Describe the path taken by a red blood cell through the heart, starting from when it arrives in the right atrium and ending when it leaves through the aorta. Name the blood vessels and valves it passes through.

Cambridge International IGCSE Biology (0610) — 9.2 Heart · Describe · 4 marks · View as Markdown

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

Model answer (4 marks)

Blood enters the right atrium, passes through the tricuspid valve into the right ventricle. The right ventricle contracts, ejecting blood through the pulmonary semilunar valve into the pulmonary artery to the lungs. Oxygenated blood returns via the pulmonary vein into the left atrium, passes through the bicuspid (mitral) valve into the left ventricle. The left ventricle contracts, ejecting blood through the aortic semilunar valve into the aorta.

Examiner tips

  • Use the correct valve names (tricuspid, bicuspid, semilunar) and vessel names (pulmonary artery/vein, aorta).
  • Show the sequence clearly: atrium → valve → ventricle → valve → vessel → next chamber.
  • Include the direction of flow (e.g., ‘into’ or ‘through’).

Common mistakes

  • Mixing up valve names (e.g., calling the aortic valve tricuspid).
  • Omitting the pulmonary artery or pulmonary vein.

Mark scheme (4 marks)

  1. Blood moves from the right atrium through the tricuspid valve into the right ventricle
  2. Blood leaves the right ventricle through the semilunar valve and travels to the lungs via the pulmonary artery
  3. Oxygenated blood returns from the lungs via the pulmonary vein and enters the left atrium, then passes through the bicuspid valve into the left ventricle
  4. The left ventricle contracts and blood exits through the semilunar valve into the aorta

Key terms in this question

aorta

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