Assertion. `CO_(2)` is carried in the plasma mainly as `HCO_(3)^(-)` ions
Reason. Zinc -containing enzyme carbonic anhydrase of RBCs catalyses the formations fo `HCO_(3)^(-)` ions that enter plasma.

Options

A. Both Assertion and Reason are true and Reason is the correct explanation of Assertion
B. Both Asssertion and Reason are true, but Reason is not the correct explanation of Assertion
C. Assertion is true, but Reason is true
D. both Assertion and Reason are flase.

Answer

A

Explanation

Cells of RBCs contain a zinc-containing enzyme, the carbonic anhydrase. This enzyme accelerates the binding of `CO_(2)` molecules to the blood RBCs about 5000 times.
Due to this, about 70% of carbon dioxide , received by blood from the tissues , entres the RBCs where it reacts with water of form carbonic acid `(H_(2)CO_(3))` . Alomst as rapidly as formed, all carboinc acid of RBCs dissociates into `H^(+) and HCO_(3)^(-)` . then `H^(+)` ions combine with haemoglobin to keep the pH of the blood steady and `HCO_(3)^(-)` diffuse from RBCs into the plsama.