Q149 / 180 · NEET 2013 (All India) · Zoology
The figure shows a diagrammatic view of human respiratory system with labels $A, B, C$ and $D$. Select the option, which gives correct identification and main function and/or characteristic.


- AA-trachea-long tube supported by complete cartilaginous rings for conducting inspired air
- BB-pleural membrane-surround ribs on both sides to provide cushion against rubbing
- Correct answerCC-alveoli-thin walled vascular bag-like structures for exchange of gases
- DD-lower end of lungs-diaphragm pulls it down during inspiration
Solution
C-Alveoli are thin-walled vascular bag-like structures for exchange of gases. A-trachea or wind pipe is an air conducting tube through, which transport of gases takes place. B-pleural membrane is double layered, which reduces friction on the lung surface. D-diaphragm is involved in the inspiration and expiration process of breathing.
Hence, the correct answer is option: 'C'.