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Biology · Topic

Cells, microscopy and organisation

Magnification questions want a unit and a sensibly rounded figure.

3 original questions in the bank, worth 7 marks · above the two-per-topic floor

Drill this topic All cells, microscopy and organisation questions

The questions, with the examiner reasoning

Calculate2 marksBGCSE

A cell is 0.05 mm long. In a photograph it appears as 25 mm long. Calculate the magnification of the photograph.

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Answer: ×500

  1. Magnification = image size ÷ actual size
  2. = 25 ÷ 0.05
  3. = ×500

Examiner technique: Both lengths must be in the same unit before dividing — here they already are. Convert first, then divide, then write the × sign with no unit.

State1 markBoth boards

Which structure is present in a plant cell but not in an animal cell?

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Answer: Chloroplast

  1. Chloroplasts are the site of photosynthesis
  2. Animal cells do not photosynthesise
  3. So chloroplasts are plant-only
  • A. Chloroplast — Correct: chloroplasts carry out photosynthesis and are only found in photosynthesis-ing plant cells.
  • B. Ribosome — Ribosomes are in every living cell, plant or animal — protein synthesis happens everywhere.
  • C. Nucleus — Animal cells have nuclei too, apart from a few specialised exceptions.
  • D. Cell membrane — Every cell has a membrane; it is the cell wall that plants add outside it, not the membrane itself.

Examiner technique: Watch the wording: cell wall is plant-only, but cell membrane is not. Questions like this are testing whether you read the word.

Annotate / Label4 marksBoth boards

Figure 2 describes four features of a root hair cell: a long, thin extension of the cell surface; a large permanent vacuole filling much of the cell; no chloroplasts; and many mitochondria. Name each feature and state what it is for, in the form you would write on the lines beside a diagram.

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Answer: Root hair (extension) — increases surface area for water uptake. Large permanent vacuole — stores cell sap and keeps the cell rigid. No chloroplasts — the cell is underground, in darkness, so photosynthesis cannot occur. Many mitochondria — release energy for active transport of mineral ions.

  1. Names the root hair extension and gives its function: surface area for absorption (1 mark)
  2. Names the permanent vacuole and gives its function: stores sap, helps keep the cell firm (1 mark)
  3. States that chloroplasts are absent and links it to the absence of light underground (1 mark)
  4. Names the mitochondria and links the number to active transport and energy release (1 mark)

Examiner technique: Label questions are the cheapest marks on the paper and the most commonly rushed. Draw the line, name the part, then add its job in three or four words — the job is usually the mark you are actually being tested on.