| I: | transports the atmospheric air to the alveoli |
| II: | clears inhaled air from foreign particles |
| III: | humidifies and also brings the air to body temperature |
| IV: | is the site of actual diffusion of O2 and CO2 between blood and atmospheric air |
| Assertion (A): | It is critical that the lungs are situated in the thoracic chamber which is anatomically an air-tight chamber. |
| Reason (R): | Changes in thoracic cavity volume generate pressure differences that lead to passive expansion and contraction of the lungs during breathing. |
| 1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
| 3. | (A) is True but (R) is False. |
| 4. | (A) is False but (R) is True. |
| I: | Gills are found in aquatic arthropods (e.g., crustaceans) and aquatic insect larvae but are absent in adult terrestrial arthropods. |
| II: | Terrestrial arthropods use a tracheal system, not gills, for gas exchange. |
| III: | Gills require a moist environment, which is absent in terrestrial habitats. |
| 1. | Gills are highly fragile and tend to collapse in air, drastically reducing their effective surface area for gas exchange. |
| 2. | Gills are incapable of detecting changes in atmospheric oxygen concentration. |
| 3. | Gills actively repel oxygen molecules in the absence of water. |
| 4. | Gills lack any blood vessels in their structure, making them inefficient for oxygen transport in air. |