Explain how smoking cigarettes can increase the risk of developing lung cancer.

Edexcel GCSE Biology (1BI0) — 5.3 Non-communicable diseases · Explain · 4 marks · View as Markdown

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

Lung cancer is one of the most common cancers in the United Kingdom. Research consistently shows that cigarette smokers are significantly more likely to develop lung cancer than non-smokers.

Model answer (4 marks)

Cigarette smoke contains carcinogens such as tar and polycyclic aromatic hydrocarbons.
These chemicals enter the lungs and damage the DNA of lung cells.
The DNA damage leads to mutations that disrupt normal cell‑cycle control.
Mutated cells divide uncontrollably, forming a tumour that can develop into lung cancer.

Examiner tips

  • Use the exact terms: carcinogens, DNA mutations, uncontrolled cell division, tumour.
  • Show the causal chain in order.
  • Keep each point brief but complete.
  • Mention the specific chemicals if possible.

Common mistakes

  • Confusing ‘carcinogens’ with ‘tobacco smoke’ as a whole.
  • Failing to link DNA mutations to uncontrolled cell growth.
  • Using vague language such as ‘bad chemicals’ instead of ‘carcinogens’.

Mark scheme (4 marks)

  1. Cigarette smoke contains carcinogens (cancer-causing chemicals / tar)
  2. Carcinogens cause mutations in the DNA of lung cells
  3. Mutations cause uncontrolled cell division / growth
  4. This results in the formation of a tumour / cancer

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