Question

Assertion (A): Blood takes up oxygen from the alveolar air and release CO₂ during exchange.

Reason (R): The concentration of O₂ is more in alveolar air.

Options

• Both A and R are true and R is the correct explanation of A.

• Both A and R are true but R is not the correct explanation of A.

• A is true but R is false.

• A is false but R is true.

Answer 1

Both A and R are true and R is the correct explanation of A.

Explanation:

The assertion is true because gas exchange happens at the respiratory surface of the lungs, where deoxygenated blood absorbs oxygen and dumps carbon dioxide into the alveoli. The reason is also true and serves as the correct explanation because gas exchange relies entirely on simple diffusion along a concentration gradient. Since the concentration (and partial pressure) of oxygen is significantly higher in the alveolar air than in the incoming blood, oxygen naturally flows across the membrane and into the blood vessels.