Tag: biology

Blood serum is the component of blood that has neither a blood cell nor a clotting factor. Serum includes all proteins not used in blood clotting (coagulation) and all the electrolytes, antibodies, antigens, hormones, and any exogenous substances (e.g., drugs and microorganisms). Hence, serum does not clot. Thus, the correct answer is option A.

In blood, platelets produce thromboplastin only at the site of injury and not in the normal condition which initiates the process of blood clotting. There is an another factor or protein called fibrinogen. When it makes contact with oxygen, it polymerizes to fibrin wires, creating a heap of fibrin wires, in which the various blood cells get caught, thus clogging the wound. Because all the oxygen in the blood is already bound to haemoglobin (red cells), it can't interact with the fibrinogen, thus cannot create a clot. Thus, the correct answer is option C.

Coagulation (blood clotting) is a complex process that involves a positive feedback system. The factors involved are-
Factor I Fibrinogen
Factor II Prothrombin
Factor III Tissue Factor (Thromboplastin)
Factor IV Calcium
Factor V Labile factor, proaccelerin, Ac-globulin
Factor VII Stable factor, proconvertin
Factor VIII Antihaemophilic globulin (AHG), Antihaemphilic factor A 
Factor IX Christmas factor, plasma thromboplastin component
Factor X Stuart power factor
Factor XI Plasma thromboplastin antecedent
Factor XII Hageman factor
Factor XIII Fibrin stabilising factor
Vitamin K is essential for synthesis of factors II, VII, IX and X.
Their numbers represent the order in which they were discovered.

Clotting factor VIII is the antihemophilic factor while factor VII serves as an accelerator of serum prothrombin conversion. Clotting factor V is proaccelerin. Clotting factor VI was once considered to have clotting function but is now rejected. Thus, the correct answer is C. 

One of the initial steps in blood coagulation is the release of thromboplastin that interacts with other clotting factors and calcium ions. Fibrinogen is a soluble blood protein that becomes insoluble and forms fibrin strands during last steps of clotting. Bilirubin is the breakdown product of hemoglobin. Thus, the correct answer is C.

Heparin is a natural anticoagulant in the body. Hirudin is an anticoagulant produced by leech while sucking the blood of the host. EDTA acts as an anticoagulant by removing calcium ions from the blood and thus chelates with them.

Heparin is a natural anticoagulant produced in the liver and helps in checking the clotting of blood inside blood vessels. 

Blood clotting (coagulation) is the process by which blood vessels repair ruptures after injury. Calcium works together with vitamin K and a protein, called as fibrinogen in the clotting cascade, which forms fibrin. The fibrin hardens very quickly to form a scab over the wound. 

Prothrombin is a plasma protein which is converted into thrombin in the presence of thromboplastin released by platelets at the site of injury. The thrombin then converts protein fibrinogen into insoluble fibrin and thus aids in blood clotting.