Body Fluids and Circulation Question 11
11. What is true about RBCs in humans? [2010]
(a) They carry about 20-25 per cent of $CO_2$.
(b) They transport 99.5 per cent of $O_2$.
(c) They transport about 80 per cent oxygen only and the rest 20 per cent of it is transported in dissolved state in blood plasma.
(d) They do not carry $CO_2$ at all.
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Answer : a
Hints & Solutions
(a) Blood transports oxygen from respiratory organs to the tissue cells and also transports carbon dioxide from the tissue cells to the respiratory membrane. About $97 %$ of oxygen is transported by RBCs in the blood while the remaining three percent of oxygen is carried in a dissolved state through plasma. Nearly 20 $25 %$ of carbon dioxide is transported by RBCs whereas $70 %$ is carried as bicarbonate. About $7 %$ of $CO_2$ is carried in dissolved state through plasma.
