Blood is the medium of transport for O2 and CO2. About 97 per cent of O2 is transported by RBCs in the blood.
The remaining 3 per cent of O2 is carried in a dissolved state through the plasma.
Nearly 20-25 per cent of CO2 is transported by RBCs whereas 70 per cent of it is carried as bicarbonate. About 7 per cent of CO2 is carried in a dissolved state through plasma.