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

Answer: (b)

At the tissue site where partial pressure of $CO_2$ is high due to catabolism, $CO_2$ diffuses into blood (RBCs and plasma) and forms $HCO^{–}_{2}$ and $H^{+}$. At the alveolar site where p$CO_2$ is low, the reaction proceeds in the opposite direction leading to the formation of $CO_2$ and $H_2$O. Thus, $CO_2$ trapped as bicarbonate at the tissue level and transported to the alveoli is released out as $CO_2$.