Blood is a vital fluid in the human body that is composed of several different components. PLASMA and SERUM are two of these components. PLASMA is a yellowish liquid that makes up about 55% of the total volume of blood and is composed of water, proteins, and other substances. SERUM is the clear liquid that remains after the clotting factors have been removed from the blood. It is composed of proteins, antibodies, and other substances. Both PLASMA and SERUM are important constituents of blood and play an essential role in the functioning of the human body.