Explain how uncontrolled mitosis can lead to cancer and describe one consequence of this for the body.

Edexcel GCSE Biology (1BI0) — 2.1 Mitosis and the cell cycle · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Cancer is a non-communicable disease that affects millions of people worldwide. It arises when changes occur in cells that affect the normal cell cycle.

Model answer (4 marks)

Uncontrolled mitosis occurs when the normal regulatory controls on the cell cycle are lost, allowing cells to divide continuously without the usual checkpoints. This loss of regulation means that cells keep proliferating, forming a mass of cells known as a tumour. The tumour can grow large enough to compress or invade surrounding tissues and organs, disrupting their normal function. In some cases the tumour may also spread to other parts of the body, further impairing health.

Examiner tips

  • Use the word 'uncontrolled' and mention loss of checkpoints; describe tumour formation; explain compression/invasion; optionally note metastasis.
  • Show clear link between cell‑cycle control loss and continuous division.
  • Use terms like 'mass of cells', 'compress', 'invade', 'metastasise'.
  • Keep answer concise – 4 marks only.

Mark scheme (4 marks)

  1. Cancer is caused by changes in the cell that lead to uncontrolled cell growth and division (mitosis)
  2. The cell cycle is no longer regulated / the normal controls on the cell cycle are lost
  3. A tumour (mass of cells) forms as a result of continued uncontrolled division
  4. The tumour can compress / invade surrounding tissues or organs, preventing them from functioning normally (accept: the tumour may spread to other parts of the body)

Key terms in this question

cancer · mitosis

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