27 marks of exam-style questions on GCSE cell biology. Try each question first, then open the mark scheme to check your answer. Download the PDF for a printable version with answer lines and graph paper.
Question 1: Plant cells
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A: nucleus. B: cell wall. C: (permanent) vacuole.
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It absorbs light for photosynthesis. Allow "where photosynthesis happens".
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Plasmid.
Question 2: Microscopy
A student uses a light microscope to look at cells from the inside of their cheek.
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Ribosomes are too small to see, because the resolution of a light microscope is too low.
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6 ÷ 400 (1 mark) = 0.015 mm (1 mark) = 15 µm (1 mark). A correct answer of 15 µm with no working gets all 3 marks.
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Higher resolution or higher magnification, so it shows more detail.
Question 3: Cell division
The diagrams show four stages of the cell cycle. They are not in the correct order.
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X, Z, W, Y.
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Any two from: the cell grows; the DNA is copied (replicated); more organelles are made, such as ribosomes or mitochondria.
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Growth, repair, or asexual reproduction.
Question 4: Osmosis practical
A student put potato cylinders into salt solutions of different concentrations for 24 hours.
| Concentration in mol/dm³ | Mass at start in g | Mass at end in g | Change in mass in % |
|---|---|---|---|
| 0.0 | 2.40 | 2.69 | +12.1 |
| 0.2 | 2.52 | 2.61 | +3.6 |
| 0.4 | 2.50 | 2.35 | X |
| 0.6 | 2.46 | 2.18 | −11.4 |
| 0.8 | 2.55 | 2.12 | −16.9 |
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(2.35 − 2.50) ÷ 2.50 × 100 (1 mark) = −6.0 % (1 mark). The minus sign is needed for the second mark.
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All points plotted correctly (2 marks; 1 mark for three or four correct), and a smooth line of best fit (1 mark).
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About 0.27 mol/dm³, where the line crosses 0 %: there is no net movement of water at this concentration. Accept 0.25 to 0.30.
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To remove excess solution, so only the mass of the potato is measured.
Question 5: Transport
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Level 3 (5 to 6 marks): a detailed comparison of all three processes, covering what moves, the direction of movement and whether energy is needed. Level 2 (3 to 4 marks): some comparison of at least two processes. Level 1 (1 to 2 marks): simple statements with little comparison.
Indicative content:
- Diffusion and osmosis are passive and do not need energy; active transport needs energy from respiration.
- Diffusion is the net movement of particles from high to low concentration.
- Osmosis is the movement of water only, from a dilute to a more concentrated solution, through a partially permeable membrane.
- Active transport moves substances against a concentration gradient, from low to high concentration.
- Examples: oxygen diffusing into cells; mineral ions entering root hair cells by active transport.
