NEET Zoology Gas Exchange MCQ Question
Which combination of statements about gas exchange is correct?
CO2 diffuses into blood where it forms bicarbonate. 2. The enzyme carbonic anhydrase is present in RBCs. 3. CO2 is expelled from the lungs when the pressure is higher inside than outside.
CO2 is only transported in dissolved form in plasma. 2. Bicarbonate is formed only at the alveoli. 3. Gas exchange occurs without any enzyme involvement.
Oxygen is primarily transported as bicarbonate. 2. At the alveolar site, high pCO2 promotes diffusion into blood. 3. The presence of carbonic anhydrase reduces the efficiency of gas exchange.
CO2 is not involved in gas exchange. 2. Air enters lungs due to increased intra-pulmonary pressure. 3. Bicarbonate formation occurs only at the tissues.
Correct Answer
Detailed Explanation
Statement 1 is correct as CO2 diffuses into the blood and is converted into bicarbonate. Statement 2 is correct as carbonic anhydrase facilitates this reaction in RBCs. Statement 3 is correct as CO2 is expelled when the pulmonary pressure exceeds atmospheric pressure, facilitating expiration.
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