A patient is diagnosed with cancer after a routine screening. Explain how cancer develops in the body and describe two consequences of uncontrolled cell division.

WJEC A-Level Biology (Wales) — 1.6 Cell division · Explain · 5 marks · View as Markdown

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

Cancer affects millions of people worldwide. It arises when normal cell division goes wrong.

Model answer (5 marks)

Cancer is caused by a mutation in the cell's DNA. The mutation leads to uncontrolled growth and division of cells, producing a large number of unwanted cells called a tumour. The first consequence is that the tumour can invade and damage surrounding tissues or organs. The second consequence is that normal cell functions are disrupted because abnormal cells take resources or crowd out healthy cells.

Examiner tips

  • Use the exact terminology: mutation, uncontrolled growth, tumour, invade, damage, disrupt normal function.
  • Show the causal chain: mutation → uncontrolled division → tumour → consequences.
  • Keep the answer concise and to the point to fit the 5 marks.

Common mistakes

  • Using vague terms like "cancer cells" instead of "mutation in DNA".
  • Failing to mention both consequences or mixing them up.
  • Writing too many words or irrelevant details that take away from the key points.

Mark scheme (5 marks)

  1. Cancer is caused by a mutation in the cell's DNA
  2. The mutation leads to uncontrolled growth and division of cells
  3. This produces a large number of unwanted cells called a tumour
  4. First consequence: the tumour can invade and damage surrounding tissues / organs
  5. Second consequence: normal cell functions are disrupted because abnormal cells take resources / crowd out healthy cells

Key terms in this question

cancer · cell division

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