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named review panel.
Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.
Key point
Know the specific effects of alcohol and tobacco substances. Explain antibiotic resistance as natural selection of resistant bacteria. Understand why antibiotics should not be overused.
Topic 15 is relatively small but carries consistent marks. Key areas: the effects of alcohol on the liver and behaviour, the harmful substances in tobacco smoke, and antibiotic resistance. This topic often appears as a 4–6 mark explain or discuss question.
Priority 1: Effects of alcohol
Alcohol is a depressant: it slows down reactions, impairs judgement and coordination, and affects speech. Long-term effects: liver damage (cirrhosis), weight gain, addiction (dependency). The liver breaks down alcohol, and excessive consumption damages liver cells.
Priority 2: Harmful substances in tobacco
Tar (carcinogen → cancer, damages cilia → bronchitis), nicotine (addictive, raises heart rate and blood pressure), carbon monoxide (reduces O₂ carrying capacity of blood), and particulates. Link each substance to its specific health effect.
Priority 3: Antibiotic resistance
Random mutation produces a bacterium resistant to an antibiotic. When the antibiotic is used, non-resistant bacteria die, but the resistant one survives and reproduces (natural selection). The resistant strain becomes common. This is why antibiotics should not be overused or taken for viral infections.
Frequently asked questions
Is this topic high-mark?
Usually 3–6 marks per paper. The marks are predictable: learn the specific health effects and antibiotic resistance mechanism.
Put the guide into practice
Questions and practical resources
Use a fresh question to check whether the idea can be applied without prompts.