Since fibrinogen is always present in the blood, but the blood does not clot, what must normally be absent
A)prothrombin
B)thrombin
C)calcium
D)platelets

Question

Quizplus · Accepted Answer

Thrombin is the enzyme responsible for converting fibrinogen into fibrin during the clotting process. If thrombin were present all the time, blood would clot unnecessarily. Therefore, it is normally absent or inactive in circulating blood until needed for clotting.

Since Fibrinogen Is Always Present in the Blood, but the Blood