AIIMS 2018 Zoology Gas Exchange Assertion Reason Question
Assertion: easily diffuses from alveoli to tissues and from tissue to alveoli.
Reason: Alveoli is 2-celled thick and capillaries are thin walled
Both A and R are true and R is the correct explanation of A.
Both A and R are true but R is not correct explanation of A
A is true but R is false
A and R are false
Correct Answer
Detailed Explanation
O₂ diffuses from alveoli to tissues due to a concentration gradient, where the partial pressure of O₂ is higher in the alveoli compared to the tissues, facilitating its movement. Conversely, CO₂ diffuses from tissues to alveoli as its partial pressure is higher in the tissues, allowing for efficient gas exchange. The statement that "alveoli is not²⁻celled" is misleading; alveoli are indeed composed of a single layer of epithelial cells, which is crucial for the diffusion process, making the assertion about the alveoli being "not²⁻celled" incorrect. Thus, only the assertion regarding the diffusion of gases is accurate, validating option C.
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