Questions & Answers

Plasma without clotting factor is known as
A. Serum
B. Fibrinogen
C. Albumin
D. Both A and B

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Hint: Human blood is composed of both liquid and solid parts. The liquid part is called plasma or matrix and the solid part is the blood corpuscles.
Blood exhibits clotting properties due to the presence of certain clotting factors. There are a total of thirteen clotting factors discovered to date inside the human blood.

Complete answer:
The matrix of the blood is called plasma. It is pale yellow in colour due to the presence of a pigment called bilirubin.
The major composition of the plasma is water and the remaining portion comprises solid parts including proteins. Plasma proteins are mainly of four types namely - albumin, globulin, prothrombin and fibrinogen. All these plasma proteins are produced by the liver except for some kinds of globulins.
Albumin is responsible for maintaining the blood colloid osmotic pressure. Globulin is responsible for the defence mechanism of the body. Prothrombin and fibrinogen are the plasma proteins which are responsible for the clotting of blood.
The thirteen clotting factors are also produced within the liver itself. The major blood clotting factors are prothrombin and fibrinogen. Blood without blood corpuscles is called plasma and plasma without clotting factors is called serum. The serum is a pale yellow coloured liquid that oozes from the clot. Antibodies are found in serum.

Hence, the correct answer is option (A).

Note: During an injury, injured tissue secretes some proteins called thromboplastins. This thromboplastin reacts with plasma proteins in the presence of calcium ions to form prothrombinase. Prothrombinase then converts inactive prothrombin into active thrombin form. This thrombin then converts fibrinogen to fibrin network. This fibrin network along with trapped blood corpuscles forms the blood clot.