Assertion : Thrombin neressary to initiate blood coagulation.
Reason : Thrombin helps in the formation of thromboplastins.

Options

A. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
B. If both the assertion and reason are true but the reason is not a correct explanation of the assertion
C. If the assertion and reason are false
D. If the assertion is false but reason is true

Answer

C

Explanation

Blood coagulation is brought about by the hydrolysis of soluble protein fibrinogen to insoluble fibrin. This reaction is catalysed by the enzyme thrombin. Thrombin occurs in normal blood as an inactive globulin called prothrombin which is activated to thrombin by the action of another enzyme called prothrombinase before blood coagulation starts. Thromboplastins are the coagulation promoting substances released from clumped platelets and damaged tissue, which helps in the formation of the enzyme prothrombinase.