A-LevelBiologyGas exchange9700/12 · May/June 2017 · Q331 Mark
Some of the requirements of an efficient gas exchange system are a large surface area and a short diffusion distance. What is correct about how alveoli are adapted to meet these requirements? [Table with columns 'large surface area', 'short diffusion distance' and rows A, B, C, D]
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Alarge surface area collagen and elastin fibres that allow the alveoli to stretch, short diffusion distance an extracellular layer round the alveolus wall contains blood capillaries
Blarge surface area gases dissolve in a layer of liquid to speed up diffusion, short diffusion distance walls of alveoli are squamous epithelium
Clarge surface area many folded interconnected alveoli, short diffusion distance capillaries are next to alveolus wall
Dlarge surface area sac shape of alveoli formed by squamous cells, short diffusion distance red blood cells are very close to capillary walls
✓ Correct answer
C: large surface area many folded interconnected alveoli, short diffusion distance capillaries are next to alveolus wall
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