Breathing and Exchange of Gases Question 9
9. Bulk of carbon dioxide $(CO_2)$ released from body tissues into the blood is present as
[2011M]
(a) bicarbonate in blood plasma and RBCs
(b) free $CO_2$ in blood plasma
(c) $70 %$ carbamino- haemoglobin and $30 %$ as bicarbonate
(d) carbamino-haemoglobin in RBCs
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Answer : a
Hints & Solution
(a) $70 %$ to $75 % CO_2$ is transported as primary buffer of the blood bicarbonate ion $(HCO_3)$ in blood plasma. When $CO_2$ diffuses from tissues into blood then it is acted upon by the enzyme carbonic anhydrase.
