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

✅ Correct answers

• A = cell membrane
• B = nucleus
• C = cytoplasm

💡 Key knowledge

• The cell membrane controls what enters and leaves the cell.
• The nucleus contains the genetic material and controls the cell.
• The cytoplasm is where most chemical reactions happen.
• Animal cells do not have a cell wall or chloroplasts.

🧠 Exam technique

• Use the word bank carefully: only pick structures found in an animal cell.
• Marks are separate, so each label can score independently.
• If the line points to the edge, it is usually the cell membrane.

❌ Common errors

• Writing cell wall or chloroplast for an animal cell.
• Mixing up nucleus and cytoplasm.
• Using vague answers like “outer part” instead of the exact name.

✅ Correct answer

To control the activities of the whole cell

💡 Key knowledge

The nucleus contains DNA, which carries the instructions for what the cell does.

🧠 Exam technique

In a multiple-choice/tick question, only one option is correct. Choose the answer that matches the standard GCSE definition.

❌ Common errors

• Choosing the cell sap answer — this is for plant vacuoles, not the nucleus.
• Choosing movement of substances — that is the cell membrane.

✅ Correct answer

To release energy in respiration

💡 Key knowledge

Mitochondria are the site of aerobic respiration, where energy is released for cell processes.

🧠 Exam technique

Watch out for answers about photosynthesis or protein production — those belong to other cell structures.

❌ Common errors

• Produce glucose during photosynthesis — this is a chloroplast function.
• Produce proteins — this is mainly ribosomes.

✅ Correct answers in order

1. Place the slide on the stage.
2. Look through the eyepiece lens.
3. Direct the light by moving the mirror.
4. Make the image larger by using the high power objective lens.

💡 Key knowledge

• The stage holds the slide.
• The eyepiece lens is where you look through.
• The mirror reflects light up through the specimen.
• The objective lens changes magnification.

🧠 Exam technique

• The mark scheme says the answers must be in this order.
• Use the exact label names from the diagram.
• If the question says “use labels from Figure 2”, copy the diagram wording precisely.

❌ Common errors

• Writing lens without saying eyepiece lens or objective lens.
• Putting the slide on the base instead of the stage.
• Mixing up mirror and lens roles.

📐 Calculations: step-by-step

1. Measure the image width from Y to Z.
2. The mark scheme allows 36 mm (also accept 35 to 37 mm).
3. Convert mm to µm: 36 mm × 1000 = 36,000 µm.
4. Use the equation:
   magnification = width of image ÷ real width of cell
5. Substitute the values:
   magnification = 36,000 ÷ 40
6. Calculate:
   magnification = 900

✅ Correct answer

Magnification = ×900

Note: the mark scheme says do not accept units with the final answer.

🧠 Exam technique

• Show each stage clearly: measurement, conversion, substitution, final answer.
• Always convert to the same unit before dividing.
• Use the equation exactly as given in the question.
• If your measurement is slightly different but sensible, it can still score if the method is correct.

❌ Common errors

• Forgetting to convert mm to µm.
• Dividing the wrong way round.
• Using 40 mm instead of 40 µm for the real width.
• Writing the final answer with units, when the mark scheme says not to.

💡 Key facts to memorise

• Animal cell parts: cell membrane, cytoplasm, nucleus.
• Nucleus: controls activities of the whole cell.
• Mitochondria: release energy in respiration.
• Microscope order: stage → eyepiece lens → mirror → objective lens.
• Magnification = image size ÷ real size.

🧠 How to secure the marks

• Learn exact definitions.
• Use the diagram labels carefully.
• Show conversion from mm to µm in calculations.
• Keep answers short, precise, and matched to the mark scheme wording.