# Explain how the components of blood enable it to carry out its transport functions in the body.

> Edexcel A-Level Biology A: Salters-Nuffield (9BN0) — 8 Grey Matter · Explain · 5 marks

> Blood is a tissue that transports many different substances around the body. It contains red blood cells, white blood cells, platelets and plasma.

## Mark scheme (5 marks)

1. Erythrocytes (red blood cells) contain haemoglobin
2. Haemoglobin binds to / carries oxygen, allowing transport of oxygen to tissues
3. Erythrocytes are biconcave / anucleate, giving a large surface area for oxygen uptake / more space for haemoglobin
4. Plasma transports dissolved substances such as nutrients, hormones, urea or carbon dioxide / dissolved gases around the body
5. Platelets are involved in blood clotting, preventing blood loss / entry of pathogens

## Related

- [Revision notes for Edexcel A-Level Biology A: Salters-Nuffield (9BN0)](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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