AQA GCSE Biology Biology Paper 1 (Higher), 2024: Question 8

✅ Correct answer

Any one of:

• the cell grows
• there is an increase in the number of sub-cellular structures
• there is an increase in the number of mitochondria
• there is an increase in the number of ribosomes

💡 Key knowledge

• Before mitosis, the cell prepares by making more cell components.
• Growth means the cell gets bigger before division.
• More mitochondria can help provide energy for cell activities.
• More ribosomes help with protein synthesis.

🧠 Exam technique

• Only one valid point is needed for 1 mark.
• Use a clear biological change, not something vague like “it gets ready”.
• If you write more than one point, make sure at least one is correct.

❌ Common errors

• Writing “the nucleus grows” — this is not accepted.
• Writing changes that happen during division, not before it.
• Using vague phrases like “the cell changes” with no detail.

✅ Correct answer

Cell membrane

💡 Key knowledge

• The cell membrane is the thin outer boundary around the cell.
• In a diagram of a cell in mitosis, this is usually shown as the outer circular outline.

🧠 Exam technique

• Use the exact biological name.
• “Membrane” or “cell membrane” is accepted.

❌ Common errors

• Calling it the cell wall — animal cells do not have a cell wall.
• Calling it the nucleus — the label points to the outside boundary.

📐 Calculations: step-by-step

1. Use the cylinder formula:
   length = volume ÷ (π × radius²)
2. Substitute the values:
   length = 24 500 000 ÷ (3.14 × 125²)
3. Calculate the denominator:
   125² = 15 625
   3.14 × 15 625 = 49 062.5
4. Find the real length:
   24 500 000 ÷ 49 062.5 = 499.36 nm
   So the real length is about 499 nm.
5. Convert the image size to the same unit:
   4 mm = 4 000 000 nm
6. Use magnification:
   magnification = image size ÷ real size
   magnification = 4 000 000 ÷ 499.36 ≈ 8010

Final answer: ×8010

💡 Key knowledge

• Always use the correct formula for the shape given.
• Magnification = image size ÷ real size.
• Units must match before dividing.
• For this question, nm and mm must be converted to the same unit.

🧠 Exam technique

• Write down each substitution step to gain method marks.
• Use a calculator carefully and keep enough digits until the end.
• Round sensibly only at the final step.
• Include the final magnification as a number only, or with × if shown.

❌ Common errors and traps

• Forgetting to square the radius.
• Using 4 mm without converting it to nm.
• Using the wrong magnification formula.
• Giving the answer with no working, which can lose method marks.
• Rounding too early and getting a slightly different final value.

✅ Correct answer

• Chromosomes cannot be pulled by the fibres to each end of the cell.
• So the nucleus cannot divide.

💡 Key knowledge

• During mitosis, fibres attach to chromosomes and pull them apart.
• This ensures each new cell gets a set of chromosomes.
• If the chromosomes cannot move to opposite ends, mitosis cannot finish properly.

🧠 Exam technique

• For 2 marks, make two linked points.
• Say what cannot happen, then explain the consequence.
• Use precise mitosis language: chromosomes, fibres, nucleus.

❌ Common errors

• Writing that chromosomes “cannot be separated” without linking to fibres.
• Talking only about the whole cell dividing, instead of the nucleus.
• Writing “the cell dies” without explaining why.

✅ Correct answer

The tumour cannot grow, proliferate, or spread.

💡 Key knowledge

• Cancer involves uncontrolled cell division.
• If cells cannot divide, the tumour cannot increase in size.
• This can also prevent secondary tumours from forming.

🧠 Exam technique

• One clear reason is enough.
• Use “tumour” or “secondary tumours” for strong exam wording.

❌ Common errors

• Saying only “it stops uncontrolled cell division” — this was ignored in the mark scheme.
• Saying “the cancer cannot become malignant” — not accepted here.
• Giving a vague answer with no reference to tumour growth or spread.

✅ Correct answer

Testing the drugs on live tissues in a laboratory

💡 Key knowledge

• Preclinical testing happens before clinical trials.
• It may involve testing on cells or tissues in the lab.
• This helps check whether the drug works and whether it causes harmful effects.

🧠 Exam technique

• Read the options carefully: only one matches the mark scheme.
• “Live tissues in a laboratory” is the best answer here.

❌ Common errors

• Choosing “testing with chemicals in a laboratory” — too vague and not the answer.
• Choosing “testing the drugs on live tissues in a laboratory” is correct.
• Confusing preclinical testing with clinical trials on people.

📌 High-value facts

• Before division, cells grow and make more sub-cellular structures.
• The cell membrane is the outer boundary of an animal cell.
• Magnification = image size ÷ real size.
• Units must always be the same before calculating magnification.
• Mitosis depends on fibres attaching to chromosomes.
• Stopping cell division stops tumour growth and spread.
• Preclinical testing uses live tissues in a laboratory.

🧠 How to gain marks fast

• Use precise biology terms.
• In calculations, show working clearly.
• When asked to explain, link cause → effect.
• If a question asks for one mark, one valid fact is enough.