CAIE IGCSE Biology 9.3.5 Capillary Adaptations for Exchange
Practise linking one-cell-thick walls, narrow lumens and extensive networks to efficient capillary exchange.
- Syllabus
- 2026–2028
- Course
- Biology 0610
Practise linking one-cell-thick walls, narrow lumens and extensive networks to efficient capillary exchange.
Fig. 3.1 is a diagram of alveoli and associated blood vessels.

Fig. 3.1
Explain how the structure of a capillary is related to its function.
any three from:
allows delivery of named useful substances (to tissues) / removal of named waste ;
thin (capillary) wall / wall is one cell thick ;
small lumen / AW ;
short diffusion distance / close contact ;
slows down blood flow (to maximise time for diffusion) ;
gaps between (capillary) cells ;
AVP ;