Food security, farming, fisheries and biotechnology – GCSE Biology exam questions with mark scheme

1Grade 1–3FoundationTriple only4 marks

The number of people in the world is increasing. Scientists are worried about food security.

(a) What is meant by food security? [1]

(b) Which two of the following are threats to food security?

Tick (✓) two boxes. [2]

☐ A fall in the birth rate
☐ New pests that attack crops
☐ Using fishing quotas
☐ Rising prices of fertilisers and animal feed
☐ Growing mycoprotein in fermenters

Suggest one way the war could reduce food security. [1]

(a) having enough (safe / nutritious) food to feed a population
allow everyone has access to enough food (to be healthy)
ignore food is safe to eat / not contaminated, unqualified(1)
(b) New pests that attack crops ✓(1)
(b) Rising prices of fertilisers and animal feed ✓
if more than two boxes are ticked, deduct one mark for each extra tick (minimum 0)(1)
(c) any one from:
• farmland / crops destroyed
• farmers are unable to plant / grow / harvest crops (e.g. they have to fight or flee)
• transport / export of food (e.g. wheat) is blocked or disrupted, so less food reaches people / other countries
• food prices rise so people cannot afford food
ignore 'people die' unqualified(1)
Answer: (a) Having enough food to feed a population. (b) New pests that attack crops; rising prices of fertilisers and animal feed. (c) e.g. crops destroyed or exports of wheat blocked.
Examiner tip: For (a) say "enough food for the population" — writing only "food that is safe" misses the idea of quantity.

2Grade 1–3FoundationTriple only5 marks

Mycoprotein is a protein-rich food that is suitable for vegetarians.

The diagram shows a fermenter used to make mycoprotein.

(a) Name the microorganism that is grown to make mycoprotein. [1]

(b) Sterile air is bubbled into the fermenter.

Explain why the microorganism needs air. [2]

Explain why the water jacket is needed. [2]

(a) Fusarium
allow phonetic spelling, e.g. fusarium / fusareum
do not accept 'fungus' alone / yeast / bacteria(1)
(b) oxygen (in the air) is needed for aerobic respiration
do not accept 'air is needed for respiration' without oxygen or aerobic(1)
(b) (respiration) releases / transfers energy for growth (of the fungus)
allow so more fungus / mycoprotein is produced
do not accept 'produces energy'(1)
(c) the fungus releases heat / thermal energy from respiration
allow the fermenter would overheat(1)
(c) to keep the temperature at the optimum (for growth / for enzymes)
allow so enzymes are not denatured / so the fungus is not killed
ignore 'to keep it cool' unqualified(1)
Answer: (a) Fusarium (b) Oxygen for aerobic respiration, which releases energy for growth. (c) Respiration releases heat; the jacket keeps the temperature at the optimum so enzymes are not denatured.
Examiner tip: "Energy is produced" never scores — respiration releases or transfers energy.

3Grade 4–5Triple only6 marks

A farmer compared two ways of rearing chickens for meat.

Intensive: chickens kept indoors in a heated shed with little space to move.
Free-range: chickens kept outdoors in a large field.

The table shows the results for one chicken from each group over 6 weeks.

	Intensive	Free-range
Energy in food eaten in kJ	52 000	60 000
Energy transferred to chicken biomass in kJ	9 360	7 200
Efficiency of energy transfer in %	18	X

(a) Calculate value X in the table. [2]

(b) Explain why the efficiency of energy transfer is higher for the intensively reared chickens. [3]

(a) 7200 ÷ 60 000 (× 100)(1)
(a) 12 (%)
allow 0.12 for 1 mark only(1)
(b) (intensive chickens) move less, so less energy is used in respiration for (muscle) movement(1)
(b) (intensive chickens) are kept warm, so less energy is transferred (as heat) to the surroundings / used to keep body temperature constant(1)
(b) so more energy (from food) is available for growth / is stored in biomass
allow so they gain more mass from the same food(1)
(c) any one from:
• breed / type of chicken
• age / starting mass of chickens
• type of food
• time / length of the trial
ignore 'amount of food' (this is different in the table)
ignore 'same chicken'(1)
Answer: (a) X = 12% (b) Less movement and kept warm, so less energy used in respiration / lost as heat; more energy goes into biomass. (c) e.g. same breed of chicken.
Examiner tip: Link each farming condition to energy: "less movement" alone is not enough — say less energy is used in respiration, so more is stored as biomass.

4Grade 4–5Triple only5 marks

Cod is a fish caught for food in the North Sea.

The graph shows the mass of adult cod in one area of the sea between 1990 and 2020. Fishing quotas were introduced in 2005.

(a) Calculate the percentage decrease in the mass of adult cod between 1990 and 2005. [2]

(b) Explain how fishing quotas helped the cod population to increase after 2005. [2]

Suggest one reason why the population had not fully recovered. [1]

(a) (150 − 50) ÷ 150 (× 100) or 100 ÷ 150 (× 100)(1)
(a) 67 (%)
allow 66.7 / 66.67 (%)
do not accept 200 (%) (dividing by 50)(1)
(b) quotas limit the number / mass of fish that can be caught(1)
(b) so more fish survive to breed / reproduce
allow more young fish are produced(1)
(c) any one from:
• cod take several years to grow / reach breeding age
• some illegal fishing / overfishing still took place
• other factors, e.g. a change in sea temperature / less food (prey) for cod
• young cod / small fish still caught (e.g. as by-catch)(1)
Answer: (a) 67% (b) Quotas limit the number of fish caught, so more survive to breed. (c) e.g. cod take years to reach breeding age.
Examiner tip: Always divide the change by the original value (150), not the final value.

5Grade 6–7HigherTriple only6 marks

Human insulin is made by genetically modified bacteria grown in large fermenters.

A fermenter is started with $2.0 \times 10^{5}$ bacteria. The mean division time of the bacteria is 25 minutes.

(a) Calculate the number of bacteria in the fermenter after 5 hours.

Assume all the bacteria survive and divide. Give your answer in standard form. [3]

(b) In reality, the bacteria cannot keep dividing every 25 minutes for many days.

Suggest two reasons why. [2]

Suggest why the insulin must be purified. [1]

(a) number of divisions = (5 × 60) ÷ 25 = 12(1)
(a) $2.0 \times 10^{5} \times 2^{12}$ or $2.0 \times 10^{5} \times 4096$(1)
(a) $8.2 \times 10^{8}$ (bacteria)
allow $8.192 \times 10^{8}$ / $8.19 \times 10^{8}$
allow 819 200 000 for 2 marks only (not in standard form)(1)
(b) any two from:
• glucose / nutrients run out
• toxic waste products build up
• oxygen runs out / becomes limited
• space becomes limited
• pH / temperature changes (from optimum)(1)
(b) second reason from the list(1)
(c) to remove bacteria / other substances that could cause an immune response / infection / harm the patient
allow so the insulin is safe to inject
ignore 'to make it clean' unqualified(1)
Answer: (a) $8.2 \times 10^{8}$ bacteria (b) e.g. nutrients run out; toxic waste builds up. (c) Remove bacteria or other substances that could harm the patient.
Examiner tip: Work out the number of divisions first (12), then multiply by $2^{12}$ — not by 12 × 2.

6Grade 4–5Triple only5 marks

In some countries, rice is the main food. Many children in these countries do not get enough vitamin A, which can cause blindness.

Scientists have produced golden rice. Genes from other organisms were added to rice plants so that the rice grains make beta-carotene. The body converts beta-carotene into vitamin A.

(a) Golden rice is a genetically modified (GM) crop.

What is meant by a GM crop? [1]

(b) A young child needs 400 µg of vitamin A each day.

100 g of cooked golden rice provides 160 µg of vitamin A.

Calculate the mass of cooked golden rice the child would need to eat each day to get all of their vitamin A from rice. [2]

Give two reasons why. [2]

(a) a crop / plant whose genes have been changed by adding a gene from another organism / species
allow a crop that has had its genome changed by genetic engineering
ignore 'genetically modified' (given in stem)(1)
(b) 400 ÷ 160 (= 2.5) or 160 ÷ 100 = 1.6 µg per g seen(1)
(b) 250 (g)(1)
(c) any two from:
• genes / pollen may spread to wild plants / other crops
• may harm populations of wild flowers / insects / reduce biodiversity
• long-term effects on human health not fully known
• seed may be expensive / controlled by large companies, so poor farmers cannot afford it
• people should eat a more varied diet / vitamin A tablets instead
ignore 'it is unnatural' / 'playing God' unqualified(1)
(c) second reason from the list(1)
Answer: (a) A crop with a gene from another organism added. (b) 250 g (c) e.g. genes could spread to wild plants; long-term health effects unknown.
Examiner tip: In (b) the 160 µg is per 100 g, so 400 ÷ 160 gives the number of 100 g portions (2.5) — multiply by 100 to get grams.

7Grade 4–5Triple only7 marks

The table shows the world human population in 2020 and the predicted population in 2050.

Year	World population in billions
2020	7.8
2050 (predicted)	9.7

(a) Calculate the percentage increase in world population from 2020 to 2050.

Give your answer to 2 significant figures. [2]

(b) As people become richer, they often eat more meat and less plant food.

Explain why this change in diet is a threat to food security. [3]

Suggest how this could reduce food security in poorer countries. [2]

(a) (9.7 − 7.8) ÷ 7.8 (× 100) or 1.9 ÷ 7.8 (× 100)(1)
(a) 24 (%)
allow 24.4 / 24.36 for 1 mark only (not 2 s.f.)(1)
(b) (farm) animals are at a higher trophic level / meat is a step further along the food chain(1)
(b) energy / biomass is lost at each trophic level, e.g. through respiration / movement / heat / waste (faeces, urine)
allow only about 10% of energy is transferred(1)
(b) so more land / more crops are needed to produce the same amount of food (from meat) than if people ate plants directly
allow crops are fed to animals instead of people(1)
(c) farmers buy / use less fertiliser, so crops have less nitrate / mineral ions(1)
(c) so crop yields fall / less food is produced
allow food becomes more expensive so people cannot afford enough(1)
Answer: (a) 24% (b) Animals are at a higher trophic level; energy is lost at each level, so more crops/land are needed per unit of food. (c) Less fertiliser used → lower yields → less food.
Examiner tip: In (b) use the trophic-level idea: "meat needs more land" only scores if you say why — energy is lost at each level.

8Grade 8–9HigherTriple only6 marks

A farmer is deciding whether to rear pigs intensively (indoors, in small pens kept at a warm temperature) or free-range (outdoors in fields).

The table gives information about the two methods.

	Intensive	Free-range
Time for pig to reach slaughter mass in weeks	22	28
Food eaten per pig to reach slaughter mass in kg	250	310
Space per pig in m²	0.8	50
Cost to produce 1 kg of meat in £	1.60	2.30
Use of antibiotics	high	low

Evaluate the two methods of rearing pigs.

Use information from the table and your own knowledge. [6]

Intensive — for: pigs reach slaughter mass 6 weeks faster(1)
intensive pigs eat 60 kg (about 19%) less food to reach slaughter mass, so energy transfer is more efficient(1)
less movement means less energy used in respiration; warm pens mean less energy lost as heat to the surroundings / for keeping warm(1)
cheaper meat (£0.70 less per kg), so more people can afford protein / helps food security(1)
much less land used per pig, so more land left for crops / habitats(1)
Intensive — against: ethical objections — animals cannot move freely / show natural behaviour / may be stressed(1)
disease spreads quickly in crowded conditions, so more antibiotics are used(1)
overuse of antibiotics can lead to antibiotic-resistant bacteria(1)
heating sheds needs energy / fuel, which costs money and may release carbon dioxide(1)
Free-range: better animal welfare / natural behaviour; less disease and antibiotic use; but slower growth, more food and land needed, meat more expensive(1)
Judgement: a reasoned conclusion, e.g. intensive is better for producing cheap food / food security, but free-range is better for welfare and reducing antibiotic resistance(1)

Level	Marks	What it looks like
Level 3	5–6	Considers advantages and disadvantages of both methods, using data from the table and explaining at least one point scientifically (e.g. energy transfer or antibiotic resistance), and reaches a reasoned conclusion consistent with the points made.
Level 2	3–4	Gives advantages and disadvantages, with some use of the data and some scientific explanation, but the evaluation is unbalanced or the conclusion is missing or not supported.
Level 1	1–2	Gives simple, mostly unlinked points about one or both methods (e.g. copies values from the table) with little or no explanation.
No relevant content	0	Nothing worthy of credit.

Answer: An evaluation weighing up both methods using the data (faster growth, 60 kg less food, cheaper meat, less land for intensive; welfare, lower disease and antibiotic use for free-range), explaining energy transfer, and ending with a justified judgement.
Examiner tip: "Evaluate" needs a judgement — finish with a conclusion that says which method is better and why, linked to the data.

9Grade 6–7Triple only6 marks

The table compares beef and mycoprotein.

	Beef	Mycoprotein
Land needed to produce 1 kg of food in m²	164	6
Protein in g per 100 g of food	26	11
Fat in g per 100 g of food	15	3

(a) How many times more land is needed to produce 1 kg of beef than 1 kg of mycoprotein? [1]

(b) A person wants to get the same mass of protein from mycoprotein as from 1 kg of beef.

Calculate the area of land needed to produce this mycoprotein. Give your answer to 3 significant figures. [3]

(a) 27 (times)
allow 27.3 / 27.33(1)
(b) mass of mycoprotein needed = 26 ÷ 11 = 2.36 (kg)
allow 260 ÷ 110 or 2.4 (kg)(1)
(b) 2.36 × 6(1)
(b) 14.2 (m²)
14.18 (not given to 3 s.f.) scores 2 marks
an answer of 14.4 (from rounding to 2.4 kg too early) scores 2 marks(1)
(c) cattle eat plants / crops, so (much) more plant material must be grown (on land) to feed them
allow cattle are at a higher trophic level(1)
(c) energy / biomass is lost between trophic levels, e.g. in respiration / movement / heat / waste
allow Fusarium is grown in fermenters (on glucose syrup), which take up little space(1)
Answer: (a) 27 times (b) 14.2 m² (c) Cattle are fed on crops; energy is lost at each trophic level so far more plant material (and land) is needed.
Examiner tip: In (b) adjust for protein content first: you need 26 ÷ 11 = 2.36 kg of mycoprotein, not 1 kg.

10Grade 8–9HigherTriple only7 marks

A fisheries authority tested nets with different mesh sizes for catching haddock. Haddock below breeding size are classed as immature.

The table shows the results.

Mesh size in mm	Number of haddock caught in a test trawl	Number of immature haddock caught	Mean mass of fish landed per fishing trip in tonnes
80	1240	770	9.5
100	1010	412	8.0
120	820	152	6.1
140	540	31	3.9

The authority wants fewer than 20% of the haddock caught to be immature.

(a) Determine the smallest mesh size that meets this target. Use calculations to support your answer. [2]

(b) Calculate the percentage decrease in the mean mass of fish landed per trip if fishing boats change from 80 mm to 120 mm mesh. [2]

(d) Explain how controlling the mesh size of nets helps to keep haddock stocks sustainable. [2]

(a) percentages calculated for at least the 100 mm and 120 mm nets: 412 ÷ 1010 × 100 = 40.8 (%) and 152 ÷ 820 × 100 = 18.5 (%)
allow 41% and 19% / 18.5%(1)
(a) 120 (mm)
answer only with no supporting calculation = 0 marks(1)
(b) (9.5 − 6.1) ÷ 9.5 (× 100) or 3.4 ÷ 9.5 (× 100)(1)
(b) 36 (%)
allow 35.8 / 35.79 (%)(1)
(c) the mass of fish landed would be much lower / falls to 3.9 tonnes, so fishermen earn less / less food produced
allow 120 mm already meets the target, so a larger mesh is not needed(1)
(d) young / immature / small fish escape through the larger mesh(1)
(d) so they survive to reach breeding age / reproduce, replacing the fish that are caught
allow so the population does not fall / fish are not caught faster than they can reproduce(1)
Answer: (a) 120 mm (100 mm = 40.8%, 120 mm = 18.5%) (b) 36% (c) Catch would fall to 3.9 t, reducing income/food. (d) Immature fish escape and survive to breed.
Examiner tip: "Determine… use calculations" means a bare answer of 120 mm scores nothing — show the percentage for each net you compare.

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