Conversion of prekallikrein to kallikrein requires which clotting factor -

Conversion of prekallikrein to kallikrein
requires which clotting factor -
a) XIII
b) XII
c) XI
d) X

Correct Answer - B
Ans. is’b’i.e., XII
[Rel Essential of medical physiology p. 612]
Initiation of intrinsic coagulation pathway occurs when factor XII is
exposed to negatively charged surface.
This leads to activation offactor XII to XIIa.
Factor XIIa can then hydrolyze prekallikrein to kallikrein, which in
turn activates more XII to XIIa.