Breathing and Exchange of Gases Question 11
11. The majority of carbon dioxide produced by our body cells is transported to the lungs
[2006]
(a) as bicarbonates
(b) as carbonates
(c) attached to hemoglobin
(d) dissolved in the blood
Show Answer
Answer : a
Hints & Solution
(a) Transport of $CO_2$ is much easier than $O_2$ because of the higher solubility of $CO_2$ than $O_2$. Almost $7 %$ of $CO_2$ is transported in dissolved state in plasma. About $23 %$ of the $CO_2$ is transported in the form of carbamino haemoglobin. $70 %$ of $CO_2$ is transported in the form of bicarbonate ions. $CO_2$ reacts with water present in plasma. Carbonic acid is unstable & gives $H^{+}$and $HCO^{3-} . H^{+}$bind with haemoglobin to maintain the $pH$ of blood while $HCO^{3-}$ remain in the blood and carries the $CO_2$ to lungs.
