Explain the role of valves in the heart and why they are important for the efficient circulation of blood.

WJEC GCSE Biology (Wales) — 1.4.2 The heart · Explain · 4 marks · View as Markdown

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

Model answer (4 marks)

Valves prevent the backflow of blood, ensuring it moves in one direction.
They open when the pressure behind them is greater than the pressure in front, and close when the pressure in front is greater.
The atrioventricular (bicuspid and tricuspid) valves lie between the atria and ventricles.
The semilunar valves sit at the exits of the ventricles (aorta and pulmonary artery) and stop blood returning to the ventricles.

Examiner tips

  • Use the phrase "prevent backflow" to hit the key point. Show the pressure‑difference mechanism. Name both valve types and their locations. Explain the functional consequence for efficient circulation.

Common mistakes

  • Forgetting to mention the atrioventricular valves. Confusing the positions of the semilunar valves. Using vague terms like "keep blood moving" without explaining the pressure principle.

Mark scheme (4 marks)

  1. Valves prevent the backflow of blood
  2. Valves open when pressure behind them is greater, and close when pressure in front is greater
  3. Atrioventricular (bicuspid/tricuspid) valves are located between the atria and ventricles
  4. Semilunar valves are located at the exits of the ventricles (in the aorta and pulmonary artery) to prevent blood returning to the ventricles

Key terms in this question

valves

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