AQA GCSE Combined Science: Trilogy Physics Paper 1 (Higher), 2020: Question 4

✅ Correct answer

A renewable biofuel

💡 Key knowledge

• Renewable means it can be replaced naturally in a short time.
• Biofuel means it comes from plant material or other biological material.
• Wood is a fuel from trees, so it is a biofuel.

🧠 Exam technique

• Read the word wood and connect it to plant material.
• If you know it is from living material, the safest answer is renewable biofuel.

❌ Common errors

• Choosing non-renewable fossil fuel because it is burned.
• Thinking all fuels are fossil fuels.
• Mixing up renewable and non-renewable.

✅ Correct answers

Any two of the following:

• Burning wood causes air pollution / creates smoke.
• Burning wood may lead to deforestation.
• Destruction of habitats.
• Burning wood is carbon-neutral.

💡 Key knowledge

• Air pollution means harmful substances enter the air.
• Deforestation means trees are cut down on a large scale.
• Habitat destruction means animals and plants lose their homes.
• Carbon-neutral means the CO₂ released when burned is balanced by CO₂ absorbed while the trees grew.

🧠 Exam technique

• Write two separate effects clearly; do not repeat the same idea in different words.
• Best answers are short and direct, such as burning wood causes air pollution .

❌ Common errors

• Writing cutting down trees alone — the mark scheme says ignore this unless linked to deforestation.
• Vague answers like “it is bad for the environment” do not gain marks.
• Giving only one valid point and one repeated point.

✅ Correct answers

• Wood: the chemical store of energy decreases.
• Pipe: the internal/thermal store of energy increases.
• Water: the internal/thermal store of energy increases.

💡 Key knowledge

• The wood is burning, so its chemical energy store gets smaller.
• The pipe and water are warmed up, so their internal (thermal) energy stores increase.
• Use the word store if possible — this is the GCSE energy model.

🧠 Exam technique

• For full marks, mention both the object and what happens to the store.
• Example: the internal store of the pipe increases .
• Do not just say “it gets hotter” for the pipe and water — that is less precise.

❌ Common errors

• Saying the wood’s thermal store increases — the wood is the fuel being used up.
• Forgetting one of the three objects.
• Using heat energy instead of store language.

✅ Correct answer

• Energy is dissipated to the surroundings.
• Energy is lost at the same rate as it is transferred to the water.

💡 Key knowledge

• If the water is being heated but its temperature stays the same, the energy coming in is balanced by energy leaving.
• This is a balanced energy transfer.
• Temperature only increases if the water gains energy overall.

🧠 Exam technique

• Use the phrase same rate — this is exactly what earns the second mark.
• A strong answer: Energy is dissipated to the surroundings at the same rate as it is transferred to the water.

❌ Common errors

• Saying “the fire is not hot enough” — not what the mark scheme wants.
• Thinking constant temperature means no energy transfer is happening.
• Forgetting that energy can be lost to the surroundings.

📐 Calculations / step-by-step

This question does not require calculations, but the same exam habit helps:

1. Read the command word carefully.
2. Give the exact number of points asked for.
3. Use the correct scientific term.
4. Keep answers short and specific.

🧠 What distinguished top-level responses

• They used precise energy-store vocabulary.
• They gave two different environmental effects in part (b).
• They linked constant temperature to energy in = energy out.

❌ Biggest traps in this question

• Mixing up renewable and non-renewable.
• Not being specific enough about environmental effects.
• Talking about “heat” instead of energy stores.
• Forgetting the “same rate” idea in part (d).