# Red blood cells are specialised cells that carry oxygen around the body. Explain how the structure of red blood cells is adapted to carry out this function efficiently.

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

## Mark scheme (5 marks)

1. Red blood cells have a biconcave shape
2. The biconcave shape increases the surface area for gaseous exchange / oxygen uptake
3. Red blood cells contain haemoglobin which binds to / carries oxygen
4. Red blood cells have no nucleus
5. Having no nucleus leaves more space / room for haemoglobin, so more oxygen can be carried

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