Which of the following vitamins is mainly responsible for blood coagulation in human being ?

Question

UnlockIAS · Accepted Answer

Correct — A, Vitamin K. Vitamin K is the essential cofactor for the liver's synthesis of several clotting factors — prothrombin (Factor II) and Factors VII, IX and X — via the gamma-carboxylation of their glutamate residues. Without vitamin K these coagulation factors are not activated, blood cannot clot normally, and a bleeding tendency results. That is why vitamin K is the vitamin mainly responsible for blood coagulation — indeed the 'K' comes from the German word Koagulation.

Why the other options are wrong — (b) Vitamin E is a fat-soluble antioxidant that protects cell membranes from oxidative damage; it has no direct role in the clotting cascade.  (c) Vitamin A supports vision (rhodopsin) and epithelial/immune health; its deficiency causes night blindness, not a clotting defect.  (d) Vitamin C is needed for collagen synthesis; its deficiency (scurvy) causes bleeding gums through WEAK COLLAGEN in vessel walls — a tempting trap — but it is not the coagulation-factor vitamin. Clotting depends on vitamin K.

Concept: Vitamin K is a fat-soluble vitamin required for the post-translational gamma-carboxylation of clotting factors II (prothrombin), VII, IX and X, plus anticoagulant proteins C and S. Dietary vitamin K1 (phylloquinone) comes mainly from green leafy vegetables, while K2 (menaquinone) is produced by gut bacteria. Newborns receive a prophylactic vitamin K dose to prevent haemorrhagic disease of the newborn, and the anticoagulant drug warfarin works by antagonising vitamin K.

State PCS 2020 Q99 — Science & Technology PYQ with Answer

State PCS 2020 Q99 — Science & Technology PYQ with Answer