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biology 0610printed 147 · PDF 147
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Aitchison College Academic Resources. — The giagram shows a section through an alveolus and a capillary.
Why does carbon dioxide move from X to Y?
Air has a lower concentration of carbon dioxide than blood.
Carbon dioxide moves more freely in air than in blood.
a
Carbon dioxide must replace oxygen.
=]
Diffusion of carbon dioxide can only be out of the blood.
4.
The diagram shows some structures in the human neck and thorax.
The lining of tube Q has cilia.
What is an important function of the cilia?
A to help in the exchange of gases
B to increase the internal surface area of tube Q
C to moisten the air entering and leaving the lungs
D to move mucus towards the throat
5.
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