Question
Biology Question on Digestion and absorption
Vitamin K is required for
A
change of prothrombin into thrombin
B
synthesis of prothrombin
C
change of fibrinogen to fibrin
D
formation of thromboplastin.
Answer
synthesis of prothrombin
Explanation
Solution
Thromboplastin, a lipoprotein, helps in clot i formation. Thromboplastin helps in the formation of an enzyme prothrombinase. This enzyme inactivates heparin and it also converts the inactive plasma protein prothrombin into its active form, thrombin. Both the changes require calcium ions. Thrombin converts fibrinogen molecule to insoluble fibrin. The fibrin monomers polymerize to form long, sticky fibres. The fibrin threads form a fine network over the wound and j trap blood corpuscles (RBCs, WBCs, platelets) to form a crust, the clot.