Final answer:
Fibrinogen is the plasma protein responsible for polymerizing into fibrin during the blood clotting process, aiding in wound healing and preventing excess blood loss.
Step-by-step explanation:
The plasma protein that polymerizes to form fibrin during clotting is called fibrinogen. Fibrinogen, which is produced by the liver, is one of the least abundant plasma proteins, but it plays a critical role in blood clotting. During the coagulation phase, fibrinogen is converted to fibrin through the action of the enzyme thrombin, following the activation of the coagulation factors by the intrinsic or extrinsic pathway. Fibrin then forms a mesh-like structure that traps platelets and erythrocytes, effectively creating a clot and preventing further blood loss. This clotting mechanism is vital in wound healing and maintaining hemostasis.