AQA GCSE Combined Science: Trilogy Biology Paper 1 (Foundation), 2024: Question 2

✅ Correct answer

To act as a control, or to compare the other results to.

💡 Key knowledge

• A control gives a baseline result.
• It shows what happens with no wind.
• This helps show the effect of the fan/wind speed on mass loss.

🧠 Exam technique

For 1 mark, one clear idea is enough. The mark scheme accepts control or a comparison idea.

❌ Common errors

• Saying “control variable” — not the same thing.
• Giving a vague answer like “to make it fair” without saying what the fan-off result is for.

✅ Correct answer

The loss of mass increases as fan speed increases.

💡 Key knowledge

• Table 1 shows: off 0.06 g, low 0.15 g, medium 0.23 g, high 0.31 g.
• So stronger wind means more water is lost from the leaves.

🧠 Exam technique

Always quote the trend from the table. A simple statement like as fan speed increases, mass loss increases is enough for the mark.

❌ Common errors

• Saying the mass loss decreases.
• Describing the numbers without stating the trend.
• Forgetting that the question asks about loss of mass, not final mass.

✅ Correct answer

The leaves lost water because water evaporated from the leaf, through the stomata.

💡 Key knowledge

• This is transpiration.
• Water leaves the leaf as water vapour.
• The mass decreases because water has left the leaf.

🧠 Exam technique

This is a 3-mark explain question, so give a chain of reasoning:
loss of water → evaporation/transpiration → through stomata.

❌ Common errors

• Saying only “it got lighter” with no explanation.
• Not naming stomata.
• Confusing evaporation with photosynthesis.

Examiner note: top answers used the correct biology terms and linked them together. One-word answers usually did not secure all 3 marks.

✅ Correct answer

greater

💡 Key knowledge

A higher temperature increases evaporation, so more water is lost from the leaves.

🧠 Exam technique

This is a direct recall item. Choose the word that matches the biology: warmer conditions speed up water loss.

❌ Common errors

Choosing smaller or the same. Higher temperature does not reduce transpiration.

✅ Correct answer

Do the investigation again using the same method.

💡 Key knowledge

• Repeatability means getting similar results when the same person repeats the investigation using the same method.
• This checks whether the results are reliable.

🧠 Exam technique

Watch the key word repeatability. It means repeating with the same method, not changing the plant or the method.

❌ Common errors

• Using a different method — that does not test repeatability.
• Using a different type of plant — this changes the variable and makes results less comparable.

🧠 What top answers did

• Used the exact scientific word control for 2.1.
• Described the trend in the table clearly for 2.2.
• Gave a full chain of explanation for 2.3: water loss → evaporation/transpiration → stomata.
• Recognised that repeatability means repeating the investigation using the same method.

❌ Marks were often lost when students

• Used vague phrases like “fair test” without explaining the role of the control.
• Mixed up control and control variable.
• Forgot to mention stomata in the explanation of mass loss.
• Did not read the table carefully and got the trend wrong.