WORKBOOK ANSWERS
AQA GCSE Biology
 Paper 1: Cell biology; Organisation;
Infection and response; Bioenergetics
 Paper 2: Homeostasis and response;
Inheritance, variation and evolution;
Ecology
This Answers document provides suggestions for some of the possible answers that might be
given for the questions asked in the Workbook. They are not exhaustive and other answers
may be acceptable, but they are intended as a guide to give teachers and students feedback.
Paper 1
Cell biology
1 a
b
2 a
They have a nucleus. (1)
The site of protein synthesis (1) [2 marks]
A — cell membrane (1); C — chloroplast (1); E — mitochondria (1)
b
Any two from: C, G and F (2)
c
Any two from: C, D, E and F (2) [7 marks]
3 a
×400 (1)
b
Higher magnification and higher resolution (1) have allowed us to see structures not
previously seen/have allowed us to see structures in greater detail (than previously seen) (1).
c
i
Unit
Symbol
Number per
metre in
standard
form
1
© Dan Foulder 2018
Education
Hodder
Millimetre (1)
mm (1)
1 × 106 (1)
ii
45 (mm) × 1000 = 45 000 µm (1)
45 000/600 (1)
= 75 µm (1) [9 marks]
It is very important that you show your working out when carrying out a calculation. If you make a
mistake, and you do not show your working out, you will get no marks even if the mistake is at the final
stage of the calculation. Normally, the correct answer without working out will get full marks.
4 a
The cell grows and increases the number of subcellular structures. (1) The DNA replicates to
form two copies of each chromosome. (1)
b
Growth/replace worn out cells/repair damaged parts of the body (1)
[3 marks]
5 a
Embryos — can divide (and subsequently differentiate) to produce most types of human cell.
(1). Adult humans — can form cells of the same general type. (1)
b
Can transmit viruses. (1) Some people are religiously opposed to the use of stem cells in
treating humans. (1)
c
i
Meristem (1)
ii
Rare plants can be protected from extinction. (1) Desirable qualities, e.g. disease
resistance, can be developed in crop plants. (1)
[7 marks]
i
Diffusion is the movement of particles in a gas or in solution from an area of high
concentration to an area of low concentration. (1)
ii
Concentration gradient (1); temperature (1); surface area across which diffusion takes
place (1)
i
As animals increase in size the surface area-to-volume ratio decreases. (1) The
specialised exchange surfaces increase the area across which substances can diffuse.
(1)
ii
Gills (1)
6 a
b
7 a
[7 marks]
Cell membrane (1)
b
The volume of liquid inside the Visking tube will decrease/the Visking tube will become less
firm (1) because the solution outside the Visking tubing is more concentrated than the solution
inside the Visking tubing (1). Water moves out of the Visking tubing into the beaker by osmosis. (1)
In many questions there is no exact ‘correct’ answer. In this question you are asked to suggest how the
appearance of the Visking tubing will change after 24 hours; appearance can mean many things, e.g. the
2
fact that the tubing is smaller, less firm, less rigid. There will usually be a range of acceptable answers
for at least some of the marking points in ‘suggest’ type questions.
c
There was probably a leak where the tubing was tied (1), allowing substances to diffuse in
and out of the tubing (1).
[6 marks]
8 a
Transports substances down the concentration
gradient
Requires energy from respiration
Diffusion
Osmosis
 (1)
 (1)
Active
transport
 (1)
b
Plants — root hairs absorbing mineral ions. (1) Humans — sugars being absorbed from the
gut into the bloodstream. (1) [5 marks]
Exam-style questions
9 a
i
Site of aerobic respiration/release of energy (1)
ii
(As a result of respiration) the carbon dioxide is at a higher concentration inside the cell
than outside. (1)
iii Any two from:
b

cytoplasm

cell membrane

cell wall (if it is a plant cell) (2)
60 mm/150 µm (1)
60 000/150 (1)
= 400 (1)
c
i
Myelin sheath correctly labelled (1)
ii
Long (axon) length (1); many ends to form synapses with other nerve cells (1).
marks]
i
The inoculating loop should not have been placed immediately into the culture bottle (it
should have been allowed to cool first to prevent the bacteria being killed). (1)
[10
10 a
The Petri dish lid should not have been placed on the bench (it should have only been
partially opened to restrict the possibility of contamination). (1)
The loop and culture bottle should not have been placed in the sink for washing (they
should have been autoclaved or disposed of as per the teacher’s instructions). (1)
3
ii
If higher, it could allow pathogenic microorganisms to grow. (1)
If lower, the microorganisms would not grow/would take a long time to grow. (1)
iii Prevents condensation liquids falling from Petri dish lid onto the culture (1) and killing
microorganisms (1).
b
i
Any four from:

largest clear area around antibiotic C

smaller clear areas around B and D

no clear area around A

antibiotic C is most effective at stopping growth/killing bacteria

B and D have a reduced but similar effect

A has no effect on bacterial growth [4]
In many questions you are asked to describe and explain in an answer. Describe means answering ‘what’
and explain means answering ‘why’.
ii
radius = 10 mm (1)
3.14 × 100 (1)
= 314 (1)
[14 marks]
11 a
i
(−1/61) × 100 (1)
= −1.6 (1)
ii
0.6 mol dm−3 (1)
i
0.83 to 0.85 (1)
ii
The sweet potato cells are more concentrated than the potato. (1) More water enters the
cells by osmosis because the concentration gradient is greater/therefore water will enter
the sweet potato cells even when in relatively high sugar concentations. (1)
b
iii Any two from:
c

length of time cylinders were in solutions

age of potato and sweet potato

thickness of cylinders (2)
Any two from:

cylinders can have different/irregular thicknesses
4

ends may not be even

impossible to measure length as accurately as mass (e.g. mass can be measured to two
decimal points in a school lab) (2)
[10 marks]
12

Put solution A into Visking tubing and tie the ends tightly. (1)

Dry the surface of the Visking tubing and weigh. (1)

Place the Visking tubing into a beaker containing solution B. (1)

After a few hours remove the Visking tubing from the beaker, dry and re-weigh. (1)

If the Visking tubing gained in mass then it contained 0.4 mol dm −3 sugar (as water had
moved by osmosis from the 0.1 mol dm −3 sugar to the 0.4 mol dm−3 sugar)/if it lost mass then
it contained the 0.1 mol dm−3 sugar (as water had moved by osmosis out of the Visking
tubing). (1)
[5 marks]
Obviously this could have been done the other way around, with solution B in the Visking tubing and
solution A in the beaker. Another way this could be done – e.g. use two pieces of Visking tubing, each
containing one of the two different sugar solutions and place each in water. The Visking tubing that
contained the more concentrated sugar would be the one that reached the higher mass.
Organisation
1
Level of
organisation
Tissue (1)
Description
Series of organs that work together to carry out the same general function
(1)
Organ (1)
[3 marks]
2 a
Fatty acids (1); glycerol (1)
b
Food tested
Reagent
Iodine
Initial colour
Final colour
Blue-black
Biuret
Glucose
Heating required
No
Blue
One mark for each correct complete row [3] [5 marks]
In the bottom row it is important you answer glucose rather than carbohydrate because the iodine test is
for starch, which is also a carbohydrate.
3 a
Protein → amino acids (1)
b
The active sites of protease enzymes are an exact fit to protein molecules (1), but they are
not the right shape to link with starch molecules (1). [3 marks]
5
4 a
Red blood cell — transports oxygen (1)
White blood cell — defence against disease (1)
b
i
Right ventricle (1)
ii
Pulmonary vein correctly labelled on the diagram (1)
iii Valves to stop the blood flowing from the ventricle into the atrium (when the heart
beats)/to stop the blood flowing backwards in the heart (when the heart beats). (1)
c
The ventricles pump blood all around the body or to the lungs. (1) The atria only pump blood
into the ventricles. (1)
[7 marks]
As there were 2 marks for part c you should be able to work out that you need to answer more than just
stating that the ventricles pump blood further than the atria. Also, it is important to make reference to
both the ventricles and the atria.
5 a
b
2–3–4–1 (all correct = 2; any two in correct sequence = 1)
Statins — reduce blood cholesterol levels (1). Stents — keep (coronary) arteries open (1).
[4 marks]
6 Individual — can damage the liver and/or the brain (1). A local community — can lead to
violence/antisocial behaviour/relationship problems/problems at school or work. (1)
[2 marks]
Alcohol can damage an individual in many ways, not just by harming the liver or the brain. However, as
the liver and the brain are listed in the specification, it is usually wise to use information from the
specification where possible.
7 a
Phloem transports (dissolved) sugars/is where translocation takes place (1) from the leaves to
the rest of the plant (for immediate use or storage) (1).
b
Phloem cells are elongated tubes. (1) They have pores in their end walls (to allow substances
to pass through). (1) [4 marks]
8 a
i
Transport of water (1)
ii
Cells have no end walls. (1) Side walls are thickened with lignin. (1)
In part a ii you were asked to state two ways in which xylem is adapted. This means that you only have to
answer how they are adapted and not how the adaptation helps the cell carry out its function.
b
i
Palisade mesophyll (1)
ii
Layer X is closer to the top of the leaf. (1) There are more chloroplasts in each cell. (1)
There are no air spaces (therefore more room for photosynthesising tissue). (1)
iii Guard cells (1)
iv To open and close the stomata/control the amount of water that evaporates out of the
plant. (1) [9 marks]
6
9 High temperatures (1); low humidity (1)
[2 marks]
Exam-style questions
10 a
b
Active site (1); lock and key (1)
Convert food into small, soluble molecules (1) that can be absorbed into the bloodstream (1).
c
i
Liver (1)
ii
Bile is alkaline so it neutralises HCl from the stomach. (1) It emulsifies fat/converts fat to
smaller droplets (1), thus increasing the surface area (1). The alkaline conditions/larger
surface area help speed up lipase activity. (1)
[9 marks]
11 a
To ensure that at time 0 the starch/amylase mixture was at the correct temperature. (1)
Otherwise the investigation would have taken place over a range of temperatures/results would
have been invalid/not repeatable/not reproducible. (1)
b
Any two from:

using the same volume of starch

using the same concentration of starch/amylase

using the same volume of pH buffer (2)
c
The time for the iodine to remain yellow-brown would be shorter at pH 7 than for the other two
pH values/the reaction is quicker at pH 7. (1) pH 7 is very close to the optimum pH for amylase
action. (1) At other pH values the active site is damaged/denatured (1) and therefore no longer
able to form a good fit with the starch (1).
d
Take samples more regularly than 30 seconds (e.g. every 15 seconds). (1)
[9 marks]
This type of question should remind students that they need to be very secure in their understanding of
terms such as precision, repeatable and reproducible.
12 Arteries have thick muscular walls/walls with large amounts of elastic tissue (1) because they carry
blood at high pressure/walls can expand and contract as blood pulses through (1). Veins have
thinner walls/valves (1) because the blood has a lower pressure/to prevent the backflow of blood
(1). Capillaries have walls one cell thick/that are very thin (1) to allow substances to pass between
the blood and the tissues (1). [6 marks]
13 a
b
i
Graphs are the same shape/distinctive curves are in the same place. (1)
ii
Lag between number of people smoking and number of people diagnosed with lung
cancer. (1)
Tar (1)
c
i
Cancer cells are smaller/have a larger nucleus. (1)
ii
The tumour is not confined to one position. (1)
7
iii Treat before spreading/treat while one tumour only (1) as more difficult to treat once
spread (1).
d
Depression (1) [8 marks]
14 a
i
Initially the higher the wind speed the faster the rate of transpiration (1) up until a
transpiration rate of 8/a wind speed of 9.5 (1) after that a higher wind speed leads to no
further increase in transpiration (1).
It is important to describe the variables in your answer — i.e. an answer such as ‘they both increase’ will
not get awarded.
ii
The higher the wind speed the greater the evaporation (1) up until a maximum rate is
achieved. (1)
iii During the night fewer stomata will be open (1) and therefore there will be fewer
pathways for water to evaporate (1).
b
i
The larger the leaf surface area the more stomata (1), and therefore more pathways for
water to evaporate (1).
ii
Advantage — reduced water loss (1)
Disadvantage — reduced photosynthesis (1)
[11 marks]
Infection and response
1
Disease
Type of
microorganism
involved
Virus (1)
Method of
spread
Method of prevention
Vaccination (1)
Salmonella (1)
Bacterium (1)
Barrier method of contraception (e.g.
condom)/avoidance of promiscuity (1)
[5 marks]
2 a
Mucus traps pathogens/microorganisms. (1) Cilia sweep them up to the throat (to be coughed
out or swallowed and destroyed in the stomach). (1)
b
i
The presence of antigens (in the body) (1)
ii
Lymphocytes (1)
iii The antibodies attach to the pathogens/microorganisms (1) because the antibodies are
an exact complementary fit to the antigens of the pathogens/microorganisms (1). The
pathogens/microorganisms are clumped together (so they cannot spread around the body
and cause harm). (1)
[7 marks]
8
Remember that the antibodies and antigens are not the same shape — they are complementary in shape
so that they can lock together. This is exactly the same principle as a substrate being complementary in
shape to the active site of an enzyme.
3 a
White blood cells engulf microorganisms (1). The white blood cells break down and digest
microorganisms. (1)
b
Antitoxins destroy/reduce the effect of toxins (poisons) produced by pathogens. (1)
marks]
[3
4 a
Antibiotics kill/destroy bacteria. (1) Painkillers treat disease symptoms/help reduce pain (but
have no effect on the pathogen). (1)
b
Alexander Fleming (1) [3 marks]
5 a
i
Fungus (1)
ii
By water (e.g. rain splash) and wind (1)
iii Removing and destroying infected leaves (1); using fungicides (1)
[4 marks]
6 a
Drug
Plant extracted from
Foxglove (1)
Aspirin
(1)
b
Function of drug
Treating heart disease (1)
Painkiller (1)
Toxicity — the degree of harm (if any) caused to the person/organisms taking the drug. (1)
Efficacy — how good the drug is at doing what it is meant to do (i.e. treating the disease). (1)
Dose — how much of the drug needs to be taken to have the desired effect. (1) [7 marks]
7 a
b
i
Magnesium deficiency (1)
ii
Plants cannot make chlorophyll (1), so light cannot be absorbed as effectively/there is
reduced photosynthesis (1).
Any two from:

gardening manuals/websites

bring infected plants to a laboratory for identification

using testing kits containing monoclonal antibodies (2)
[5 marks]
8 a
Tough and impermeable (1), so prevent harmful microorganisms/pathogens gaining entry (to
the plant) (1).
b
Herbivores will find the toxin distasteful/harmful (1) and so will avoid this plant/type of plant
(1).
9
c
Thorns/hairs/leaves that droop/curl when touched/mimicry to trick animals. (1)
[5 marks]
Exam-style questions
9 a
A disease that can be passed from person to person. (1)
Remember that communicable diseases can be passed from plant to plant too, but in the context of
human, the disease (in reality the disease-causing microorganisms or pathogens) will be passed from
person to person.
b
i
To avoid giving the individual the disease he/she is trying to avoid. (1)
ii
The pathogens in vaccinations contain antigens (1) that cause the body to produce
complementary antibodies (that can clump together and destroy the pathogens) (1). The
body also produces memory lymphocytes (1), which can produce large numbers of
antibodies very quickly if infected by the same pathogen at a later date (1).
Having a vaccination produces the same response in the body as having a particular disease and
recovering — in both, future protection is provided by the production of memory lymphocytes that can
produce antibodies very quickly and in high numbers.
iii By being infected by a different strain of flu (i.e. not the flu strain(s) that the vaccine
contained). (1) The different strain would have different antigens and therefore the body
would require antibodies complementary to these antigens. (1)
c
i
Antibiotics are only effective against bacteria. (1)
ii
Can lead to antibiotic resistance (in bacteria). (1)
[10 marks]
A surprising number of students in examinations seem to think that antibiotic resistance is something
that happens in humans.
10 a
Sexual contact (1); other exchange of body fluids, e.g. transfer of infected blood when drug
users share needles (1).
b
c
i
Decreases (1). The HIV virus attacks and destroys cells of the immune system. (1)
ii
The immune system has been very badly damaged. (1) Therefore the body can become
infected by infectious/communicable diseases (that it previously would have destroyed).
(1)
Antiretroviral drugs (1) [7 marks]
11 a
i
Protist (1)
ii
Fever (1)
iii Prevents/reduces access to mosquito breeding grounds. (1) Therefore there will be fewer
mosquitoes to spread the disease. (1)
b
10
i
There were fewer fresh bites among individuals using the new net (or converse). (1)
ii
Any two from:

all the individuals in the investigation living in same area/similar proximity to mosquito
breeding grounds

nets without insecticide/same amount of insecticide on nets

other appropriate response (e.g. same balance of ages/sex) (2)
In this type of question there are many possible answers, and examiners will normally credit any
appropriate answer. For example, the type of house used by the individuals in the test is a reasonable
answer, as some houses will be more resistant to insect entry than others. However, students should be
aware that not all variables can be controlled in this type of investigation. For example, it is not possible
to ensure that there are exactly the same number of mosquitoes in the vicinity of each house being used
in the investigation.
iii A larger-scale test involving more people/other areas (1)
[8 marks]
12 a
i
So that there will only be one type of lymphocyte (and one type of antibody) produced. (1)
ii
Enables the hybridoma cells to be long lived, thus producing many antibodies. (1)
Enables the hybridoma cells to produce many other cells by cloning that produce
antibodies. (1)
The key thing in this question is that the properties of the tumour (cancer) cells are incorporated in the
hybridoma cells, leading to maximum antibody production.
b
i
The monoclonal antibodies ensure that the drug can target cancer cells (as the antibodies
are complementary to the cancer cell antigens). (1) They deliver toxic drugs that can
destroy/kill cancer cells (1) without harming other cells in the body (1).
ii
Any two from:

pregnancy testing or other diagnosis

detecting pathogens or measuring hormone levels in the blood

detecting specific molecules in cells or tissues (by delivering fluorescent dyes to the
cells/tissues of interest) (2)
c
i
(9/400) × 100 (1)
= 2.3% (1)
When asked to give an answer to a certain number of significant figures it is important that you do — an
answer of 2.25% would be awarded 1 mark only.
ii
At the end of the trial/overall there was no significant change in the number of patients
surviving. (1) More patients survived taking the drug at the start of the trial. (1)
11
Appropriate use of data from the table, e.g. initially more effective as 181 were still alive in
2012 compared with 120 surviving after taking the placebo. (1)
iii Control/comparisons between those taking the drug and the placebo (those not taking the
drug). (1)
d
In case there is a problem with the drug/causes severe side effects. (1) Therefore, only a
limited number of individuals are harmed/affected. (1) [16 marks]
Bioenergetics
1 a
i
carbon dioxide + water (1) → glucose + oxygen (1)
ii
6CO2 + 6H2O (1)
light
→
C6H12O6 (1) + 6O2
chlorophyll
b
Photosynthesis is a process that only takes place in the presence of light (1) energy (1). [6
marks]
2 a
Chloroplasts (1)
Chlorophyll is not correct here because it is not a structure (unlike chloroplasts, which are structures).
b
i
5 (1)
ii
Temperature (1); carbon dioxide concentration (1)
[4 marks]
As the question specifically asks for ‘environmental’ variables, it is important to answer with temperature
and carbon dioxide concentration. There are many factors that affect the rate of photosynthesis, for
example number of chloroplasts, but this is not an environmental factor.
3 a
b
Move the lamp further away from the plant/use a dimmer switch in the lamp. (1)
Temperature (1); type of pondweed (1)
Although carbon dioxide concentration is a variable that could affect rate, it is not realistic for the levels
to be controlled accurately in this investigation by the investigator (in a GCSE setting).
c
4 a
i
Bubbles can be different sizes/bubbles may combine. (1) When counting, some bubbles
may be missed. (1)
ii
Collect the oxygen given off (using a gas syringe). (1)
glucose + oxygen (1) → energy + carbon dioxide + water (1)
b
Feature
Type of respiration
Aerobic Anaerobic
Oxygen used
12
[6 marks]
Carbon dioxide produced
Yes/no
Yes/no (1)
Lactic acid produced
Yes/no
Yes/no (1)
Amount of energy produced
High/low
High/low (1)
c
Anaerobic respiration in yeast produces alcohol/produces carbon dioxide/does not produce
lactic acid (or converse). (1) [6 marks]
5 a
b
Sum of all the reactions in a cell or the body (1)
Respiration (1), releasing energy from glucose/food (1).
c
The breakdown of food to form urea (1); the conversion of glucose to glycogen (1)
marks]
[5
Exam-style questions
6 a
Any two from:

converted to starch (for storage)

converted to fat or oil (for storage)

producing cellulose (to strengthen plant cell walls)

producing amino acids (for protein synthesis) (2)
b
i
No/very low levels of photosynthesis taking place (due to very low light levels). (1)
Respiration taking place, using (rather than releasing) oxygen. (1)
ii
Rates of photosynthesis and respiration are equal. (1). There is no net exchange of
oxygen. (1)
iii Carbon dioxide (1), because an increase in carbon dioxide causes an increase in the rate
of photosynthesis (1). It is not light because further increases in light at this point have no
effect. (1)
At position B, temperature could also be a limiting factor, but you have no evidence to suggest that it is.
The question asks you to use evidence from the graph and you do have evidence that carbon dioxide
levels are limiting the rate of photosynthesis at this point.
iv Higher plateau/line levelling off at a higher point. (1) Graph line initially same as other two
graph lines. (1)
c
i
Heaters to increase the temperature/fertiliser to add nutrients/artificial light to increase
light intensity/allow photosynthesis to continue for longer. (1)
ii
(Extra) carbon dioxide (1)
iii The cost of adding the environmental factors (to speed up the rates of photosynthesis).
(1) [14 marks]
7 a
C6H12O6 + 6O2 (1) → 6CO2 + 6H2O (1)
13
b
i
100 arbitrary units (1)
ii
The rate of breathing increased. (1)
iii During exercise more oxygen is needed (1) for more respiration (1) to release more
energy (for increased muscle contraction) (1).
c
i
To produce energy above and beyond the maximum that can be produced from aerobic
respiration. (1)
ii
The amount of extra oxygen required (1) to break down the lactic acid produced in
anaerobic respiration (1). [10 marks]
Paper 2
Homeostasis and response
1 a
The regulation (control) of the internal conditions of a cell or organism at optimum levels in
response to internal and/or external changes. (1)
b
Blood glucose level (1) [2 marks]
2 a
i
The central nervous system (1)
X could be either the brain or the spinal cord, but you have no evidence which it is. Therefore, it is better
to use the term central nervous system (CNS) in this answer. If the question had been ‘Name one
structure that X could be’, it would have been appropriate to answer with either the brain or the spinal
cord.
ii
(Sensory) neurones (1)
iii Direction in which nerve impulses travel. (1)
b
3 a
Electrical signals (1)
[4 marks]
Cerebral cortex — involved with thought, senses and voluntary actions. (1)
Cerebellum — coordination of movement and balance. (1)
There are many ways in which the functions of these parts of the brain could be described. Therefore,
there are many ways to answer correctly.
b
Electrically stimulating the different parts of the brain (1); MRI scanning (1)
c
The brain is a very complex organ. (1) It is also a very fragile (delicate) structure. (1)
marks]
4 a
Cornea (1); lens (1)
14
[6
b
5 a
b
i
Changing the shape of the lens to focus on near or distant objects. (1)
ii
C–A–D–B (all correct = 2; any two letters in correct sequence = 1) (2)
[5 marks]
Skin (1); brain (1)
Brain (1)
c
i
Blood vessels close to the skin close/constrict (1), reducing blood flow to the skin
(surface) (1). (As blood carries heat) less heat is lost to the atmosphere. (1)
ii
Reduced sweating (1); shivering (1) [8 marks]
You should be aware that thermoregulatory processes such as vasoconstriction and reduced sweating
reduce heat loss (they do not produce heat). Shivering does produce extra heat, so this can help raise
body temperature if it drops too low.
6 Endocrine (1); blood (1); pituitary (1) [3 marks]
7 a
b
Deaminated to form ammonia. (1) The ammonia is converted to urea. (1)
Liver (1)
[3 marks]
8
Hormone
Effect
Maturation of eggs (1)
Target organ
Ovary (1)
Stimulates the release of an egg (1)
Maintains the uterus lining (1)
[4 marks]
9 a
Oral contraceptive — inhibits FSH production (1)
Intrauterine device — prevents implantation (1)
b
c
i
Condom/diaphragm (1)
ii
Prevent the sperm reaching the egg (1)
Advantage — very reliable (1)
Disadvantage — very difficult or impossible to reverse (1)
10 a
[6 marks]
Adrenal glands (on top of the kidney) (1)
b
Adrenaline increases the heart rate. (1) More oxygen and glucose is supplied to the brain and
muscles (1) for more respiration/to produce more energy (1). [4 marks]
Adrenaline results in extra energy being produced, i.e. above and beyond what is normally produced. It is
this extra energy that can make the difference in a ‘flight-or-fight’ situation.
11 a
15
i
Ethene (1)
ii
Gibberellin (1)
i
The bending/growth of a plant shoot towards a light source/area where light intensity is
highest. (1)
ii
More auxin on shaded side (compared with illuminated side). (1) Auxin causes more cell
elongation. (1) Cells elongate more on shaded side (compared with illuminated side). (1)
This causes differential growth and the shoot bends in the direction of the light. (1)
[7
marks]
b
Exam-style questions
12 a
i
Relay (neurone) (1)
ii
Synapse (1)
iii Spinal cord (1)
iv A (1)
v
b
B (1)
Carry nerve impulses from the CNS/relay neurones to a muscle/effector (1)
c
i
Shorter pathways (1); conscious part of the brain not involved (1)
ii
Protection (1)
i
Meal rich in carbohydrate/glucose (1)
[9 marks]
13 a
It is important to state that it was a carbohydrate or glucose-rich meal that caused the increase in blood
sugar levels. A meal consisting of mainly protein or fat will not produce this effect.
ii
The rising blood glucose level caused an increase in insulin (1), produced by the
pancreas (1). The insulin caused more glucose to be taken into the cells (of the liver and
the muscles) (1), to be converted to glycogen (1).
iii The pancreas produces glucagon (1), which converts glycogen to glucose to be released
into the blood (1).
b
i
((141 − 94)/94) × 100 (1)
= 50% (1)
ii
The number of people with Type 1 diabetes is also increasing over time/there are more
people being treated for Type 2 than Type 1. (1)
16
iii Lack of exercise/too much carbohydrate (and fat) in the diet/obesity. (1)
c
i
Many people have diabetes (1); expensive instruments to measure blood glucose levels
(1); treatment of complications (1)
When you are asked to use only the information provided, you must get your answers from the
information provided only. An important skill is being able to work out which parts of the information
provided are necessary or helpful.
ii
14 a
(With good blood glucose control) less likely to develop complications. (1) Therefore less
likely to be affected by eye damage/blindness/kidney problems/less expense for the NHS
in treating complications. (1)
[16 marks]
From the lungs during exhalation (1); from the skin in sweat (1)
b
ADH production initially steady and high, and then falls (1) and levels off (1). Correct use of
data from the table, e.g. initially relatively steady around 10/falls after first 3 hours. (1)
When describing data in a table or graph it is important to make clear what is changing (in this case ADH
production) and how (here over time) – answers such as ‘it increases and falls’ seldom gain credit.
ci An increase in/high level of ADH causes the kidney tubules to be more permeable (1),
resulting in more water being absorbed from the tubules (1) back into the blood (1). Therefore, less
urine is produced. (1)
d
i
Urea is in a higher concentration in the blood (compared with the dialysis fluid). (1) Urea
diffuses from the blood into the dialysis fluid. (1)
ii
Protein is too large to pass through the dialysis tubing. (1) Glucose concentrations are the
same in the blood and the dialysis fluid (1) so there will be no loss by diffusion (1).
iii Kidney transplant (1)
15 a
[15 marks]
The lining becomes less thick until day 5. (1) It then increases. (1)
b
Days 10–13/just before ovulation (1), because oestrogen stimulates luteinising hormone (LH),
which is the hormone that actually causes ovulation (1).
c
d
i
Progesterone (1)
ii
To enable the embryo/ball of cells to attach/implant (1) and allow the transfer of nutrients
(and removal of waste) from the mother to the embryo (1).
Menstruation/breakdown of the uterus lining occurs again after 28 days. (1)
e
i
A ‘fertility’ drug containing FSH and LH may be taken (1) to stimulate egg production and
ovulation (1). IVF also involves the prescription of FSH and LH (1) to stimulate the
production of several eggs (1). The eggs are then collected from the mother and fertilised
by the father’s sperm (in a laboratory). (1) One or two embryos are then placed back into
mother’s uterus. (1)
17
ii
16 a
Can be emotionally and physically stressful/has a low success rate/can lead to multiple
births. (1) [15 marks]
Method:

Place (a number of) cuttings in compost after adding rooting powder and (a number of)
cuttings in compost without adding rooting powder. (1)

Leave for a period of time. (1)

Measure either number of new roots or length of roots in each cutting. (1)

(Use a number of cuttings in each treatment) so that mean values can be calculated to
increase repeatability. (1)
Controlled variables — any two from:
b

Leave each pot for the same length of time.

Keep in the same conditions or a named condition e.g. light levels, temperature, amount of
watering/

Use the same type/amount of compost in each pot. (2)
Weed killer (1); to promote growth in tissue culture (1)
[8 marks]
Inheritance, variation and evolution
1 a
i
It produces variation. (1)
ii
Male — pollen (1); female — egg cell (1)
i
Any two from:
b
ii

only one parent needed

no need to find a mate, thus saving time and energy

faster

many offspring can be produced when conditions are favourable (2)
Variation/allows natural selection to occur/enables selective breeding to take place (of the
best variants). (1) [6 marks]
2 a
Type of cell division
Mitosis
Meiosis
Reproductive organs (1)
Where it takes place
Involved in gamete
formation (yes or no)
No (1)
Yes (1)
18
Comparison with
parental cell
Same number of chromosomes
and the chromosomes are the
same (1)
Comparison with
other daughter cells
Same number of chromosomes but
the chromosomes are not the same
(1)
b
(All correct = 2; two or three correct = 1)
3 a
Sugar (1); phosphate group; (1) base (1)
b
A – T and C – G (1)
c
Any two from:
d
4 a
b
[7 marks]

hormones

structural proteins, e.g. collagen

other appropriate response, e.g. antibodies (2)
Switch genes on or off (1)
[7 marks]
Two X chromosomes (1)
46 (1)
[2 marks]
5 a
i
Dominant alleles are always expressed (even if only one present)/overrides the presence
of a recessive allele. (1) Recessive alleles are only expressed if both copies are present.
(1)
ii
If homozygous, both alleles will be the same. (1) If heterozygous, the two alleles are
different/one dominant allele and one recessive allele present. (1)
Many students find it much easier to identify dominant and recessive alleles or homozygous and
heterozygous genotypes in genetic diagrams than to explain what they mean. Nonetheless, you should
be able to explain each of the genetic terms, so it is worthwhile spending time learning a definition of
each.
b
3:1 — heterozygous × heterozygous (1)
1:1 — heterozygous × homozygous recessive (1)
19
[6 marks]
6 a
Recessive (1)
b
i
(Top) gametes correct (1); (left) gametes correct (1); offspring correct (1); ff genotype
identified as the child with cystic fibrosis (1)
ii
Three (1)
iii 0.25/25%/¼/1 in 4 (1)
[7 marks]
You will often be asked to work out probabilities in genetics questions. Remember that probability can be
represented in a number of different ways, as shown. In genetics questions you will also be asked to give
ratios, for example, you could be asked: ‘What is the ratio of offspring phenotypes in the above Punnett
square?’ The answer would be: ‘without cystic fibrosis, 3 : with cystic fibrosis, 1’.
7 a
Differences in a characteristic among the individuals in a population (1)
b
i
62 – 3 (1)
= 59 (1)
It is important to read all questions carefully and a seemingly straightforward one like this is no
exception — did anyone calculate the difference in numbers between blood groups A and O (the most
obvious bars)?
ii
(65/112) × 100 (1)
= 58% (1)
iii Small number of groups/no intermediate values (1)
iv Environmental (1)
[7 marks]
8 2 – 3 –1 (1) [1 mark]
9 a
b
Humans breeding plants and animals for particular characteristics. (1)
Any two from:

more milk/meat

dogs with a gentle nature

other appropriate example, e.g. dogs of a particular size, type or colour of fur (2)
marks]
20
[3
There are many possible answers to this question that could be credited. However, in this type of
question it is important to read the question very carefully. For example, answers such as showy flowers
or disease-resistant crops would not get rewarded because the question is only asking about animals.
10 a
A crop in which the plants have a gene (DNA) added from another organism. (1)
b
Resistant to insect attack/resistant to herbicides/increased yield/other appropriate response
(1)
c
Concerns about affecting populations of wildflowers and insects/concerns that the potential
effects on humans have not been fully explored as yet/other appropriate response. (1) [3 marks]
11 a
Splitting apart cells within an embryo before the cells have differentiated/dividing an embryo
into two or more sections before cell differentiation takes place. (1) Then transferring the split
embryo sections into host (surrogate) mothers. (1)
It is very important that the embryo is split before the cells have differentiated, otherwise the individual
embryo sections would not be able to form all the cells required.
b
All the offspring will be identical and have the (desired) characteristics of the original embryo/if
all the embryos are implanted at the same time all the offspring will be born at the same time
(allowing easier management of staff/vets etc). (1)
[3 marks]
12 a
i
(Charles) Darwin (1)
ii
Any two from:

It challenged the idea that God created all the living organisms present on Earth.

There was insufficient evidence to show how organisms have evolved over time.

The mechanisms of variation and inheritance were not understood until well after the
theory of evolution was first proposed. (2)
b
Scientist
Wallace (1)
Contribution
The changes in an organism during its
lifetime can be passed on to offspring (1)
[5 marks]
13 a
b
The preserved remains of organisms from millions of years ago (usually found in rocks). (1)
Any two from:

The organism or sections of it do not decay.

Parts of the organism are replaced by minerals as they decay.

They remain as preserved traces, e.g. footprints or burrows. (2)
21
c
The early organisms were soft bodied (there were no hard parts, which fossilise much more
easily)/the very old rocks from the time when life began have been significantly changed due to
geological activity. (1)
[4 marks]
14 (Kingdom) – phylum – class – order – family – genus – species (all correct = 2; one group in wrong
place = 1) [2 marks]
Exam-style questions
15 a
The entire genetic material of that organism (1)
b
c
i
Genes (1)
ii
Nucleus (1)
Double helix (1)
d
i
CAGCTTGGG (1)
ii
Three (1)
iii The base sequence for each amino acid is different. (1)
iv Protein (1)
e
The (second) amino acid would be different. (1) Therefore the final protein formed would be
different/have a different amino acid in one position. (1) The protein may not be able to fulfil its
normal function. (1) [11 marks]
16 a
i
One parent’s gametes Aa (1); the other parent’s gametes aa (1); offspring correct, as
shown in Punnett square (1)
ii
0.5/50%/½/1 in 2 (1)
i
Aa and Aa (1)
ii
AA or Aa (1)
b
[6 marks]
22
17 a
i
Some plants had more toxins than other plants/phenotypes varied in terms of toxin
concentrations. (1) The plants with more toxin were more able to avoid being eaten by
slugs. (1) The plants with no (or small levels of) toxin had no defence against being eaten
by slugs. (1) The plants with toxin were more likely to survive and pass their genes on to
the next generation. (1) Over time the number of plants with high levels of toxin
increased/the number of plants with low levels of toxin decreased. (1)
ii
The number of garlic plants would decrease (1) because they would have no defence
against the slugs/very low toxin levels would not protect against the slugs (1).
i
Y — much less variable (1)
ii
Only those plants with high yields were used to breed (1) over many generations (1).
Eventually all the plants had a high yield. (1)
b
iii Selective breeding involves humans/humans are not involved in natural
selection/(normally) selective breeding is a faster process than natural selection. (1) [12
marks]
18 a
A process that involves modifying the genome of an organism by introducing a gene/DNA
from another organism to give a desired characteristic. (1)
b
i
Reduces blood glucose levels (1)
ii
Any two from:

Cattle and pig insulin is slightly different in structure from human insulin (so may not
be as effective in humans).

It avoids the possibility of transferring viruses/microbes from domestic animals.

It can be mass produced. (2)
c
d
i
It allows the introduced gene to bind effectively into the plasmid (1) using matching base
pairs (1).
ii
The plasmid (containing the human insulin gene) is taken up by a bacterium. (1) The
bacteria are cultured in optimum conditions (1) to maximise production of the insulin (1).
Virus (1)
[10 marks]
19 a
i
Mutation (1)
ii
A bacterium/microbe that is resistant to a number of antibiotics. (1)
23
iii Reduce the number of antibiotic prescriptions (i.e. do not prescribe for viral or non-serious
infections). (1) When prescribed, patients should complete the full course of antibiotics.
(1) Restrict the use of antibiotics in agriculture. (1)
b
i
The numbers of A decreased dramatically/sharply. (1) The numbers of B rose steadily. (1)
It would not be enough to state that numbers of A fell and numbers of B rose to get 2 marks. Although it
seems obvious what is happening, a fuller description describing the rate of change gives much more
information. Also, in a describe question, you only have to answer ‘what’ is happening — the
‘why’/explanation is covered in part (ii).
ii
Bacteria A were killed by the antibiotic. (1) Numbers of B rose steadily due to reduced
competition from bacteria A. (1)
c
Natural selection, because the best adapted (the resistant bacteria) survived when the
antibiotic was added, whereas the non-resistant bacteria were killed. (1) Evolution, because, over
time, the bacteria were (nearly) all resistant and had a different genotype than at the start of the
investigation. (1)
[11 marks]
20 a
i
(Carl) Linnaeus (1)
ii
Two (1)
iii Four (1)
b
i
Better microscopes/greater understanding of biochemical processes. (1)
ii
Archaea (1) bacteria (1) eukaryotes (1)
[7 marks]
Ecology
1 a
The interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of
the environment. (1)
b
2 a
Water (1); light (1); space (1)
[4 marks]
Behavioural/functional (1)
b
High temperatures (e.g. in deserts)/high pressures (e.g. at the bottom of deep seas)/high salt
levels (e.g. in dried-up sea beds) (1) [2 marks]
3 a
Grass (1)
b
Foxes (1)
c
One (1) [3 marks]
4 a
0.5 m (1)
b
24
i
Use random numbers to identify, e.g., 20 quadrat positions. (1) Count the number of
plantain plants in the quadrat when in each position. (1) Calculate the mean number per
quadrat (over the 20 quadrats). (1) Calculate the mean number per square metre and
multiply by the area of the pitch in square metres (or equivalent calculation). (1)
ii
20 plants per m2 (1)
football pitch = 5000 m2 (1)
5000 × 20 = 100 000 plants (1)
5 a
b
6 a
[8 marks]
The variety of all the different species of living organism on Earth, or within an ecosystem. (1)
Any two from:

sewage

fertiliser

toxic chemicals (2)
[3 marks]
Garden compost/as a fuel (1)
b
To conserve (the rare) peatland habitat/to conserve (the rare) species present. (1) To reduce
carbon emissions (if the peat is used as a fuel). (1) [3 marks]
7 a
i
Takes up land/releases toxic chemicals /other appropriate response (1)
ii
Recycling/incineration/other appropriate response (e.g. increasing the proportion of
material that is biodegradable) (1)
b
It increases the variety of plants growing in an area. (1) It provides food and shelter for insects
and other small animals. (1) [4 marks]
8 a
Trophic level 1 (1)
b
Trophic level 2 (1)
c
Two (1)
d
Four levels shown, each bar of equal depth and symmetrical on each side of central axis. (1)
Pyramid shape, with decreasing width of bars from bottom to top. (1) Each bar correctly labelled.
(1) [6 marks]
9 a
More food required because increasing number of people to feed/increased amount of land
needed for housing (therefore less available for agriculture)/other appropriate response. (1)
b
Any two from:

changing diets

new pests/pathogens

environmental change (e.g. reduced rainfall/higher temperatures linked to global warming)

cost of agricultural inputs
25

conflict/wars (2)
[3 marks]
10 a
Animals are able to move less (1), meaning a reduction in energy lost in movement (1).
Higher temperatures (1) result in less heat loss (and saving energy in maintaining a constant
temperature) (1).
b
Damage to joints (through being on concrete floors most of the time)/stress/ethical
reasons/other appropriate response (1)
[5 marks]
11 a
A limit on net sizes (1); a limit on how many fish can be caught (quotas) (1)
b
Smaller fish are not caught (as they are able to slip through the larger mesh size) (1), and
therefore survive to breed (1).
[4 marks]
Exam-style questions
12 a
i
A living environmental factor in an ecosystem. (1)
ii
New primary consumers/herbivores (that feed on the plants)/new pathogens/competition
from other living organisms. (1)
Although the specification makes reference to predators or prey in the context of a biotic factor, in the
case of plants it would be a new primary consumer or herbivore.
b
i
Any five from:

rhododendron lets very little light through

preventing other plants from photosynthesising

spreads rapidly/is large

little space available for other plants

other plant species die out/cannot grow

fewer habitats/less food for animals (5)
In this type of question students are not expected to have learned the exact answer from their notes.
However, they will be expected to use their biological understanding to deduce the effect of the
rhododendron on other plants. It is also very important to read the information provided carefully, as this
determines the type of answer required.
ii
c
Cutting the rhododendron/other appropriate response (1)
Any two from:

food

mates

territory (2) [10 marks]
26
13 a
The area being investigated is not uniform/environmental gradient up the shore. (1) Therefore
the species being sampled will not be distributed uniformly. (1)
b
i
17/40 = 0.425 (1)
= 43% (to 2 significant figures) (1)
Remember that if you do not show your working you will not get any marks for getting part of the
calculation correct — you will only be rewarded if you get the correct answer. When asked to give an
answer to 2 significant figures, you will usually be penalised a mark if you do not do this, e.g. an answer
of 42.5% = 1 mark only.
ii
Seaweed present from 1 m to 21 m/low tide mark to 21 metres/1st to 21st quadrat
position (1); but none from 15–18 m/15th to 18th quadrat (1); none beyond 21 m up the
shore (1)
iii Able to withstand strong tides/wave action/able to withstand drying out for short periods of
time/any appropriate answer. (1)
c
The seaweed being sampled occurs only in the lower section of the shore. (1)
[9 marks]
14 a
i
8/7 (1)
= 1.14 (1)
ii
The temperature in the compost bin increased to a peak (1) and then fell again (1).
Correct reference to data from the table, e.g. reached a peak of 48. (1)
iii Over time the decomposing microorganisms produced heat (1) due to respiration (1).
iv To allow oxygen to enter (1) for aerobic respiration (1) by decomposing microorganisms
(1).
‘Oxygen’ is necessary in the first marking point — ‘air’ is not specific enough
b
15 a
Decomposition takes place faster in warmer temperatures. (1)
[11 marks]
Photosynthesis (1)
b
R labels on all three respiration arrows (from organic compounds in plants plus animals and
microbes to the carbon dioxide box). (1)
c
i
Deforestation reducing photosynthesis (and therefore the carbon dioxide taken out of the
atmosphere). (1) Increased burning of fossil fuels (and therefore increasing carbon
dioxide levels entering the atmosphere). (1)
ii
Methane/other appropriate example (1)
i
A carnivore with no predators (1)
16 a
27
[5 marks]
ii
They secrete enzymes into the soil/onto the dead organism. (1) The enzymes digest the
dead (organic) material. (1) The soluble products then diffuse into the decomposer. (1)
i
9 × 104 × 100 (1)
b
= 9 × 106 (1)
Or
90 000 × 100 (1)
= 9 000 000 (1)
ii
Any two from:

losses in faeces

losses due to respiration (e.g. as carbon dioxide, water and heat)

losses in urine (e.g. water and urea) (2)
iii (2 × 103/15 × 103) × 100 (1)
= 13.3% (1)
Or
(2000/15 000) × 100 (1)
13.3% (1)
[10 marks]
28