AIIMS 2013 Biology Question Paper for free online practice with solutions

Blood is the medium of transport of O2 and CO2- Nearly 20-25% of CO2 is transported by RBCs as carbaminohaemoglobin whereas 70% of it is carried as bicarbonate through plasma. About 7% of CO2 is carried in dissolved state through plasma. The largest fraction of C02 is converted to bicarbonate ions (HCO3) and transported in plasma. When CO2 diffuses into the RBCs, it combines with H2O , forming carbonic acid (H2CO3).H2CO3 is unstable and quickly dissociates into hydrogen ions and bicarbonate ions.