a part of the substrate. They will fit together with almost lock and key precision. This close
association of enzyme and substrate/s somehow facilitates the reaction.
8. How would you expect the alimentary canal of a dog and a koala to differ from that of a human? Why?
Different species of animals have different digestive systems, which are adapted to their unique requirements. The type of
food, method of food gathering and energy needs are some factors that influence the type of digestive system an animal
needs in order to survive. Herbivores have a more specialised digestive system than that of a carnivore because it is more
difficult to digest vegetation than meat. Complex polysaccharides require multi-step break down processes requiring
multiple enzymes.
The alimentary canal of a dog is about 6 times the length of its body, where as the alimentary canal of a human is only
about 5 times as long as the body. A Dog is a carnivores while a human is (usually) an omnivores. The structure of their
alimentary canal is quite similar. Both are structured to digest meat and fat. In addition to this humans also have a lot of
carbohydrates in their diet, which dogs do not. Dogs therefore have a longer small intestine than do humans because on
the high level of protein and fat in their diet. The variety in the human diet, compared to the dog’s diet, may explain the
relatively shorter alimentary canal of humans.
The alimentary canal of a koala is very long indeed; much longer than either the dog or human. It includes a very large
and expanded caecum and a long small intestine compared to a human.
The reason for this is the difference in diet. Koalas are herbivores, feeding exclusively on fibrous eucalyptus leaves, while
humans are usually omnivores. In order to chemically digest cellulose, a major component of eucalypt leaves, they must
house a large number of micro-organisms that are able to produce cellulase. These micro-organisms are located in their
caecum. To allow enough time for adequate absorption of products of digestion they need a very long small intestine.
For anyone interested in an extension read, a web site that compares human, wolf and sheep (omnivore, carnivore and
herbivore) in detail is:
http://www.second-opinions.co.uk/carn_herb_comparison.html
9. List the enzymes of the human digestive system and outline their function, location of production AND
location of action.
Enzyme
Function
Location of production
Location of action
Salivary amylase
Chemical break down of
cooked starch
Salivary glands
Mouth
pepsin
Chemical breakdown of
protein into polypeptides
Produced in the form of
pepsinogen inside the cells
Lumen of the stomach
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of the stomach
Lipase
(we will only consider
pancreatic lipase. NOT
gastric lipase or lingual
lipase)
proteases
amylases
nucleases
Chemical breakdown of
lipids into fatty acids and
glycerol
Pancreas
Lumen of Small intestine
Different proteases do
slightly different things.
Overall they chemically
breakdown proteins into
peptides, peptides into
smaller peptides and
eventually peptides into
amino acids
Pancreas (pancreatic
proteases e.g. trypsin)
Lumen of Small intestine
Small intestine: eg
dipeptidase
Lumen of Small intestine
To chemically bread down
carbohydrates into disaccharides and eventually
monosaccharides.
Pancreas: alpha- amylase
Lumen of Small intestine
Small intestine: eg maltase,
lactase, sucrase
Lumen of Small intestine
To chemically break down
DNA and RNA into
nucleotides
Pancreas
Lumen of Small intestine
10. What foods do you consume that do not require digestion?
Glucose lollies, glucose drinks, amino acids drinks; any food that is already in monomer/simples form can be directly
absorbed without digestion.
11. Explain the following:
a. Villi are an advantage in digestion
Villi are finger like projections located in the intestine. They don’t actually assist in digestion of food, however they do
assist in the absorption of the products of digestion. They are long and thin and thus provide a very large surface
area over which the products of digestion can be absorbed into capillaries or lacteals. This enables the products of
digestion to be quickly and efficiently taken up.(increased rate of absorption)
b. The stomach has a sphincter at each opening
This ensure that ingested food spends an adequate amount time in the stomach to ensure that ‘food’ passing into the
intestine is in a suitable physical and chemical form. The soupy mixture that passes into the duodenum from the
stomach is called CHYME. The pyloric sphincter at the base of the stomach relaxes letting small quantities of chyme
through. The cardiac sphincter (between the oesophagus and the stomach) prevents reflux of stomach contents into
the oesophagus. Stomach contents contain HCl which would damage the lining of the oesophagus if reflux occurred.
c. There are no amylases in the stomach
Each enzyme will maintain its 3 dimensional shape, and function optimally only within a specific pH range. If the pH
varies from too much from the optimum, then the enzyme will become denatured and it will no longer perform its
function. Amylases function optimally at a slightly alkaline pH(about 8). The pH of the stomach is 1-2 (due to the HCl
secreted by the gastric lining). At this pH amylases will become denatured and therefore loose their function……So
amylases are not secreted into the stomach.(any amylase present in the chewed food when it arrives in the stomach
will be quickly denatured)
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d. You can swallow while standing on your head
This is possible because food is moved towards the stomach from the mouth, not by gravity but by peristalsis (wave
like muscular contractions along the oesophagus). Muscular contractions force food upward towards the stomach
when you are standing on your head.
e. The concentration of glucose in the small intestine is lower than in the capillaries of the villi.
This is because ATP is expended by the cells of the villi to actively take up glucose against its concentration gradient,
ensuring the maximum absorption of glucose. (Also keep in mind that solute refers to the amount of solute per unit of
volume of solution and there is a much greater volume of solution in the intestine compare to the capillary)
f.
The stomach has both mechanical and chemical digestion
Mechanical digestion involves breaking large pieces of food into smaller pieces. Contraction and relaxation of the
muscular layers of the stomach wall churn food and mix it with the gastric juices. This action helps to break food into
smaller bits, helping to increase the surface area available for the action of enzymes.
At the same time glandular cells of the stomach lining secrete pepsinogen which becomes the enzyme pepsin. This
enzyme catalyses the chemical breakdown of proteins.
g. Fibre is needed in the diet
Fibre is needed in the diet because it is not digested by humans and adds bulk to the ingest food mass. It assists with
the movement of the food along the alimentary canal, decreasing transit time and rectal storage time. It reduces the
chance of contracting bowel cancer and enables stools to be passed more easily.
12. Describe the digestion of fried chips by a human
Chips are mechanically broken into smaller pieces in the mouth by the action of the teeth, assisted by the
tongue(increasing the surface area exposed to salivary enzymes) and mixed with saliva. An amylase(ptyalin) in the
saliva begins the digestion of starch.
In the stomach the soupy chip mixture will be mixed with chyme but chemical digestion is halted.
In the duodenum bile salts will emulsify the lipids present in the chips and pancreatic lipase will break lipids into
glycerol and fatty acids.(these are absorbed across the wall of the villus into the lacteal)
13. Describe the differences between ventilation (inhalation and exhalation), gaseous exchange and cellular
respiration.
These three processes are very different to each other. In very simple terms; ventilation involves getting air into and out of
the organism, gas exchange involves getting oxygen into the internal environment of the body and carbon dioxide out, and
respiration is a cellular process(occurs inside individual cells) whereby energy is release from organic compounds.
In a little more depth:



Ventilation is the moving of air into and out of the lungs (or other respiratory organs in other organisms). In
humans inhalation is achieved decreasing the air pressure in the thoracic cavity (relative to the external
atmospheric pressure) by flattening the diaphragm (contraction of diaphragm muscle) and raising the rib
cage(contraction of intercostal muscles). Exhalation is achieved by increasing the air pressure in the thoracic
cavity (relative to the external atmospheric pressure) by raising the diaphragm(relaxing and lengthening the
diaphragm muscles) and lowering the rib cage(relaxing the intercostal muscles).
Gas exchange involves the diffusion of gases across a respiratory surface. Specifically it involves the diffusion of
oxygen across the respiratory surface into the circulatory fluid and the diffusion of carbon dioxide from the
circulatory fluid into the alveoli.
Cellular respiration refers to a cellular process whereby glucose (or another organic molecule) is broken down in a
series of steps to release energy. ( packaged as ATP)
14. At what times of the day would you expect the stomata of a plant to open and close?
Stomata begin to open when the carbon dioxide level in the guard cells begin to fall. (which causes influx of K+ ions into
guards cell, uptake of water into these cells via osmosis and the guard cells to become turgid and buckle outwards,
creating the stomatal opening)
-6-
Carbon dioxide levels begin to fall in guard cells as photosynthesis commences in the morning. So in most plants
stomata begin to open in the morning (say 7am)and the size of the opening increases until it is at its maximum in the
middle of the day.(say 1pm) Stomata then progressively decrease in size to close by early evening.(6-7pm) The precise
times vary with species and environment. Some plants have inverted stomatal rhythms to equip them for very dry, hot
conditions.
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15. Sketch a stoma and explain how the guard cells function.
One stoma is composed of two guard cell surrounding a central pore. When water moves into the guard cells via
osmosis, the two guard cells become turgid and the stoma opens. (Due to the specialized structure of the guard cells, as
they fill with water the outer wall of the guard cells stretch more than the inner cell walls and the cells ”buckle”. This
causes a pore or space to form between the two guard cells: the stoma is open). When water moves out of the guard
cells via osmosis, the two guard cells become flaccid and the stoma closes.
16. Explain why lettuce leaves wilt after the lettuce is picked
After the lettuce has been picked (depending on the environment the lettuce is in wilting may take differing
amounts of time to occur) the rate of evaporative water loss via stomata, exceeds the rate of water uptake(since
the picked lettuce will have no source of water; assuming a human hasn’t provided a source of water that is!) This
means that cells will become flaccid and the lettuce leaves will wilt.
17. Sketch and label a cross-section of a leaf AND relate structure to function.
Xylem
cuticle
Upper epidermis
Palisade
cells
chloroplasts
Vascular bundle
Spongy
cells
stomate
stomate
Guard
cell
epidermis
phloem
Liquid
water
Water
Carbon dioxide
oxygen
-8-
Structure suits it to its function (to produce organic materials for the plant from inorganic materials) in many ways.
Examples include:
a. Cells with largest numbers of chloroplasts are located at the top of the leaf, where most sunlight falls. This
maximises exposure of plant/chloroplasts to sunlight, a requirement in the process of photosynthesis.
b. Leaf is blade shaped: thin and flat. The flat shape suits it to its function as a large area is able to directly
absorb radiant energy from the sun. As it is thin gases do not need to travel far b/w the cells and the
external environment
c.
Presence of xylem: allows the water required for photosynthesis to be transported to the palisade
mesophyll cells and spongy mesophyll cells.
d. Presence of phloem: allows the products of photosynthesis to be transported for use by non
photosynthetic parts of the plant or transported for storage.
e. Stomata: Open to allow uptake of carbon dioxide from the external environment. They can also close to
reduce water loss when water loss begins to exceed water uptake.
f.
Presence of air spaces facilitates faster diffusion of gases around the leaf. (diffusion occurs at a faster
rate in a gas than in a liquid)
18. Outline the features of alveoli that assist in diffusion of gases.

The wall of the alveolus is very thin (only one cell thick). This enables gases to pass quickly across.

The alveolus wall is moist, enabling gases to dissolve into a liquid and thus pass across the alveolus wall.

Alveolus is surrounded by capillaries. Continual movement of blood through the capillary helps maintain a
concentration gradient of oxygen and carbon dioxide between the alveolus and blood, ensuring that diffusion
can continue.

Alveoli are tiny and numerous and collectively provide a huge surface area over to ensure that exchange
occurs quickly enough to meet the metabolic needs of the organism.
19. Ringbarking destroys phloem. What effect does this have on plants?
Ringbarking will result in the eventual death of the plant. Phloem transports carbohydrates in the form of sucrose (as
well as other organic compounds) from the leaves of the plant (where it was formed as glucose during
photosynthesis) to other areas of the plant including the roots via a process called translocation. Root systems of
plants are extensive. They anchor the plant to the ground and absorb water and mineral ions from the soil solution.
Like all living cells they require energy (ATP) to live. They need to carry out cellular respiration to produce ATP for
use in all cell processes including active uptake of mineral ions form the soil. Roots are not photosynthetic. They rely
on the supply of organic compounds via the phloem, and if these aren’t being delivered, cell processes in the root
cells will cease and the roots will die. Active uptake of mineral ions will cease, and this will greatly affect water uptake
by osmosis. These effects will lead to a lack of photosynthesis in the leaves (due to insufficient supply the reactants
and mineral ions) and will lead to the death of the entire plant.
In summary:
Plant will die
Roots cannot make their own glucose
Sucrose cannot be translocated to roots therefore once energy stores in the roots are depleted, the root cells have no
source of glucose for use in cellular respiration.
Thus they cannot produce the ATP required for active process in the roots cells such as
-9-

Active uptake of ions

Cell division

Cell maintenance
Photosynthesis would be reduced due to diminished resources and roots would not be able to perform their role. The
plant would eventually die.
20. Describe AND contrast translocation and transpiration.
Translocation involves the transport of dissolved substances including organic compounds (especially sucrose) and
ions (and water since materials are transported in solution) in the phloem of a plant. Sucrose is generally transported
from the leaves downward to the roots. It moves from SOURCE to SINK. However since translocation involves active
processes the direction of the movement of materials can be controlled. (ie. Up down or sideways)(for example in the
winter time stores of carbohydrate in the roots can be mobilized and the root before the SOURCE. Starch can be
converted to sucrose for transport to other parts of the plant requiring glucose for use in respiration)
Transpiration is the loss of water from the surface of a plant, particularly (but not exclusively) through the stomata.
The transport of water and mineral ions through a plant from root to leaves is primarily the result of transpiration.
The transpiration stream involves the transport of water and mineral ions through a plant from roots to leaves,
caused by transpiration.
Translocation is the transport of organic material, while transpiration is an evaporative process. ( while it results in
water moving upwards in the xylem, transpiration is not actually defined as the transportation of water.)
They differ from each other in the following ways:
Difference
The materials involved
Takes place where?
Translocation
Movement of organic compounds
(especially sucrose) and mineral ions
In the phloem
Active or passive
Active: ATP required
Transpiration
Evaporation of water
At the surface of the plant. Mostly via
stomata of the leaves. Leads to
water being drawn up the xylem
ATP not required. Relies on heat
energy mostly provided by the sun
21. Make a table comparing Xylem and Phloem in terms of
i.
ii.
iii.
iv.
The structure of the cells
The properties of the cells
The substances that are transported
The directions in which they are transported
The structure of the cells
The properties of the cells
Xylem
Xylem vessels
Elongated cells placed end on end
to form a continuous column.
Wholes(pits) in the side cell walls of
the cells)
Cell walls impregnated with lignin
Tracheids
Large tapering cells with many pits
in their lignified walls
Phloem
Sieve tube cells sit end on in a linear
arrangement
Sieve tube cells are in close
association with companion cell
Sieve plate and the base of each cell
is perforated
Dead, no cellular components
remain inside the cell wall
Living cells
Sieve tube cells lack a nucleus and
most organelles
- 10 -
The substances that are transported
Water and mineral ions
The directions in which they are
transported
Upwards from roots to leaves
Companion cells have a prominent
nucleus
Sucrose (in solution so water is also
present), some other compounds in
small amounts like amino acids and
mineral ions
Up, down and sideways
22. Make a table listing how flowering plants and mammals:
i. Obtain nutrients they require
ii. Store carbohydrates, protein and lipids
Obtain nutrients they require
Flowering Plants
Mammals
Obtain ions from soil solutions;
diffusion or active uptake across
roots and then transported to cells
in Xylem sap
Nutrients are ingested in the foods
they consume
Make glucose via photosynthesis
and all other organic compounds
are synthesised from the product of
photosynthesis
Store:
Carbohydrates
Usually as starch, although some
store carbs as sucrose(eg. sugar
cane)
Proteins
Stores of protein in legumes
Lipids
Oils in seeds
Short term: glycogen
Long term: converted to fat for
storage
Mammals don’t store protein,
however many structural
components of the body are made
of protein and these can be broken
down if the body requires the amino
acids within
Fat in adipose tissue
23. Draw a diagram showing the path of a water molecule from the soil though the plant.
- 11 -
24. Describe the structure AND related function of arteries, veins and capillaries.
Blood Vessel
Arteries
capillaries
veins
Structure
Thick elastic wall, small lumen, absence of one
way valves
Very narrow blood vessels (red blood cells just
fit through), wall very thin (one cell thick)
Compared to arteries they have a thinner less
elastic wall and a larger lumen. They also
have one-way valves.
Function
To transport blood under high pressure, away
from the heart towards body organs/tissue
To provide a large surface area for exchange
of materials between blood and tissue.
To transport blood back towards the heart.
25. List and describe the 4 components of blood. What is the function of each?
Component
Erythrocytes (red blood cells)
Leukocytes (white blood cells)
Platelets
Plasma
Function
MAIN FUNCTION: Transport of oxygen
Also transports some carbon dioxide
Defence against disease causing organism
Engulfment of pathogens
Production of antibodies
Destruction of abnormal or virally infected cells
To assist in the clotting of blood
Suspends blood cells and platelets
To carry nutrients, bicarbonate, dissolved gases, waste, hormones etc.
- 12 -
26. Draw a diagram of the heart showing the chambers, vessels and valves. Indicate the direction of blood
flow.
Note:
Right atrio ventricular valve is called the tricuspid valve
Left atrio ventricular valve is called the bicuspid valve
27. Structurally how does the left ventricle of the heart compare with the right ventricle of the heart.
The left ventricle of the heart has a thicker wall and smaller lumen than the right side of the heart. (this is to
provide the degree of force need to move blood all around the body, as opposed to the smaller force that is
required from the right ventricle which only needs to move blood a short distance to the lungs)
28. Veins have one-way valves. Why is this?
Veins carry blood under low pressure. Movement of blood in veins relies on pressure from contraction of nearby
skeletal muscles and ensuring that this cause blood to move forward towards the heart, but one way valves snapping
shut to prevent backflow in the opposite direction. Without these valves blood would be squeezed in both directions
simultaneously all along veins, and blood would not be successfully and efficiently returned to the heart.
29. Explain why your feet might swell when you are sitting still on a long plane flight. Why does exercise
help with this problem.
Accumulation of tissue fluid in the tissues of the feet are responsible for the swelling to feet experience on a long
plane journey. Tissue fluid accumulates due to inefficient functioning of the lymphatic vessels which usually pick
up excess tissue fluid and return it into circulation. Lymphatic vessels rely on movement of skeletal muscles to
transport the lymph within them up towards the vena cava. If someone is sitting still, skeletal muscles will not be
placing pressure on the fluid with the lymphatic vessels to moving it along. Exercise makes skeletal muscles
contract and push on the walls of the lymphatic vessels, thus moving lymph along and helping to reduce the
problem of swell due to tissue fluid accumulation.
30. Define excretion and metabolic waste.
Metabolic waste refers to waste produced as a result of metabolic processes within cells.(metabolic process are all
of the breakdown and build up processes that occur in side of body cells. e.g. cellular respiration, breakdown of amino
acids. etc.
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Examples of metabolic waste include: CO2, NH3 (ammonia), urea, heat uric acid
Excretion is the removal of metabolic waste from the body. (NOT the elimination of undigested food material from the
31. Name and describe all the vessels and chambers of the heart that a red blood cell passes through from
the time it picks up oxygen in an alveolus, passing into the right forefinger where it releases oxygen and
picks up CO2 which it then releases in an alveolus.
Names only:
Beginning: lung capillaries, pulmonary vein, left atrium, (past bicuspid valve), left ventricle, past semilunar valve,
aorta, subclavical artery, capillaries in the finger, subclavical vein, vena cava, right atrium, (past tricuspid valve), right
ventricle, past semilunar valve), pulmonary artery, capillaries in the lung. End
Brief descriptions:
Pulmonary vein: vein carries oxygen rich blood from lungs to heart.
Left atrium: small upper chamber on the left side of the heart. It receives oxygen rich blood from the pulmonary vein
and transfers it to the left ventricle.
Left ventricle: Larger lower heart chamber on the left side of the heart. It has quite a small lumen, lots of striations
and the thickest muscular wall of the four heart chambers. Its role is to pump blood to the body (other than the lungs)
Aorta: Major artery of the body. Carries blood directly from heart to the other main arteries of the body. It has
extremely thick and elastic wall, as it must withstand the force of blood under high pressure surging into it directly from
the left ventricle of the heart.
Suclavical artery: artery leading from aorta to arm
Subclavical vein: vein leading from arm to vena cava
Vena cava: main vein of the body. It carries blood directly to right atrium
Right atrium: small upper chamber on the right side of the heart. It receives blood from the vena cava and transfers it
to right ventricle.
Right ventricle: contracts and forces blood into the pulmonary artery. The wall of the right ventricle is thicker than that
of the right atrium, but thinner than that of the left ventricle.
Pulmonary artery: Carries oxygen poor blood to the lung.
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32. A cheese sandwich contains fibre, fat, protein, carbohydrate (sucrose and starch) and water. What are the
listed components broken into? Describe the passage of the cheese sandwich as it moves through the
digestive tract.
In a human:
Component
Broken into?
Fibre
mostly undigested: remains as fibre
Fat
glycerol and fatty acids
protein
amino acids
Carbohydrates:
Sucrose
glucose and fructose
starch
glucose
water
Not digested: remains as water
In the mouth: The sandwich is chewed by the teeth and is broken into pieces. The tongue rolls the pieces around and
mixes them up with saliva. Chemical digestion of starch begin with amylase acting on the starch in the bread. The
food is rolled into a bolus and pushed to the back of the throat. It is swallowed.
Food is moved by peristalsis (wave like contractions) to the stomach. In the stomach the food is churned and further
mechanically broken down by the contraction of the muscular layers of the stomach. HCl and pepsin are released.
Pepsin begins to chemically break down protein in the sandwich.
When in the consistency of chyme, food is release into the small intestine via the pyloric sphincter. Secretions enter
the duodenum from the pancreatic duct. One of these secretions is bile (produced by the liver and stored in the gall
bladder). The other material produced in and secreted from the pancreas include pancreatic juice containing enzymes
and bicarbonate ions. The bicarbonate works to neutralize the acidic chyme, to create a suitable environment for
pancreatic and intestinal enzymes to function in. Bile emulsifies the fat component of the sandwich, and lipases
chemically digest this. Proteases continue to chemically digest the protein component of the sandwich. Carbohydrate
digestion also continues here. Peptides are broken down to their constituent amino acids here. Absorption of simple
nutrients across the villi begins and it will continue along the ileum. Amino acids and glucose are actively taken up
and pass into capillaries, glycerol and fatty acids move into the lacteals. Most water is absorbed in the small intestine.
Most nutrients have been absorbed. Fibre remains. As the fibre passes along the large intestine more water is
absorbed and the “waste” material becomes dryer and more compact.
Waste is stored in the rectum and eliminated via the anus.
33. Describe how the random movement of molecules results in an even distribution of molecules throughout
a system?
Molecules are in a constant state of random movement. Molecules are continually colliding with other molecules.
When this happens molecules rebound and move off in different directions. The more molecules present in particular
area the more frequently collisions will occur, and the more the molecules will spread. Eventually this will result in an
even spread of molecules over the space available. When molecules are evenly spread they will still move and
collide, but at this point there will be an even amount of collision and rebounding in all directions. This situation is
called dynamic equilibrium.
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34. Define the terms hypotonic, hypertonic and isotonic and explain what would happen to a cell if it were
placed in each of these solutions.
An isotonic solution has the relative same number (concentration) of solute particles as the solution to
which it is compared.
A hypotonic solution has a lesser relative number (concentration) of solute particles (higher number of
water particles) than the solution to which it is compared.
A hypertonic solution has a higher relative number (concentration) of solute particles (lesser number of water
particles) that the solution to which it is compared.
Effect on cells of being place in different types of solutions
Cell type
Isotonic solution
Hypotonic solution
Hypertonic solution
Animal cells
Nothing appears to happen.
This is because there is no
net uptake or loss of water
Net uptake of water into the
cell from the solution. Cells
will swell. If the
concentration gradient is
large enough, the cell may
take up so much water that
it could burst
Net loss of water from the
cell to the solution. Cell will
“shrink” as the cell volume
decreases. Cells crenate.
Plant cells
Nothing appears to happen.
This is because there is no
net uptake or loss of water
Net uptake of water. Cell
will become very turgid. It
will not burst as the cell wall
will withstand the internal
pressure, as water moves
into the cell
Net loss of water form the
cell vacuole and cytosol. As
the cell volume decreases
the membrane pull away
from the rigid cell wall. The
cell becomes plasmolysed.
35. In simple terms, describe what is meant by the terms turgid, plasmolysis and flaccid.
Turgid: Cell is distended with water and very taut. The cell membrane is pressing hard up against the cell wall.
Plasmolysis: Process whereby the cell membrane of a plant cell pulls away from the cell wall, as the volume of the
cell decrease as a result of water loss. A distinct “gap” is evident between the membrane and the wall of the cell.
Flaccid: The cell is no longer taut, but limp due to less water pressure inside. The cell membrane is not pressing
hard up against the cell wall
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36. For the organelles listed below draw up a table to: describe its structure; give a major function; indicate
whether it is surrounded by a single membrane, a double membrane or no membrane; and state whether
it is found in plant, animal or bacterial cells: nucleus, endoplasmic reticulum, Golgi apparatus, ribosome,
chloroplast, mitochondria.
Organelle and structure
Function
Membrane?
Found in plant cells,
animal cells or bacterial
cells.
Nucleus:
To control ALL the activities
of the cell (by determining
what proteins are
manufactured)
YES
Plant cells and animal cells
A double membrane
(except mature red blood
cells, sieve tube elements
and xylem tissue)
Internal transport of
materials
It is composed of
membranes rather than
being surrounded by
membranes
Plant cells and animal cells
To modify and package
material made inside of the
cell into vesicles for external
transport.(secretion)
YES
Plant cells and Animal cells
Site of protein synthesis:
NO
Plant cells, Animal cells and
Bacterial Cells
Site of photosynthesis
YES
Plant cells
Organic compounds(usually
glucose) is produce here
from inorganic compounds
(water and carbon dioxide)
A double membrane
Site of aerobic respiration
YES
It is here that organic
compounds, usually glucose
is broken down to release
ATP.
A double membrane
Large, surrounded by
nuclear membrane, contains
the genetic material
(chromosomes)
Endoplasmic Reticulum
A network of channels
formed from flattened
membranes
Golgi apparatus
Stacked membranous sac
with vesicles budding off
from the sides
ribosomes
i.e. it is here that amino
acids are linked together to
form polypeptides.
chloroplasts
mitochondria
Plant cells and Animal cells
Cell’s powerhouse.
Note: Bacteria are prokaryotic: They have a cell membrane, a cell wall, a cytosol and ribosomes. Cyanobacteria have
chlorophyll located in a structure called a thylakoid.
37. Explain the importance of membranes and compartmentalization to cells.
Keeps high levels of the right enzymes in the right places for particular reactions to occur.
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38. Explain why cells are microscopic, i.e. less than 100 micrometers in diameter.
So that they have a very large surface area to volume ratio to enable efficient exchange across the cell surface to
sustain the needs of the cell.
39. Describe the similarities in structure of mitochondria and chloroplasts. How are these similarities related
to the functions of theses organelles?
Similarities between mitochondria and chloroplasts:

They both contain their own DNA.

They are both surrounded by a double membrane.

Both have many internal membranes with a large surface area(grana in chloroplast and cristae in
mitochondria.)

They are similar in size.

They both contain many enzymes.
Don’t worry too much about relating similarities in the structure of mitochondria of chloroplasts to their functions. This
is a bit complex:
Both of these organelles are sites of a complex metabolic process, involving many steps, each catalysed by a
different enzyme. The outer membrane separates these enzymes and processes from the rest of the cytoplasm.
Some parts of each metabolic process require membranes to embed carrier molecules or enzymes in. Each has a
large surface area of internal membrane to facilitate this.
40. List four differences between prokaryotic and eukaryotic cells. Which of these were the first cells on
earth.
In general terms prokaryotic cells ( e.g. bacteria) are much simpler in structure than are eukaryotic cells (e.g. cells of
animals, plants, fungi):

Prokaryotic cells are much smaller that eukaryotic cells.

Prokaryotic cells lack a membrane bound nucleus while eukaryotic cells have a membrane bound nucleus.

Prokaryotic cells lack all other organelles that are surrounded by a membrane, which eukaryotic cells have
these.

The process of cell division in Prokaryotic cells is binary fission while in eukaryotic it is mitosis.

Prokaryotes have their DNA in a circular chromosome while in eukaryotic cells the DNA is in a linear
chromosome.
Prokaryotes, with their extremely simple structure in comparison to eukaryotes, were the first cells to evolve.
41. Outline the similarities and differences of plant and animal cells.
Similarities: Both have a cell membrane, cytosol, nucleus, ribosomes, golgi bodies, endoplasmic reticula and
mitochondria. Both cell types are microscopic.
Differences:
Plants cells also have a cellulose cell wall and large permanent vacuoles, which animal cells lack. Plant cells may
also have plastids such as chloroplasts, which animal cells do not have. Plant cells are generally a lot larger than
animal cells.
Animal cells have centrioles, which higher plants lack.
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42. In the parent cell at Metaphase there are 46 double stranded chromosomes. A double stranded chromosome is
composed of two chromatids joined together at the centromere. During anaphase the chromatids separate and
now as single stranded chromosomes move to opposite poles and into different daughter cells. So each daughter
cell inherits one strand of each double stranded chromosome in the parent cell.
So at metaphase the parent cells has 46 double stranded chromosomes (92 molecules of DNA in total. Each d/s
chromosome is made of 2 molecules of DNA) and when each daughter cell is initially formed each has 46 single stranded
chromosomes (46 molecules of DNA in total. Each s/s chromosome is made of one molecules of DNA)
43. Describe the events in each of the following phases of the cell cycle; G1, S, G2, and M.
G1 Growth. Cell increases in size and synthesizes new proteins and organelles.
S Replication of DNA. An exact copy of each molecule of DNA is synthesised and this enable D/S chromosomes to be
formed.
G2 Preparation for division (eg spindle assembly begins)
M. Mitotic Phase of the Cell Cycle. This includes MITOSIS AND CYTOKINESIS.
Mitosis is Nuclear division. This is divided into 4 main stages as follows
a. Prophase: nuclear membrane breaks down, chromosomes condense
b. Metaphase: chromosomes are pulled to the equator
c.
Anaphase: Chromatids separate and as single stranded chromosomes move to opposite poles of the cell.
d. Telophase: new nuclear membranes form around each new nucleus, chromsomes decondense.
Cytokinesis: cytoplasm divides into two.
(Often cytokinesis overlaps with mitosis)
44. Explain the difference between a chromatid and a chromosome; use a diagram with your explanation.
A chromosome is a structure formed from DNA and packaging proteins. (seen in a cell during cell division) A
chromosome can be single stranded(made of one molecules of DNA only) or Double stranded (made of two
identical molecules of DNA joined by a centromere) The term chromatid is used to describe part of a double
stranded chromosome. To be more precise it is one of two strands making up a double stranded chromosome.
45. Explain how does mitosis ensures that each daughter cell has the same genetic makeup as the parent
cell?
Each double stranded chromosome is composed of two identical molecules of DNA. At anaphase one of each
identical molecule of the d.s chromosome is drawn to each pole of the parent cell and become part of each
daughter cell. Thus each daughter cell get one of each molecule of DNA of the parent cell and so will be
genetically identical to the parent cell and to each other.
46. List the parts of the compound light microscope and their functions.
Most important parts:
Part
Function
ocular
magnification
objective
Magnification and resolution
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condenser
To converge light direct through it onto the specimen
diaphragm
To adjust the amount of light passing through the
specimen to adjust the contrast of the specimen
Focussing knobs
To sharpen the image
47. Microscope Calculations: be familiar with the terms total magnification, field of view, actual size, scale
Total Magnification: power of ocular (e.g. x10) multiplied by power of objective lens (e.g. x40). 10x 40=100
Total magnification X 400
Field of view: The circular area viewed when looking down the microscope.
Diameter of Field: The distance from one side of the field of view to the other, passing through the centre.
Magnification
Approximate diameter of field
Low power (X100)
1800 micrometers (microns) (µm)
High power(X400)
450 micrometers
Actual size: find how many times the length of the organism will fit across the field of view. Divide the diameter of the
field of view by this figure to determine the length of the organism.
e.g. X100 magnification
diameter of field = 1800 µm
2 organisms fit across field.
Length of organism: 1800/2= 900µm
Scale: My drawing on this organism is 12 cm long:
900/ 12= 75
So 1cm in my diagram is equivalent to 75µm in real life
I would rule a 1 cm line near the diagram and write 75 µm underneath to indicate that 1cm represents 75µm
48. What is the difference between mono/di/polysaccharides? Give examples.
Monosaccharide: a single sugar unit eg. Glucose, galactose, fructose
Disaccharide: Carbohydrate molecule composed of two monosaccharides chemically bonded. e.g. sucrose, maltose,
lactose.
Polysaccharide: Carbohydrate formed from many monosaccharides chemically bonded. e.g. chitin, cellulose, starch,
glycogen
actions are called ANABOLIC reactions
49. List the building blocks for: a) glycogen b) cellulose c) proteins d) phospholipids e) DNA.
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i. monosaccharides
ii. monosaccharides
iii. amino acids
iv. fatty acids and phosphorus
v. nucleotides
50. State which macronutrient is used for: a) primary energy source b) long-term energy storage c) genetic
material d) cell membrane components
b) carbohydrate (specifically glucose)
b) lipid (fat)
c) nucleic acid
d) lipid (specifically phospholipid) and protein
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