# Plasma is the liquid component of blood. Explain how plasma is adapted to transport substances around the human body, and describe the role of platelets in protecting the body when a blood vessel is damaged.

> WJEC A-Level Biology (Wales) — 2.3 Adaptations for transport in plants and animals · Explain · 5 marks

> Blood is made up of four main components: plasma, red blood cells, white blood cells and platelets. Each component has a specific role in maintaining health.

## Mark scheme (5 marks)

1. Plasma is a liquid / pale yellow liquid that carries substances in solution
2. Plasma transports named substances such as nutrients, hormones, urea OR antibodies
3. Platelets stick to the broken / damaged vessel wall (when a blood vessel is damaged)
4. Platelets block the cut / form a clot / scab, preventing further blood loss
5. This prevents pathogens from entering the blood vessel / allows the vessel to heal

## Key terms

- [plasma](https://www.gradenine.co.uk/glossary/plasma)
- [platelets](https://www.gradenine.co.uk/glossary/platelets)

## Related

- [Revision notes for WJEC A-Level Biology (Wales)](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/plasma-is-the-liquid-component-of-5a988e7c) · Published by Druglandscape Ltd.