Class 11 NEET Biology Breathing and Exchange of Gases

(a) : Carbon dioxide is carried by the blood in three forms : physical solution, bicarbonate ions and carbamino-haemoglobin. A very small amount of carbon dioxide dissolves in the plasma and is carried as a physical solution. About 70% of carbon dioxide released by respiring tissue cells diffuses into the plasma and then into the red blood corpuscles. Here, CO2 combines with water to form carbonic acid. Carbonic acid dissociates into bicarbonate and hydrogen ions.