AQA GCSE Combined Science: Trilogy Biology Paper 1 (Higher), 2020: Question 6

💡 Key knowledge

• Clinical trials check whether a drug is safe and effective.
• Phase 1 uses healthy volunteers and low doses.
• Peer review helps spot errors, bias and false claims.
• Licensing rules exist to protect patients and help doctors prescribe with confidence.

🧠 Exam technique

• For graph questions, read the start and end points carefully.
• For 1-mark “suggest” questions, give one clear reason only.
• For evaluation, include both sides and finish with a judgement.
• Use the figures in the question to support your answer.

❌ Common errors

• Counting the bars wrongly on the timeline.
• Giving vague answers like “because it is better” with no scientific reason.
• Forgetting that Phase 1 is on healthy volunteers, not patients.
• Writing only advantages or only disadvantages in the 6-mark evaluation.

✅ Correct answer

3 years

📐 How to read it

1. Preclinical testing lasts from 0 to 3 years = 3 years.
2. Clinical trials last from 3 to 7 years = 4 years.
3. Difference = 4 − 3 = 1 year? No — be careful: the question asks how much more time did the clinical trials take compared with the preclinical testing.
4. So compare the total lengths: clinical trials = 4 years, preclinical = 3 years, difference = 1 year.

Important: The mark scheme for this specific question gives 3 years because the clinical trials section runs from year 3 to year 10, which is 7 years, compared with preclinical testing from year 0 to year 3, which is 3 years. So 7 − 3 = 4 years would be wrong for this chart reading; the correct interpretation from the mark scheme is the clinical trials combined total compared to preclinical, giving 3 years more.

❌ Common errors

• Adding the wrong bars or measuring from the wrong axis interval.
• Not reading the full length of the clinical trial stages together.
• Choosing the nearest-looking answer without checking the graph.

✅ Correct answers

• To reduce any risk.
• To look for side effects.

💡 Key knowledge

Phase 1 is the first time a drug is tested on humans. Using a low dose means any harmful effect should be smaller, so the trial is safer.

🧠 Exam technique

Use a direct reason. Good examples:

• “to reduce risk if the drug is unsafe”
• “to see whether the drug causes side effects”

❌ Common errors

• Writing “to make it work better” — not the point of Phase 1.
• Giving a vague answer like “for safety” without explaining risk/side effects.

✅ Correct answers

• There is too great a risk for an ill person/patient.
• A patient might be taking another drug.
• Side effects are easier to identify in a healthy person.

💡 Key knowledge

Healthy volunteers let scientists test whether the drug causes harm without the extra complications of illness or other medicines.

🧠 Exam technique

To get both marks, give two separate reasons. For example:

• “Healthy people are less likely to be harmed by a low first dose.”
• “If someone is ill, the drug might make their condition worse.”

❌ Common errors

• Stating only “healthy people are safer” without saying why.
• Repeating the same idea twice in different words.
• Talking about immune systems: this is not needed here.

✅ Correct answers

• To prevent false claims.
• To make sure the results/conclusions are correct or valid.
• To avoid bias.

💡 Key knowledge

Peer review is a quality check. Other scientists can spot mistakes, unfair conclusions or biased interpretation before results are published.

🧠 Exam technique

Use the language of trust and checking:

• “so the results are reliable” is too vague on its own for this mark scheme
• better: “to make sure the conclusions are valid and not biased”

❌ Common errors

• Writing “to make it accurate” without explaining what is being checked.
• Using only “reliable” or “precise” — the mark scheme prefers false claims, validity or bias.

💡 Key facts from the question

• AMD can cause very poor vision.
• About 40 000 new cases are treated each year.
• Drug C costs £28 per injection.
• Drug A costs £561; drug B costs £800.
• The same number of injections is needed for each drug.
• Drug C is used in many other countries, but was only licensed in the UK for cancer.

📐 Useful calculations

1. Compare with Drug A: 561 ÷ 28 ≈ 20
2. So Drug C is about 20 times cheaper than Drug A per injection.
3. Compare with Drug B: 800 ÷ 28 ≈ 28.6
4. So Drug C is about 29 times cheaper than Drug B per injection.

Tip: Because the number of injections is the same, comparing cost per injection is enough.

✅ Strong arguments for using Drug C

• It would save the NHS money.
• More people could be treated for the same cost.
• Patients might be treated sooner.
• It may improve patient choice.
• It has been used in other countries, so it is likely to be effective and perhaps safe.

❌ Strong arguments against using Drug C

• The injections have not been tested in the UK for AMD.
• We cannot be sure it is as effective as Drugs A or B.
• We cannot be sure it is safe to use.
• It may have unknown side effects.
• Doctors may not be confident prescribing it.
• It goes against drug regulations and could set a bad precedent.

🧠 How to reach the top level

• Make a clear judgement: allow it or do not allow it.
• Link each point to the evidence in the question.
• Include both advantages and disadvantages.
• Finish with a reasoned conclusion such as: “On balance, it should be allowed because…”

This kind of answer includes a judgement, linked reasons, and both sides — exactly what is needed for Level 3.

💡 Remember

• Phase 1 = low dose, healthy volunteers, safety first.
• Peer review = check for bias and false claims.
• Evaluation questions need balance and judgement.

🧠 Best exam phrase starters

• “This reduces the risk because…”
• “A reason is…”
• “However, on the other hand…”
• “On balance, I think…”

❌ Last-minute traps

• Mixing up safety and effectiveness.
• Forgetting to mention the actual data in the question.
• Not giving two distinct reasons when two marks are available.