Question

Assertion :$C{O}_2$ is carried mainly in the form of bicarbonate ions very quickly formed within 2 sec. Reason: Carbonic anhydrase in the most quickly acting enzyme richly present in RBC.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

Blood is the medium of transport for oxygen and carbon dioxide. Nearly 20-25 per cent of carbon dioxide is transported by RBCs, whereas 70 per cent of it is carried as bicarbonate. About 7 per cent of carbon dioxide is carried in a dissolved state through plasma. The binding of carbon dioxide to hemoglobin is related to the partial pressure of $C{O}_2$. When p$C{O}_2$ is high and p$O_2$ is low as in the tissues, more binding of carbon dioxide occurs whereas, when the p$C{O}_2$ is low and p$O_2$ is high as in the alveoli, dissociation of $C{O}_2$ from carbamino-haemoglobin takes place. RBCs contain a very high concentration of the enzyme, carbonic anhydrase and minute quantities of the same is present in the plasma too. This enzyme facilitates the formation of carbonic acid, as well as its dissociation into protons and bicarbonate ions.