Describe the role of valves in the heart, and explain why the wall of the left ventricle is thicker than the wall of the right ventricle.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
Valves prevent the backflow of blood. For example, the tricuspid valve lies between the right atrium and the right ventricle. The left ventricle must pump blood at a higher pressure to reach the systemic circulation, so its wall is thicker, allowing it to contract more forcefully and generate greater pressure.
Examiner tips
- Use the word ‘prevent’ for the valve function; give a specific valve and its location; state the pressure difference; link wall thickness to forceful contraction.
- Keep each point brief and use exam‑specific terminology.
Mark scheme (4 marks)
- Valves prevent the backflow of blood (in the heart).
- Named example of a valve and its correct location between two named chambers or between a ventricle and an artery.
- The left ventricle must pump blood at higher pressure / over a greater distance than the right ventricle.
- A thicker muscular wall allows the left ventricle to contract more forcefully / generate greater pressure.
Key terms in this question
valves · left ventricle · right ventricle
Related
- All Cambridge International IGCSE Biology (0610) revision notes →
- How to answer a "Describe and Explain" question →
- Decode the mark scheme abbreviations →
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