CBSE Class 10 Answered

Blood is made up of plasma and cells. Blood has important features which make it suitable as a transporting medium.

For example, the RBCs of blood have the respiratory pigment hemoglobin which has great affinity for oxygen and hence helps in carrying oxygen. Hemoglobin facilitates transportation of oxygen by reversibly binding to this respiratory gas and greatly increasing its solubility in blood. In contrast, carbon dioxide is almost entirely transported extracellularly dissolved in plasma as bicarbonate ion.

Also the white blood cells of blood can reach the site of infection when needed and also produce antibodies according to the body's requirement.

Blood is more viscous than water.

Also blood has the platelets and fibrinogen which will help in clotting in case of an injury.

All these features are not present in water, so it cannot perform any of the important functions of transportation.