OCR GCSE Biology A: Genetic engineering and biotechnology in food production (J247) – Practice Questions

These are original questions written for Marlbridge, for revision and practice on this content. They are not reproduced past-paper questions, and they do not replicate the exam’s exact structure, question count or mark tariffs – examination boards hold copyright in their own papers. Use these alongside the official past papers from your board or school.

These questions are aligned to the OCR GCSE (9-1) Gateway Science Biology A (J247) specification, Version 4.0 (August 2026), for first assessment in 2018. They cover B6.2d, B6.2e, B6.2f and B6.2g. B6.2e is Higher Tier only, so questions 2 to 5 are labelled; the rest suit both tiers. All data are invented.

Links: study guide, revision notes, OCR GCSE Biology hub, printable checklist and the free 10-minute diagnostics.

Questions

1. (a) State what is meant by genetic engineering. [2] (b) Explain why a characteristic added to a crop by genetic engineering is passed on to its offspring. [1]

2. (Higher Tier only) Give the job of each of the following in the process of genetic engineering. [5] (a) restriction enzyme (b) sticky ends (c) ligase (d) plasmid (e) antibiotic resistance marker gene

3. (Higher Tier only) The statements below describe stages of making a recombinant plasmid, but they are in the wrong order.

A. Ligase joins the gene into the plasmid. B. The bacteria are grown on agar containing an antibiotic. C. The gene is cut from the donor DNA by a restriction enzyme. D. The recombinant plasmid is added to host bacteria. E. The plasmid is cut with the same restriction enzyme.

Write the letters in the correct order. [3]

4. (Higher Tier only) A technician treated bacteria with a plasmid carrying a resistance gene for antibiotic M. Equal volumes of culture were spread on four plates.

Plate	Bacteria	Antibiotic M in agar	Colonies
P	not exposed to plasmid	no	312
Q	not exposed to plasmid	yes	0
R	exposed to plasmid	yes	47
S	exposed to plasmid	no	305

(a) State what plate Q shows. [1] (b) State what plate S shows. [1] (c) Use plates R and S to calculate the percentage of bacteria that took up the plasmid. Give your answer to 3 significant figures. [2] (d) Explain why the colonies on plate R can grow, and why they do not prove that the wanted gene is present. [2]

5. (Higher Tier only) A restriction enzyme, enzyme B, cuts DNA wherever it finds the base sequence GGATCC and leaves sticky ends. A linear piece of DNA is 6000 base pairs long. It has the GGATCC sequence in two places, so enzyme B cuts it 1500 base pairs from the left end and again 4100 base pairs from the left end. The gene wanted is in the middle section. (a) Give the sizes of the three fragments. [2] (b) The plasmid has one GGATCC site. State what shape the plasmid has after enzyme B cuts it. [1] (c) Explain why the same enzyme must be used to cut the plasmid. [2]

6. A trial compared a conventional maize variety with an insect-resistant GM variety over 220 hectares each. The conventional variety gave 6.1 tonnes per hectare and needed 0.9 kg of insecticide per hectare. The GM variety gave 7.4 tonnes per hectare and needed 0.3 kg of insecticide per hectare. (a) Calculate the percentage increase in yield. Give your answer to 3 significant figures. [2] (b) Calculate the percentage reduction in insecticide use. Give your answer to 3 significant figures. [2] (c) Calculate the extra maize, in tonnes, produced by the GM variety over 220 hectares. [1] (d) Suggest one reason this trial cannot show whether GM maize harms wildlife. [1]

7. A student says, “GM crops always mean more pesticide is used.” Evaluate this statement using two types of GM crop. [4]

8. The table shows the mass of farmed salmon at different ages.

Age (months)	6	12	18	24	30
Conventional salmon (kg)	0.3	0.9	1.8	2.8	3.9
GM salmon with a growth hormone gene (kg)	0.6	1.8	3.4	4.3	4.4

(a) Calculate the mean growth rate of each type between 6 and 18 months, in kg per month. [2] (b) Describe what the data show about the GM salmon after 24 months. [1] (c) Explain how faster growth could help meet the demand for food. [1] (d) Suggest one risk of farming GM fish. [1]

9. Chymosin, an enzyme for cheese making, was once taken from calf stomachs. It can now be made by bacteria given the chymosin gene, grown in a fermenter. (a) Explain how the bacteria are able to make chymosin. [2] (b) A 5000 dm³ fermenter produces 0.8 g of chymosin per dm³. Calculate the mass in kg made in one batch. [2] (c) Give two advantages of making chymosin in bacteria rather than taking it from calves. [2]

10. The table shows the area of GM crops in one country, which has 36 million hectares of cropland.

Year	2012	2016	2022
GM crop area (million hectares)	2.5	4.5	9.0

(a) Calculate the area of GM crops in 2022 as a percentage of cropland. [1] (b) Calculate the percentage increase in GM crop area from 2012 to 2022. [2] (c) Calculate the mean increase per year for 2012 to 2016 and for 2016 to 2022, and state which period was faster. [2]

11. Rice has been modified to make beta-carotene, which the body can convert to vitamin A. It is proposed for a region where many children have vitamin A deficiency and where most farmers are poor. Evaluate the use of this GM rice. [8]

Answers

1. (a) It is a process that modifies the genome of an organism [1] to introduce desirable characteristics [1]. [2] (b) The new gene is part of the organism’s genome (DNA), so it is copied and inherited by offspring [1]. [1] Examiner insight: A definition usually gains credit when it names the genome and the purpose.

2. (a) Cuts DNA at a specific base sequence [1]. (b) Short unpaired ends left by the cut, which pair with complementary ends from the same enzyme [1]. (c) Joins the gene and the plasmid by sealing the backbones [1]. (d) A small circular loop of DNA that acts as the vector carrying the gene into the host bacterium [1]. (e) Allows only bacteria that took up the plasmid to survive on agar with the antibiotic, so they can be selected [1]. [5] Examiner insight: Give the job, not just a label: “joins the gene into the plasmid” answers the question.

3. Correct order: C, E, A, D, B. The gene is cut out first and the plasmid is cut next, in either order [1]. Ligase then joins them [1]. The plasmid is added to bacteria, and last the bacteria are grown on antibiotic agar [1]. [3] Examiner insight: The two cuts can be swapped; both must come before joining, and selection comes last.

4. (a) Untreated bacteria cannot survive antibiotic M, so colonies on plate R gained resistance [1]. (b) Bacteria exposed to plasmid still grow normally without antibiotic, so it gives the number that can grow [1]. (c) 47 / 305 × 100 [1] = 15.4% [1]. (d) The colonies carry the plasmid, which includes the resistance marker gene, so they survive the antibiotic [1]. The marker only shows the plasmid was taken up; it does not show that the wanted gene is inside it [1]. [6] Examiner insight: Link each control plate to what it rules out; “it is a control” alone is too vague.

5. (a) 1500 base pairs [1]; 4100 − 1500 = 2600 base pairs and 6000 − 4100 = 1900 base pairs [1]. [2] (b) One cut in a circle opens it into a single linear piece [1]. [1] (c) The same enzyme leaves sticky ends on the plasmid that are complementary to those on the gene [1], so they pair and ligase can join them; a different enzyme would leave ends that do not match [1]. [2] Examiner insight: Check the sizes add back to 6000 (1500 + 2600 + 1900).

6. (a) (7.4 − 6.1) / 6.1 × 100 [1] = 21.3% [1]. (b) (0.9 − 0.3) / 0.9 × 100 [1] = 66.7% [1]. (c) 1.3 × 220 = 286 tonnes [1]. (d) It measured only yield and insecticide use, not numbers or health of non-target insects, birds or soil organisms [1]. [6] Examiner insight: Divide by the original (conventional) value, not the new one.

7. Insect-resistant crops make their own toxin, so fewer insecticide sprays may be needed [1]. Herbicide-tolerant crops allow herbicide to be sprayed on the crop, and use may rise if weeds become resistant [1]. The effect depends on the trait [1], so “always” is not supported [1]. [4] Examiner insight: Test “always” with a counter-example: name both crops and give a different outcome for each.

8. (a) GM: (3.4 − 0.6) / 12 = 0.233 kg per month [1]. Conventional: (1.8 − 0.3) / 12 = 0.125 kg per month [1]. [2] (b) The mass levels off at about 4.3 to 4.4 kg, so it grows little after 24 months [1]. (c) Fish reach market size sooner, so more can be produced per year from the same tanks [1]. (d) Escaped fish could breed with wild fish and change wild populations [1]. [5] Examiner insight: Show the subtraction and division, and give units.

9. (a) The chymosin gene is inserted into the bacteria [1], which use it to make the protein as they grow [1]. [2] (b) 0.8 × 5000 = 4000 g [1] = 4.0 kg [1]. [2] (c) Any two: no calves need to be slaughtered [1]; supply can be steady and large [1]; the product is more uniform; it may suit vegetarians. [2] Examiner insight: Convert grams to kilograms by dividing by 1000.

10. (a) 9.0 / 36 × 100 = 25% [1]. (b) (9.0 − 2.5) / 2.5 × 100 [1] = 260% [1]. (c) 2012 to 2016: (4.5 − 2.5) / 4 = 0.5 million hectares per year [1]. 2016 to 2022: (9.0 − 4.5) / 6 = 0.75 million hectares per year, so the later period was faster [1]. [5] Examiner insight: The periods differ (4 and 6 years), so divide by years before comparing.

11. Points such as: Benefits: the rice makes beta-carotene, which the body converts to vitamin A, so it could reduce deficiency [1]. It improves diet quality where varied diets are costly [1]. If it yields as well as local rice, farmers need not change how they farm [1]. Risks and limits: long-term and environmental effects must be tested [1]. Genes could spread to other rice by pollen [1]. Labelling, consumer choice and who owns the technology are ethical and practical issues [1]. Seed cost matters to poor farmers [1]. Judgement: a clear conclusion that weighs the two sides, for example that benefit is high if testing shows safety and the rice is affordable [1]. [8] Examiner insight: Extended answers do best with balance and a stated judgement; benefits alone read as one-sided.

Where marks are usually lost

• Forgetting that the same restriction enzyme must cut both the gene and the plasmid.
• Writing that restriction enzymes join DNA, or that ligase cuts it; or saying the resistance gene helps the crop rather than marking bacteria.
• Dividing a percentage change by the new value.
• Omitting units, or not converting grams to kilograms.
• Listing only advantages when asked to evaluate, with no judgement at the end.

Next steps

• Re-read the study guide and use the revision notes for recall.
• Tick off each statement on the OCR GCSE Biology checklist and visit the course hub.
• Take all free 10-minute diagnostics to find other weak spots.
• Book a free trial class.

Official syllabus

OCR GCSE (9-1) Gateway Science Biology A (J247), specification Version 4.0 (August 2026), for first assessment in 2018, published by OCR. Statements B6.2d to B6.2g, topic B6.2 Feeding the human race.