Describe the route taken by a red blood cell as it travels from the vena cava to the aorta, naming the chambers and valves it passes through in the correct order.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
Blood enters the right atrium from the vena cava and passes through the tricuspid valve into the right ventricle.
Blood leaves the right ventricle through the pulmonary semilunar valve into the pulmonary artery and travels to the lungs.
Oxygenated blood returns from the lungs via the pulmonary vein into the left atrium and passes through the bicuspid (mitral) valve into the left ventricle.
Blood leaves the left ventricle through the aortic semilunar valve into the aorta; the left ventricle wall is thicker than the right because it must pump blood at higher pressure around the whole body.
Blood leaves the right ventricle through the pulmonary semilunar valve into the pulmonary artery and travels to the lungs.
Oxygenated blood returns from the lungs via the pulmonary vein into the left atrium and passes through the bicuspid (mitral) valve into the left ventricle.
Blood leaves the left ventricle through the aortic semilunar valve into the aorta; the left ventricle wall is thicker than the right because it must pump blood at higher pressure around the whole body.
Examiner tips
- Use the correct valve names (tricuspid, bicuspid, semilunar) and chamber order. Show the flow from vena cava to aorta in a clear, step‑by‑step sequence. Include the note on left ventricle wall thickness to earn the extra point.
Common mistakes
- Mixing up the valve names (e.g., calling the aortic valve tricuspid). Omitting the pulmonary artery step or the return via pulmonary vein. Using the wrong order of chambers (e.g., left atrium before right atrium).
Mark scheme (4 marks)
- Blood enters the right atrium from the vena cava and passes through the tricuspid valve into the right ventricle.
- Blood leaves the right ventricle through the semilunar valve into the pulmonary artery and travels to the lungs.
- Oxygenated blood returns from the lungs via the pulmonary vein into the left atrium and passes through the bicuspid valve into the left ventricle.
- Blood leaves the left ventricle through the semilunar valve into the aorta; the left ventricle wall is thicker than the right as it must pump blood at higher pressure around the whole body.
Key terms in this question
Related
- All Cambridge International IGCSE Biology (0610) revision notes →
- How to answer a "Describe" question →
- Decode the mark scheme abbreviations →
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