Question

Question 24
The blood leaving the tissues becomes richer in

(a) carbon dioxide
(b) water
(c) haemoglobin
(d) oxygen

Answer 1

(a) carbon dioxide

The blood leaving the tissues becomes richer in $C{O}_2$. The main artery (aorta) carries oxygenated blood to all the organs of the body from the heart. When the oxygenated blood passes through the capillaries of the body organs/tissues, it gives oxygen to the body cells.

At the same time, carbon dioxide produced during respiration enters into the blood. Thus, deoxygenated (carrying $C{O}_2$) blood leaves the tissues and enters the vena cava, from where they are again passed to the lungs via heart for oxygenation.