Biology - Body Fluids and Circulation Question with Solution | TestHub

Prothrombin is a plasma protein that acts as a procoagulant (clotting factor), not an anticoagulant.

Antibodies are immunoglobulins involved in defense mechanisms and immunity, not regulators.

Heparin is a natural anticoagulant present in the blood, not a waste product.

Properdin is a globulin protein found in blood plasma that participates in the alternative pathway of the complement system.

Answer: Protein - Properdin