IB Biology HL 3.2.1 Capillary Adaptations Question Bank
Practise IB Biology HL 3.2.1 by explaining how one-cell, permeable capillary walls and narrow lumens support exchange with tissues.
- Syllabus
- First assessment 2025
- Course
- Biology HL
- Level
- HL
Exam points
- Explain capillary exchange using one-cell walls, narrow lumens and permeable gaps.
- Link capillary density and exchange surface to oxygen or solute delivery in tissues.
B3.2.1—Capillary adaptations question 1
[Maximum number: 3]
Explain how the structure of capillaries relates to their functions.
Complete correct answer:
Adaptations of capillaries for exchange include: capillary walls are thin/one cell thick for better diffusion; the lumen has a small diameter/narrow lumen so capillaries can fit into small spaces/between cells; the small diameter gives greater surface area for molecular exchange; pores between cells of the walls allow plasma to leak out; pores between cells of the walls allow phagocytes/immune components to enter tissues; only one red blood cell passes at a time for efficient oxygen uptake.
Marking guidance:
Award up to 3 marks. Do not accept membranes for the thin wall point.
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