# Explain why the blood leaving the left ventricle must be maintained at a higher pressure than the blood leaving the right ventricle.

> OCR A-Level Biology A (H420) — 3.2 Transport in animals · Explain · 4 marks

> The heart pumps blood into two separate circulatory loops simultaneously. The left and right ventricles contract at the same time, yet the pressure they generate differs significantly.

## Mark scheme (4 marks)

1. The left ventricle pumps blood to the body (systemic circulation), which is a much greater distance than the pulmonary circulation
2. Greater pressure is needed to overcome the higher resistance of the longer systemic circuit
3. The right ventricle only needs to pump blood to the lungs (pulmonary circulation), which are close to the heart
4. High pressure in the pulmonary circulation would damage the delicate capillaries of the alveoli, impairing gas exchange

## Key terms

- [left ventricle](https://www.gradenine.co.uk/glossary/left-ventricle)
- [right ventricle](https://www.gradenine.co.uk/glossary/right-ventricle)

## Related

- [Revision notes for OCR A-Level Biology A (H420)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-the-blood-leaving-the-20345092) · Published by Druglandscape Ltd.