Question

Regarding assertion and reason, choose the correct option.

Assertion [A]: The affinity of hemoglobin for oxygen is dependent on the partial pressure of oxygen.

Reason [R]: Hemoglobin has a low affinity for oxygen.

• A. Assertion [A] is True and Reason [R] is False.
• B. Reason [R] is True and Assertion [A] is False
• C. Assertion [A] is True and Reason [R] is True and is a correct explanation to [A].
• D. Assertion [A] is True and Reason [R] is True but is not a correct explanation to [A].

Answer 1

The correct option is C

Assertion [A] is True and Reason [R] is True and is a correct explanation to [A].

Hemoglobin molecules have four subunits that can hold four oxygen molecules. When the first subunit binds an oxygen molecule, its configuration changes, and increases the affinity of the second subunit to oxygen. This increase in affinityincreases with each subunit that binds to oxygen. The fourth subunit will then have the highest affinity for oxygen. The affinity of hemoglobin for oxygen is dependent on the partial pressure of oxygen it is exposed to. This can be depicted in a graph with x-axis representing partial pressure of oxygen and the y-axis representing oxygen saturation. This is called the Oxygen Dissociation Curve.