GCSE Evaluate and Conclusion Questions

8 Questions (all contain an evaluation or form a conclusion element).

107 marks
Time 113 minutes

Q1.
A food web contains several food chains.

Figure 1 shows a food web.

Figure 1

(a) The animals in Figure 1 get their energy by eating other organisms.

Describe how the algae get energy.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(2)

(b) Name one primary consumer in Figure 1.

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Page 1 of 37
 (1)

(c) Name one producer in Figure 1.

___________________________________________________________________
(1)

(d) The different food chains in Figure 1 have different numbers of organisms.

Complete Figure 2 to show a food chain in Figure 1 with five organisms, including
the human.

Figure 2

(1)

(e) Figure 1 shows that mackerel eat krill and squid.

The biomass of mackerel is much less than the combined biomass of krill and squid.

One reason for this is that the mackerel cannot digest all parts of the krill and squid.

Give two other reasons.

1 ________________________________________________________________

___________________________________________________________________

2 ________________________________________________________________

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(2)

Figure 3 shows how the biomass of adult herring in the North Sea has changed between
1950 and 2010.

Figure 3

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(f) Calculate the percentage decrease in the biomass of herring between 1960 and
1977.

Give your answer to the nearest whole number.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Percentage decrease = _______________ %

(4)

(g) Too many herring were caught by fishermen between 1960 and 1977.

Herring can live for up to 12 years and begin to reproduce when 3 to 4 years old.

Laws have been introduced to help conserve herring:

• 1977 to 1981 – herring fishing was banned in the North Sea
• 1984 to present day – control of mesh size of fishing nets
• 1997 to present day – fishing quotas were introduced
• 1998 to present day – herring fishing was banned in breeding grounds during
the breeding season.

Figure 4 shows how a minimum mesh size helps to conserve herring.

Figure 4

Page 3 of 37
Figure 3 is repeated below.

Figure 3

Evaluate the effect of these laws on the conservation of herring stocks.

Use data from Figure 3 and information from Figure 4 in your answer.

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 ___________________________________________________________________

___________________________________________________________________
(6)
(Total 17 marks)

Q2.
It is important to keep the blood glucose concentration within narrow limits.

(a) A person eats a meal containing a lot of carbohydrate. This causes an increase in
the person’s blood glucose concentration.

Explain how the hormones insulin and glucagon control the person’s blood glucose
concentration after the meal.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

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___________________________________________________________________

___________________________________________________________________

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(5)

(b) The body cells of a person with Type 2 diabetes do not respond to insulin.

A person with Type 2 diabetes often has a higher blood insulin concentration than a
non-diabetic person.

Explain why.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Page 5 of 37
 (3)

Metformin is a drug used for treating people who have Type 2 diabetes.

Scientists investigated the effects of metformin and two other drugs, A and B.

The scientists wanted to see how the drugs affected the blood glucose concentrations of
220 people with Type 2 diabetes.

This is the method used.

1. Put the 220 people into five groups.

2. Treat each group with a different drug or combination of drugs for several weeks.

3. Give each person a meal high in carbohydrate.

4. Measure the blood glucose concentration of each person 30 minutes after the meal and
again 3 hours after the meal.

(c) Suggest three variables that the scientists should have controlled in the
investigation.

1 _________________________________________________________________

___________________________________________________________________

2 _________________________________________________________________

___________________________________________________________________

3 _________________________________________________________________

___________________________________________________________________
(3)

The scientists recorded their results as a mean value for each group.

The scientists calculated the ‘standard deviation’ for each group’s result.

Standard deviation is a measure of the spread of the individual results above or below (±)
the mean value.

The scientists gave each group’s result as:

mean ± standard deviation

The larger the standard deviation, the greater is the spread of results around the mean.

(d) Which of the results is the most precise?

Tick (✓) one box.

Mean = 171.6 ± 16.3

Page 6 of 37
 Mean = 177.2 ± 15.4

Mean = 182.5 ± 18.2

Mean = 205.2 ± 19.4

(1)

The following table and the figure show the scientists’ results.

Metformin Metformin
Drugs used Metformin A B
+A +B

Number of people 60 40 25 65 30

Mean blood
glucose
concentration 30
177.2 182.5 171.6 205.2 206.5
minutes after the
± 15.4 ± 18.2 ± 16.3 ± 19.4 ± 19.6
meal in mg/100 cm3
± standard
deviation

Page 7 of 37
In the table and the figure some standard deviations of results overlap.

• An overlap of standard deviations shows the difference between the means is not
significant.

• No overlap of standard deviations shows a significant difference between the

means.

(e) A student looked at the scientists’ method and the results in the table and figure
above.

The student stated:

‘Metformin works better when used with other drugs.’

Evaluate the student’s statement.

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Page 8 of 37
 ___________________________________________________________________

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(6)
(Total 18 marks)

Q3.
Professor John Lawton researches into the problem of controlling the spread of bracken.
Bracken is a fern which threatens upland farms, partly because it poses a health risk to
people and animals.

Professor Lawton is waiting for government permission to release the Conservular

caterpillar which feeds on the bracken.

The Secretary of State has to decide whether the Conservular caterpillar can be released.

The article printed below describes some of the problems faced by the Secretary of State.

David the caterpillar to bracken’s Goliath

Yorkshire farmer Maurice Cottrill has just forked out £500 to have a helicopter
hover over his land and spew out gallons of chemicals aimed at destroying
one of the most pervasive and dangerous weeds known to man – bracken. In
a little box in a laboratory near Ascot, Berkshire, lies a tiny caterpillar which
could have done the job for nothing.

Whether or not that caterpillar and thousand of its chums will ever be let loose
on the massive carpet of bracken that is sweeping over Britain at the rate of
53 square kilometres a year has to be decided by the Secretary of State for
the Environment.

Weed control through the release of imported insects has never been tried in
Britain before. If the Secretary of State permits the experiment, the caterpillar
is in for the feast of its life, because five years of painstaking research have
proved that bracken is its only food. However, is that the full story? Will the
beast stop there, or will it go on, wreaking unforeseen devastation. Can
scientists predict what will happen when imported insects are released into
the wild?

Bracken is poisonous – more than 20 000 sheep and 1 000 cattle suffer
poisoning each year. Its spores are carcinogenic, posing a threat to hill
walkers. Bracken costs a depressing £4m a year to control while rendering

Page 9 of 37
 useless grazing land valued at £5m annually. “Bracken is one factor which is
leading to hill farming becoming uneconomic”, says the director of the
Ramblers Association. “We are worried about that because, the more
uneconomic hill farms become, the more prospect there is of the forestry
industry taking over.”

The National Farmers Union are concerned about the consequences of the
caterpillar getting out of control. What if it started consuming garden ferns?
What if it loved potatoes? On the other hand, the caterpillar might help to
preserve important uplands where wildlife flourishes when bracken is kept at
bay. However, the experiment takes the scientists into unknown territory.

World-wide, 94 species of weeds have been controlled by biological releases

involving 215 types of animal in 50 countries. Professor Lawson says that
approximately one-third have achieved effective control and the remainder
have failed.

Upland farms are artificial ecosystems, created and maintained mainly for the rearing of
sheep and cattle. These farms are being threatened by the spread of bracken. Up to now
the only treatment for bracken has been to use herbicides.

Use the article to explain, as fully as you can, what advice you would give the Secretary of
State.

Explain the arguments for and against that lead to your decision.

You will not receive marks for simply copying extracts from the article.
(Total 8 marks)

Q4.
Some students wanted to estimate the number of plantain plants in a grassy field.

The field measured 100 metres × 50 metres.

The students:
• chose areas where plantains were growing
• placed 10 quadrats in these areas
• counted the number of plantains in each of the 10 quadrats.

Each quadrat measured 25 cm × 25 cm.

The table below shows the students’ results.

Quadrat Number of
number plantain plants

1 2

2 1

3 4

4 1

5 3

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 6 2

7 4

8 1

9 1

10 1

(a) Complete the following calculation to estimate the number of plantain plants in the
field.

Use the students’ results from the table above.

Total number of plantains in 10 quadrats = ____________________________

Total area of 10 quadrats = _____________________________________ m2

Mean number of plantains per m2 = ________________________________

___________________________________________________________________

Area of field = _______________________________________________ m2

Therefore estimated number of plantains in field = _____________________

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(3)

(b) The students’ method would not give a valid estimate of the number of plantain
plants in the field.

Describe three improvements you could make to the students’ method.

For each improvement, give the reason why your method would produce more valid
results than the students’ method.

Improvement 1 ______________________________________________________

Reason ____________________________________________________________

___________________________________________________________________

Improvement 2 ______________________________________________________

Reason ____________________________________________________________

___________________________________________________________________

Improvement 3 ______________________________________________________

Reason ____________________________________________________________

___________________________________________________________________
(3)
(Total 6 marks)

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Q5.
Gases enter and leave the blood by diffusion.

(a) Define the term diffusion.

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___________________________________________________________________
(1)

(b) Name the main gases that diffuse into and out of the blood in the lungs.

Into the blood _________________________________

Out of the blood _______________________________

(1)

(c) Smoking can cause emphysema.

Look at Figure 1 below.

Emphysema causes the walls of the air sacs in the lungs to break down

Explain how this will affect the diffusion of gases into and out of the blood.

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(2)

Smoking during pregnancy can cause low birth mass in babies.

Table 1 shows the World Health Organisation categories for birth mass.

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 Table 1

Category Birth mass in g

Above normal birth mass > 4500

Normal birth mass 2500–4500

Low birth mass 1500–2499

Very low birth mass 1000–1499

Extremely low birth mass < 1000

(d) Complete Table 2.

Use information in Table 1.

Table 2

Baby Birth mass in g Category

A 2678 Normal birth mass

B 1345

C 991
(2)

Figure 2 shows data from a study about pregnancy and smoking in women in the UK.

Page 13 of 37
(e) Sampling from the whole UK population would not be appropriate for this study.

Give one reason why.

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___________________________________________________________________
(1)

(f) Give three conclusions that can be made about smoking in pregnant women
compared with non-pregnant women.

Use information from Figure 2.

1. _________________________________________________________________

___________________________________________________________________

2. _________________________________________________________________

___________________________________________________________________

3. _________________________________________________________________

___________________________________________________________________
(3)

Page 14 of 37
Other factors can also be linked to low birth mass.

Figure 3 shows the relationship between four of these factors and the risk of low birth
mass.

(g) What type of graph is shown in Figure 3?

Tick one box.

Bar graph

Histogram

Line graph

Page 15 of 37
 Scatter graph

(1)

(h) Which of the graphs in Figure 3 shows a positive correlation?

Tick one box.

A B C D

(1)

(i) A student concluded that the longer a woman spends giving birth, the greater the
risk of low birth mass.

Give one reason why the student’s conclusion is not correct.

Use evidence from Figure 3.

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___________________________________________________________________
(1)
(Total 13 marks)

Q6.
The limpet is a snail-like animal that lives attached to a rock on the seashore.

Some students investigated variation in the size of limpets living on two seashores:
• one shore was in a sheltered bay
• the other shore was exposed to the full force of the sea.

The students measured the heights (H) and widths (W) of 60 limpets on each shore.

Figure 1 shows a limpet and the measurements made by the students.

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(a) On each shore, the students measured a large number of limpets at random
locations.

Explain why the students did this.

Large number of limpets:

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Random locations:
____________________________________________________

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(2)

The students calculated for each limpet.

The table below shows the students’ results.

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(b) Complete the table above.
(1)

Figure 2 shows some of the results.

Page 18 of 37
(c) Complete Figure 2.
(1)

(d) Compare the patterns in the results for the exposed shore and the sheltered shore.

Use information from Figure 2.

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(3)

Figure 3 shows how the students measured the width of a limpet with a vernier calliper.

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(e) One student recorded

• sheltered shore: mean = 0.4659182

• exposed shore: mean = 0.3542183

The student’s teacher stated that the data did not justify such a high number of
decimal places.

Give the two mean values corrected to an appropriate number of decimal places.

Sheltered shore: mean = ____________________

Exposed shore: mean = ____________________

(2)

(f) A limpet clings to a rock on the sea shore using its muscular ‘foot’, as shown in
Figure 1.

Scientists have found that limpets can exert a force of 2 newtons / cm2 of ‘foot’.

To remain attached to its rock, a limpet must exert a force at least as large as the
force of the waves.

Calculate the maximum wave force the limpet shown in Figure 3 could withstand
without being knocked off its rock.

Assume that the surface of the foot is a circle.

The area of a circle is πr2.

Page 20 of 37
 Take the value of π to be 3.14.

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Maximum wave force = ____________________ newtons

(3)

(g) Suggest two reasons why your answer to Question (e) might not be very accurate.

1. _________________________________________________________________

___________________________________________________________________

2. _________________________________________________________________

___________________________________________________________________
(2)

(h) Suggest biological reasons for the lower mean values for limpets on the exposed
shore.

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(3)
(Total 17 marks)

Q7.
Stem cells can be used to treat some diseases.

(a) What is a stem cell?

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 ___________________________________________________________________
(2)

Figure 1 shows a malignant tumour in the trachea of a patient.

(b) Give one way a malignant tumour differs from a benign tumour.

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___________________________________________________________________
(1)

Scientists can treat the patient’s tumour by replacing the trachea with a plastic trachea.

The plastic trachea has a layer of the patient’s own stem cells covering it.

Figure 2 shows the procedure.

Page 22 of 37
(c) In Step 3 the cells are left for 48 hours to divide.

Name the type of cell division in Step 3.

___________________________________________________________________
(1)

(d) In Step 3 the cells are given oxygen and water.

Name two other substances the cells need so they can grow and divide.

1. _________________________________________________________________

2. _________________________________________________________________
(2)

(e) Give two advantages of using the stem cell trachea compared with a trachea from a
dead human donor.

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 1. _________________________________________________________________

___________________________________________________________________

2. _________________________________________________________________

___________________________________________________________________
(2)

(f) Sometimes the stem cell trachea is not strong enough.

Doctors can put a stent into the trachea.

Suggest how a stent in the trachea helps to keep the patient alive.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(2)

(g) Stem cells can also be obtained from human embryos.

Evaluate the use of stem cells from a patient’s own bone marrow instead of stem
cells from an embryo.

Give a conclusion to your answer.

___________________________________________________________________

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(6)
(Total 16 marks)

Q8.
A virus called RSV causes severe respiratory disease.

(a) Suggest two precautions that a person with RSV could take to reduce the spread of
the virus to other people.

1. _________________________________________________________________

Page 24 of 37
 ___________________________________________________________________

2. _________________________________________________________________

___________________________________________________________________
(2)

(b) One treatment for RSV uses monoclonal antibodies which can be injected into the
patient.

Scientists can produce monoclonal antibodies using mice.

The first step is to inject the virus into a mouse.

Describe the remaining steps in the procedure to produce monoclonal antibodies.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(3)

(c) Describe how injecting a monoclonal antibody for RSV helps to treat a patient
suffering with the disease.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(2)

A trial was carried out to assess the effectiveness of using monoclonal antibodies to treat
patients with RSV.

Some patients were given a placebo.

(d) Why were some patients given a placebo?

___________________________________________________________________

___________________________________________________________________
(1)

A number of patients had to be admitted to hospital as they became so ill with RSV.

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The results are shown in the table below.

Treatment received by patient % of patients within each group

admitted to hospital with RSV

Group A: Monoclonal antibody for RSV 4.8

Group B: Placebo 10.4

The trial involved 1 500 patients.

• Half of the patients (group A) were given the monoclonal antibodies.
• Half of the patients (group B) were given the placebo.

(e) Calculate the total number of patients admitted to hospital with RSV during the trial.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Total number of patients admitted to hospital = ____________________

(2)

(f) Evaluate how well the data in the table above supports the conclusion:

‘monoclonal antibodies are more effective at treating RSV than a placebo’.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(2)
(Total 12 marks)

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Mark schemes

Q1.
(a) from light / sunlight
ignore sun unqualified
1

absorbed by chlorophyll / chloroplasts

if no other mark awarded allow by photosynthesis
for 1 mark
1

(b) krill / herring / copepod

1

(c) algae
1

(d) 1 algae
2 krill or copepod
3 squid
4 mackerel
(5 Human)
all correct for 1 mark
1

(e) any two from: (losses due to)

• non-eaten parts (of squid / krill)

allow bones / shells
allow eaten by other animals

• respiration or respiring (in mackerel)

do not accept respiration produces / makes /
creates energy

• excretion (by mackerel)

allow loss of a named waste product such as
CO2 / urea
ignore loss of waste unqualified
ignore faeces
2

(f) 2.3 and 0.1 (million)

allow in the range 2.25 to 2.3 for 2.3 (million)
1

95.65217.....
allow answer from correct substitution of
incorrect values from Figure 3
1

Page 27 of 37
 96
allow student’s calculated answer correctly
rounded to the nearest whole number
1

(g) Level 3: A judgement, strongly linked and logically supported by a sufficient

range of correct reasons, is given.
5−6

Level 2: Some logically linked reasons are given. There may also be a simple
judgement.
3−4

Level 1: Relevant points are made. They are not logically linked. 1–2
1−2

No relevant content
0

Indicative content
figures may be given without units (million tonnes) throughout

points for:
• small fish are not caught so can live long enough to reproduce
• biomass / stocks have generally increased after these laws introduced
• ’77-’81 law (total ban) resulted in increase in biomass, eg 0.1 to 0.48 or
to 0.9 by ’84
• ’84 law (mesh size) resulted in increase in biomass, eg 0.9 to 1.8 (by
’90)
• ’97 law (quotas) resulted in increase, eg 1.15 to 1.25
• ’98 law (ban in breeding season) resulted in increase, eg 1.25 to 2.5

points against:
• could be a cause other than the law or correlation does not necessarily
indicate causal relationship or other factors
• laws superimposed so can’t necessarily tell the effect of each
• each law results in an increase followed by a decrease
• quotas lead to dead fish being thrown back into sea

For Level 3 points both for and against must be considered together with
appropriate use of data
[17]

Q2.
(a)
ignore incorrect organ secreting insulin /
glucagon

(blood glucose increases after meal causing) insulin secretion

allow (blood glucose increases after meal
causing) insulin increase
1

insulin causes glucose to enter cells / liver / muscles

1

(insulin causes) glucose conversion to glycogen

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 1
allow glucose converted to glycogen in cells /
liver / muscles for 2 marks

(so) blood glucose decreases causing glucagon secretion

allow increase in glucagon when blood glucose is
low
1

glucagon causes glycogen to be converted to glucose

1

(b) cells / liver / muscles absorb less glucose

allow cells / liver / muscles convert less glucose
to glycogen
do not accept no absorption / conversion of
glucose
1

(so) glucose concentration in blood remains high

allow (so) glucose concentration in blood does
not decrease
1

(high blood glucose stimulates / causes) pancreas to release more insulin

allow more insulin is released from pancreas to
‘try’ to reduce blood glucose
1

(c) any three from:

• age
• height and mass
allow BMI
• proportion of males and females or group size
allow sex of the participants
• (same) severity of diabetes
• (same) activity (during investigation)
• (same) type of meal
• dose of drug
• (similar) blood glucose concentrations at start
allow how much / type of food / drink consumed
before
• other health conditions or other drugs being taken
allow may not have followed drug-taking regime
beforehand
3

(d) Mean = 177.2 + 15.4

1

(e) Level 3: A judgement, strongly linked and logically supported

by a sufficient range of correct reasons, is given.
5–6

Level 2: Some logically linked reasons are given. There may

also be a simple judgement.
3–4

Level 1: Relevant points are made. They are not logically

Page 29 of 37
 linked.
1–2

No relevant content
0

Indicative content

Pro:
• Met + A gives larger (%) reduction (in blood glucose) than Met alone
• so statement is supported

• Met + B gives larger (%) reduction (in blood glucose) than Met alone
• so statement is supported

• Met + A SD does not overlap with Met SD

• so difference is significant

Con:
• Met + B SD overlaps with Met SD
• so difference is not significant
• difference in results could be due to chance

----------------------------------------------------------------------------------------------
• number of people used is not very large
• number of people in each group is different
• so may not be representative or may not be repeatable / reproducible
• so anomalies will have a bigger impact on smaller groups

• 30 minute / starting levels of blood glucose are different

• all 30 minute / starting levels are higher in the 2-drug trial
• so may cause different % reductions

• no information about control variables or named e.g.

• concentration of drugs not given / may differ
• so results may not be valid

for level 3 an inclusion of a discussion of significance is required

[18]

Q3.
Cogently argued based on biological principles, for and
against introduction of caterpillar
maximum of 4 pros e.g.
fewer chemicals used therefore less expense
less chemical damage to other plants
consequent benefits to food chains
fewer farm animals poisoned therefore more economic
countryside more varied therefore more attractive to tourists
tourists bring economic advantages
greater variety of habitats therefore greater variety of species
any 4 for 1 mark each
4

cons e.g.
danger to livelihoods if crops destroyed by caterpillar
relatively low chance of success since only one third of schemes

Page 30 of 37
 effective world-wide
unlikely to be natural predators therefore ecological balance affected
any 2 for 1 mark each
2

cogently argued case gains up to 2 marks

2
[8]

Q4.
(a) 160 000
if incorrect answer / no answer:
allow max. 2 for method:
1 mark for mean = total number ÷ area of ten quadrats

eg or or or 32
1 mark for final answer = mean × field area
eg mean × 5000
3

(b) Improvement: place quadrats randomly

and
Reason: avoid bias / (more) representative / (more) reliable
allow 1 mark if 2 correct improvements but no reasons / only
incorrect reasons
1
Improvement: more quadrats
and
Reason: overcome random variation / (more) typical / (more) representative / (more)
reliable / repeatable
1
Improvement: larger quadrats or repeat when plants are bigger
and
Reason: less likely to miss plants
ignore accurate, valid, precise and fair
ignore anomalies
1
[6]

Q5.
(a) movement of particles from (an area of) high concentration to (an area of) low
concentration
allow movement of particles down a concentration gradient
do not accept along / across a concentration gradient
1

(b) oxygen
allow O2

Page 31 of 37
 carbon dioxide
allow CO2
in this order only
both needed for 1 mark
1

(c) less diffusion

allow less gas will enter / leave the blood
allow ecf from (b)
1

(because of the) reduced / smaller surface area

1

(d) (B) very low birth mass

1

(C) extremely low birth mass

1

(e) any one from:

• men would be included in the study (can’t be pregnant)
• children / older (post-menopausal) women would be included in the study
ignore reference to cost
1

(f) any three from:

• higher percentage of pregnant women have never smoked (compared with
non-pregnant women)
• higher percentage of pregnant women are ex-smokers (compared with non-
pregnant women)
• lower percentage of pregnant women currently smoke (compared with non-
pregnant women)
• in both pregnant and non-pregnant women, the highest percentage of women
have never smoked
allow converse throughout
allow appropriate use of correct figures throughout
3

(g) scatter graph

1

(h) B
1

(i) there is no correlation (between the variables)

allow (all) the points are widely scattered
allow idea that the person with the longest birth time does
not have the highest risk
1
[13]

Q6.
(a) large number – more representative and so more valid (mean can be calculated)
allow more reliable
1

Page 32 of 37
 random – avoid bias
1

(b) correct figures in table:

(3)
(8)
(16)
19
9
4
1
1

(c) all bars plotted correctly

± 1 mm
allow ecf from the table
1

(d) any three from:

• much overlap of values between the 2 shores

sheltered shore:
accept converse for exposed shore

• wider range or use of figures – e.g. approx 0.26 to 0.70 cf 0.21 to 0.55
• higher mode or use of figures – e.g. 0.41 to 0.45 cf 0.36 to 0.40
allow ecf for figures from (b)
• there are no limpets at 0.21 to 0.25
allow there are no limpets on exposed shore at 0.56 to 0.70
3

(e) sheltered – 0.47 or 0.466

1

exposed – 0.35 or 0.354

1

(f) radius = 2.48 cm

an answer of 38.6 / 38.62 / 38.64 scores 3 marks
1

(area = 3.14 × (2.48)2 =) 19.3 cm2

allow area calculated from incorrect radius
1

(force = 19.3 × 2 =) 38.6 (newtons)

or
(force = [3.14 × (2.48)2] × 2)
= 38.62 (newtons)
or
(force = [π × (2.48)2] × 2)
= 38.64 (newtons)
allow force calculated from 1 previous error
1

(g) any two from:

Page 33 of 37
 • foot may not be circular
• foot may be larger / smaller than outside of shell
• scientists’ value is approximate
• variation between limpets / described
e.g. re muscle development or greater ‘awareness’ of some
limpets
• variation in rock surface texture
2

(h) any three from:

• more force of waves to dislodge limpets
• lower height lowers exposure to waves
• wider foot gives greater grip
• those with this / these feature(s) pass on alleles / genes to offspring leading to
population of broad squat limpets
allow converse for sheltered shore throughout, if clearly
stated
3
[17]

Q7.
(a) an undifferentiated / unspecialised cell
1

that can differentiate / become / change into (many) other cell types
1

(b) (malignant tumours) invade / spread to other tissues via the blood (benign don’t)
or
(malignant tumours) form secondary tumours in other organs
ignore cancer unqualified
allow converse
allow metastasises
1

(c) mitosis
correct spelling only
1

(d) glucose
answers in any order
ignore sugar
1

protein / amino acids

1

(e) no need to wait for a donor

or
can be done immediately
1

(so) no risk of rejection

or
no need for immunosuppressant drugs
if no other marks awarded, allow for 1 mark idea of ethics

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 surrounding the use of tissue from another / dead person
1

(f) stent opens up the trachea

1

allowing air to flow through

or
allowing patient to breathe
1

(g) Level 3 (5-6 marks):

A judgement, strongly linked and logically supported by a sufficient range of correct
reasons, is given.

Level 2 (3-4 marks):

Some logically linked reasons are given. There may also be a simple judgement.

Level 1 (1-2 marks):

Relevant points are made. They are not logically linked.

Level 0
No relevant content

Indicative content

embryos advantages
• can create many embryos in a lab
• painless technique
• can treat many diseases / stem cells are pluripotent / can become any type of
cell (whereas bone marrow can treat a limited number)
embryos disadvantages
• harm / death to embryo
• embryo rights / embryo cannot consent
• unreliable technique / may not work

bone marrow advantages

• no ethical issues / patient can give permission
• can treat some diseases
• procedure is (relatively) safe / doesn’t kill donor
• tried and tested / reliable technique
• patients recover quickly from procedure
bone marrow disadvantages
• risk of infection from procedure
• can only treat a few diseases
• procedure can be painful

both procedures advantage

can treat the disease / problem

both procedures disadvantages
• risk of transfer of viral infection
• some stem cells can grow out of control / become
cancerous
[16]

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Q8.
(a) any two from:
• regular hand washing
or
use hand sanitiser / alcohol gel
• cover nose / mouth when coughing / sneezing
allow wear a face mask
• put used tissues (straight) in the bin
• don’t kiss uninfected people
allow isolate patient from others
or
don’t share cutlery / cups / drinks with uninfected people
• clean / disinfect / sterilise surfaces regularly
ignore responses referring to infected people
2

(b) any three from:

• stimulate (mouse) lymphocytes to produce antibody
for marking points 1 and 2 lymphocyte must be used at least
once
• combine (mouse) lymphocyte with tumour cell
or
(create a) hybridoma
• clone (hybridoma) cell
• (hybridoma) divides rapidly and produces the antibody
3

(c) any two from:

• (monoclonal) antibody binds to virus or antibody binds to antigen on surface
of virus
• (monoclonal) antibody is complementary (in shape) / specific to antigen (on
surface of virus)
• white blood cells / phagocytes kill / engulf the virus(es)
2

(d) as a control
or
to see / compare the effects of the treatment (vs. no treatment)
1

(e) (4.8 + 10.4) ÷ 2 ÷ 100 × 1500

or
(4.8 ÷ 100 × 750) + (10.4 ÷ 100 × 750)
1

114
an answer of 114 scores 2 marks
allow 228 for 1 mark
1

(f) (supports the conclusion because)

over double the number / % of patients (in the trial) were hospitalised with the
placebo (compared to MAB)
1

(does not support the conclusion because)

no information on patients not hospitalised / still unwell at home

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or
other factors may have affected those admitted to hospital
allow correct named factor e.g. age / gender / other illness
or
don’t know if it was a double blind trial
1
[12]

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