Describe the structure of alveoli and how this structure enables efficient gas exchange. (3 marks)
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Sample Answer
- Alveoli are tiny air sacs located at the end of bronchioles in the lungs.
- They have extremely thin walls (one cell thick) that enable gases to diffuse easily.
- They are surrounded by an extensive network of capillaries, which creates a large surface area for gas exchange.
- The close proximity between alveoli and capillaries results in a short diffusion distance for gases, allowing rapid oxygen and carbon dioxide exchange.
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Sample Answer
- Alveoli are tiny air sacs located at the end of bronchioles in the lungs.
- They have extremely thin walls (one cell thick) that enable gases to diffuse easily.
- They are surrounded by an extensive network of capillaries, which creates a large surface area for gas exchange.
- The close proximity between alveoli and capillaries results in a short diffusion distance for gases, allowing rapid oxygen and carbon dioxide exchange.