AQA GCSE Combined Science: Trilogy Biology Paper 1 (Foundation), 2020: Question 2

💡 Key knowledge

• New drugs are tested first in the lab, then on healthy volunteers, then on patients.
• Preclinical testing uses cells, tissues or live animals.
• Clinical trials test safety, dosage and effectiveness.
• A placebo does not contain the active drug.
• In a double-blind trial, neither the patients nor the doctors know who gets the real drug.
• When comparing medicines, only one variable should change.
• Graph questions often reward careful reading of values and direct comparisons.

🧠 Exam technique

• For 1-mark questions, give one precise statement only.
• Use wording close to the mark scheme where possible: safe to use , does not contain the active ingredient , neither doctors nor patients know .
• On graph questions, quote data if you can.
• For “give two variables” questions, choose things that are clearly controlled in both groups.

✅ Correct answer

Any one of:

• live cells
• live tissues
• live animals

💡 Key knowledge

Before testing drugs on humans, scientists do preclinical testing to look for toxicity, efficacy and the best dose.

❌ Common errors

• Saying “humans” — that is clinical testing, not preclinical.
• Giving equipment instead of what is being tested on.

✅ Correct answer

7 years

📐 How to read it

1. Look at the bar for the drug in Figure 2.
2. Read the start time and end time from the x-axis.
3. Calculate duration = end − start.
4. The total is 7 years.

❌ Common errors

• Giving the finishing year instead of the length of time.
• Miscounting the intervals on the axis.

✅ Correct answer

To see if the drug is safe to use.

💡 Key knowledge

Phase 1 trials are mainly about safety. Low doses reduce risk while scientists watch for side effects.

🧠 Exam technique

If the question asks why healthy adults are used first, the safest exam wording is about safety, not cure or effectiveness.

✅ Correct answer

A tablet that does not contain the drug / active ingredient.

💡 Key knowledge

A placebo is used for comparison so scientists can see whether the real drug actually works better than no active treatment.

❌ Common errors

• Saying “a weaker drug” — a placebo has no active ingredient.
• Saying “a control variable” — placebo is part of the trial design, not a variable.

✅ Correct answer

Not the patients or the doctors.

🧠 Exam technique

For double-blind, learn the exact phrase: neither the patients nor the doctors know.

💡 Key knowledge

This reduces bias when results are recorded and judged.

✅ Correct answers

Any two from:

• age
• gender
• body mass
• number of children in each group / 100 in each group
• time after taking medicine when temperature was measured

💡 Key knowledge

A control variable is something kept the same so the comparison is fair.

The mark scheme also allows similar ideas such as all children starting with a high body temperature, or dose of medicine.

But “temperature” on its own is too vague and would not be credited.

🧠 Exam technique

Pick variables that are clearly stated in the method. This is safer than inventing your own.

Strong exam answers here are short and specific, for example:

1. Age of children
2. Time after taking the medicine when temperature was measured

❌ Common errors

• Writing the independent variable, such as type of medicine.
• Writing “temperature” without saying starting temperature or time temperature was measured.
• Giving just one variable when two are needed.

✅ Correct answer

Any one from:

• It would be unethical not to treat ill children.
• The children were ill so had to be treated.
• Children may become more ill if no drug is given.

💡 Key knowledge

Ethics matter in clinical trials. If patients are sick, leaving them untreated can be unsafe and unfair.

🧠 Exam technique

Use the word unethical when appropriate — examiners like precise scientific vocabulary.

✅ Correct answer

37.4 °C

📐 Reading the graph

1. Find the horizontal line labelled as normal body temperature.
2. Read its value from the y-axis.
3. The value is 37.4 °C.

❌ Common errors

• Writing 37 °C from memory instead of reading the graph.
• Missing the decimal place.

✅ Correct answers

Any two from:

• Ibuprofen reduced body temperature faster.
• Ibuprofen decreased body temperature more.
• Ibuprofen reduced body temperature to normal / 37 °C.
• Ibuprofen maintained normal body temperature / 37 °C for longer or for several hours.

💡 Key knowledge

This is an AO3 graph interpretation question. You must compare the two lines, not just describe one line.

Top answers use comparative language such as faster, more, to normal temperature, and for longer.

🧠 Exam technique

A strong 2-mark answer could be:

1. Ibuprofen lowered the children’s temperature faster.
2. It brought temperature down to normal and kept it there for longer.

This scores well because it gives two clear comparisons.

❌ Common errors

• Saying only “ibuprofen worked better” with no evidence.
• Describing one line without comparing it to the other medicine.
• Using vague phrases like “it was lower” without saying faster, more, or to normal.

💡 Where students gained marks

• Using exact trial vocabulary: placebo, double-blind, safe, control variable.
• Reading graph values carefully instead of using remembered “facts” like 37 °C.
• Making direct comparisons in the final graph question.

❌ Where students lost marks

• Mixing up preclinical and clinical testing.
• Giving vague control variables.
• Not mentioning ethics for the placebo question.
• Forgetting that the question asks for why doctors concluded, so evidence from the graph is needed.

🧠 Full-mark strategy

• For 1-mark items: be short and exact.
• For 2-mark compare questions: make two separate comparison points.
• Always read the graph given, even if you think you know the science already.