Explain how drinking excessive amounts of alcohol can lead to cirrhosis of the liver.

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).

Alcohol is broken down in the liver. Long-term excessive alcohol consumption is a known risk factor for serious liver disease. Cirrhosis is a non-communicable disease that affects millions of people worldwide.

Model answer (4 marks)

Alcohol is metabolised in the liver by alcohol dehydrogenase, producing acetaldehyde.
Acetaldehyde is a toxic by‑product that damages hepatocytes.
The damage leads to cell death and inflammation of liver tissue.
The liver replaces the damaged tissue with scar (fibrotic) tissue, producing cirrhosis.

Examiner tips

Use the exact sequence: metabolism → toxic by‑product → cell damage → scar tissue. Show the key enzyme (alcohol dehydrogenase) and the toxic product (acetaldehyde).
Keep the answer concise – one sentence per point – to match the 4‑mark structure.

Common mistakes

Confusing the liver with the stomach as the site of alcohol breakdown. Mentioning alcohol as the direct cause of scar tissue without the intermediate toxic by‑product.

Mark scheme (4 marks)

Alcohol is broken down / metabolised in the liver
The breakdown of alcohol produces toxic products / toxic by-products
These toxic products damage / destroy liver cells / liver tissue
Damaged liver tissue is replaced by scar tissue, causing cirrhosis

Key terms in this question

cirrhosis · liver