Answers

2016-06-16T22:17:04+08:00
The trunk of the tree serves as the trachea which connects the mouth and nose to the lungs. The branches represents the bronchi, then the twig represents the bronchioles and the leaves represents the alveoli.
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2016-06-17T10:02:30+08:00
I think it represents as a tube in which the air passes in breathing system

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