Which of the following has the highest affinity for oxygen?
1. HbS
2. HbA
3. HbF
4. Methemoglobin

Assertion: Chloride concentration is higher in systemic venous blood than in systemic arterial blood.
Reason: The rise in intracellular bicarbonate in RBCs leads to bicarbonate intake and chloride export.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

The diagram below shows:

1. The Bohr effect
2. The chloride shift
3. The Haldane effect
4. Hering-Breuer reflex

A large proportion of oxygen is left unsused in the human blood even after its uptake by the body tissues. This ${\mathrm{O}}_2$
1. raises the ${\mathrm{P}}_{{\mathrm{CO}}_2}$ of blood to 75 mm of Hg
2. is enough to keep oxyhaemoglobin
3. helps in releasing more ${\mathrm{O}}_2$ to the epithelial tissues
4. acts as a reserve during muscular exercise

Assertion: A person who is born and lives at sea level will develop a slightly smaller lung capacity than a person who spends their life at a high altitude.
Reason: The partial pressure of oxygen is lower at higher altitude which, as a result means that oxygen less readily diffuses into the bloodstream.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.