Question

Vitamin K during blood coagulation is required for

• A. change of fibrinogen to fibrin
• B. change of prothrombin to thrombin
• C. formation of prothrombin
• D. all of the above

Answer 1

The correct option is C formation of prothrombin

Prothrombin is formed by the liver. Vitamin K is required by the liver for the formation of prothrombin. If the liver fails to produce prothrombin then the concentration of prothrombin falls in the plasma, which leads to failure in blood coagulation.

The prothrombin activator (thrombokinase), in the presence of calcium ions, causes conversion of prothrombin to thrombin.
The thrombin acts as an enzyme to convert fibrinogen into fibrin fibres that forms a mesh called clot.