OCR GCSE Biology A: Stem cells, gene technology and genomics in medicine (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 cover statements B6.3v, B6.3w and B6.3x of OCR GCSE (9-1) Gateway Science Biology A (J247), specification Version 4.0 (August 2026), for first assessment in 2018. None of these statements is marked Higher Tier only in the specification text. Learn the content first from the study guide and the revision notes. The OCR GCSE Biology hub, the printable checklist and the free diagnostics show where to focus.

Questions

1. Explain why donor stem cells may be rejected by the person who receives them. [3]

2. Describe two ways of reducing the chance that transplanted cells are rejected. [2]

3. A hospital treats 150 patients with donor stem cells from umbilical cord blood. In 36 patients, donor white blood cells attack the patient’s own tissues.

(a) Calculate the percentage of patients affected. [2] (b) Name this condition and explain why it happens. [2]

4. Therapeutic cloning can produce embryonic stem cells for a patient.

(a) Describe how the cells are produced. [3] (b) Explain why these cells should not be rejected by the patient. [2]

5. A surgeon records rejection of skin grafts. Without a drug, 14 of 80 grafts were rejected. With an immunosuppressant, 6 of 75 grafts were rejected.

(a) Calculate the percentage rejected in each group. [3] (b) Evaluate the use of the immunosuppressant. [3]

6. Human insulin can be made by bacteria.

(a) Describe how bacteria are made to produce human insulin. [3] (b) Give one benefit of this method compared with extracting insulin from animal pancreases. [1]

7. In a gene therapy trial for a blood disorder, 25 patients are treated. After one year, 18 have improved and 3 have a serious complication.

(a) Calculate the percentage who improved and the percentage with a serious complication. [2] (b) The working allele was delivered by a modified virus. State the name for this carrier and give one risk of using it. [2] (c) Discuss whether this therapy should be offered to a child with a fatal form of the disorder. [2]

8. A scientist proposes gene therapy on early embryos.

(a) Explain why this raises different ethical issues from gene therapy on a patient’s body cells. [2] (b) Give one other issue, not about inheritance, that affects who can use gene therapy. [2]

9. In a country, 9% of people develop disease P in their lifetime. Of people with allele B, 45% do. In a town of 50 000 people, 1 in 250 carry allele B.

(a) Calculate the number of carriers in the town. [1] (b) Calculate how many carriers are expected to develop disease P. [1] (c) Calculate how many extra cases this is compared with carriers who had the average risk. [2] (d) A carrier says, “So I will definitely get disease P.” Explain why this is wrong. [2]

10. A drug is tested on 400 patients. 150 have a genetic marker and 250 do not. 90 patients with the marker respond to the drug. 20 patients without the marker respond.

(a) Calculate the percentage of patients who respond in each group, and overall. [3] (b) Explain how these results support testing patients before prescribing the drug. [2]

11. A health service is considering sequencing the genome of every adult to predict disease risk.

(a) Discuss the benefits and problems of this plan and give a conclusion. [6] (b) Suggest two pieces of information that would help the health service decide. [2]

Answers

1. Donor cells have antigens on their surface that differ from the recipient’s [1]. The recipient’s immune system (lymphocytes) recognises them as foreign [1]. It attacks and destroys the donor cells [1]. [3] Examiner insight: An answer that says only “the body does not like it” gains little credit. Name the surface antigens, the recognition as foreign and the attack in order.

2. Match the tissue type of donor and recipient, for example by using a close relative [1]; give immunosuppressant drugs [1]. Other valid methods: use the patient’s own stem cells, or use therapeutic cloning. [2] Examiner insight: Two different methods are needed. Saying “match it” and then “choose a similar donor” is one idea written twice.

3. (a) 36 ÷ 150 × 100 [1] = 24% [1] (b) Graft-versus-host disease [1]. The donor white blood cells recognise the patient’s tissues as foreign and attack them [1]. [4 in total across (a) and (b)] Examiner insight: In (b), say that the donor cells do the attacking. Describing rejection of the donor cells by the patient is the opposite direction and answers a different question.

4. (a) The nucleus is taken from one of the patient’s body cells [1]. It is put into an egg cell whose nucleus has been removed [1]. The cell is stimulated to divide and form an early embryo, from which embryonic stem cells are collected [1]. (b) The cells are genetically identical to the patient, so they carry the patient’s own antigens [1]. The immune system therefore does not treat them as foreign [1]. [5 in total across (a) and (b)] Examiner insight: Link “genetically identical” to “same antigens” before stating the outcome. Stopping at “identical” leaves the reasoning incomplete.

5. (a) Without the drug: 14 ÷ 80 × 100 [1] = 17.5% [1]. With the drug: 6 ÷ 75 × 100 = 8% [1]. (b) The drug cuts rejection from 17.5% to 8%, which is a large reduction [1]. However, immunosuppressants weaken the immune system, so patients are at higher risk of infection [1]. Because the groups differ in size and the trial is small, a larger trial is needed before concluding the drug is safe and effective [1]. [6 in total across (a) and (b)] Examiner insight: An evaluation needs a figure from the data, a drawback and a limit on the evidence. A bare “it works” will not cover all of those.

6. (a) The human insulin gene is identified and cut out [1]. It is inserted into bacteria, for example into a plasmid [1]. The bacteria are grown in large fermenters, make insulin, and the insulin is collected and purified [1]. (b) Any one of: larger, more reliable supply; no need for animal pancreases; the insulin is identical to human insulin [1]. [4 in total across (a) and (b)] Examiner insight: Mention where the gene ends up (the bacteria) and what happens next (growth and collection). Many answers give only the first step.

7. (a) Improved: 18 ÷ 25 × 100 = 72% [1]. Serious complication: 3 ÷ 25 × 100 = 12% [1]. (b) The carrier is a vector [1]. A risk: it may insert the allele in the wrong place and cause cancer, or trigger an immune response [1]. (c) Benefit: the therapy helped most patients, and without treatment the child faces a fatal outcome [1]. Risk: 12% had a serious complication and long-term effects are unknown, but where the disorder is fatal and no other treatment works, the risk may be acceptable [1]. [6 in total across (a) to (c)] Examiner insight: A “discuss” answer is stronger when it uses the supplied percentages and reaches a reasoned view. It should not stop at listing points.

8. (a) Changes in embryo cells would be passed on to the person’s children and later generations [1]. Those future people cannot consent to the change, whereas an adult patient can [1]. (b) Gene therapy is very expensive [1]. So only wealthy patients or well-funded health services could use it, which raises a fairness issue [1]. [4 in total across (a) and (b)] Examiner insight: Each ethical point needs its reason. “It is unfair” gains less than saying who is left out and why.

9. (a) 50 000 ÷ 250 = 200 carriers [1] (b) 45% of 200 = 90 [1] (c) At the average risk, 9% of 200 = 18 [1]. Extra cases = 90 − 18 = 72 [1] (d) The risk is 45%, so 55% of carriers do not develop the disease [1]. A genetic risk is a probability, and other factors such as environment and lifestyle also affect whether it develops [1]. [6 in total across (a) to (d)] Examiner insight: Show each step in order, writing the carrier count before using it. Clear working makes your reasoning easy to follow and helps you spot slips.

10. (a) With marker: 90 ÷ 150 × 100 = 60% [1]. Without marker: 20 ÷ 250 × 100 = 8% [1]. Overall: 110 ÷ 400 × 100 = 27.5% [1]. (b) The drug works for far more patients with the marker (60%) than without it (8%) [1]. Testing would let doctors give the drug to those likely to respond, and avoid side effects and cost for those unlikely to benefit [1]. [5 in total across (a) and (b)] Examiner insight: Quote both group figures and compare them. The overall figure on its own hides the difference between the groups.

11. (a) Benefit: finds raised risks early, so screening or lifestyle changes can start [1]. Benefit: results can guide drugs targeted to the patient’s genome, or help relatives learn their own risk [1]. Problem: results give risks, not certainties, so people may be worried unnecessarily or falsely reassured [1]. Problem: privacy, and misuse of data by insurers or employers [1]. Further valid points: cost and counselling needs, people not wanting to know. A balanced conclusion [1], for example that the plan should go ahead only with protected data and the choice to opt out, with a reason [1]. (b) The cost compared with the number of cases prevented [1]. How reliably the tests predict disease [1]. Other valid points: how many people would accept testing, and whether laws can protect the data. [8 in total across (a) and (b)] Examiner insight: Six-mark “discuss” answers usually gain credit for balance and a reasoned conclusion. Keep points distinct, because repeating the same point in new words adds nothing.

Where marks are usually lost

• Writing “rejected” without antigens, recognition as foreign and attack.
• Mixing up rejection with graft-versus-host disease.
• Calling immunosuppressants harmless, with no mention of infection.
• Describing insulin production without saying the gene goes into bacteria.
• Treating a genetic risk as a certainty.
• Giving one side only in a “discuss” or “evaluate” answer.
• Quoting percentages without naming the group they apply to.
• Stating an ethical view with no reason behind it.

Next steps

• Revise from the revision notes and re-read the study guide.
• See the OCR GCSE Biology hub and the printable checklist.
• Take one of our free 10-minute diagnostics.
• 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 B6.3v, B6.3w and B6.3x.