NEET Biology Breathing And Exchange Of Gases Based Practice Questions & Answers with Viewers Discussion and Detailed Explanation

Answer: (c)

About 70% of CO₂ released diffuses into the plasma and then into the RBCs. Here, it combines with water to form carbonic acid. Carbonic acid dissociates into bicarbonate and hydrogen ions. Hydrogen ions are picked up by proteins and a small amount of bicarbonate ions is transported in the RBCs, whereas most of them diffuse into the plasma to be carried by it. About 7% of CO₂ is transported as dissolved in plasma and 23% of CO₂ combines with Hb to form carbaminohaemoglobin.

$CO_2  + H_2 O  ⇌↖{carbonic}↙{anhydrase} H_2 CO_3(carbonic acid)$

$H_2 CO_3 ⇌ H^{+} +  HCO_3^{-}(bicarbonate ion)$