Biology

Human Immunity and Blood

2,096 Questions

Human immunity and blood questions cover the physiological mechanisms protecting the body against diseases and the components of blood. Topics include blood groups, cell mediated immunity, monoclonal antibodies, and blood coagulation. These biology topics frequently appear in general science sections of competitive exams.

Blood groupsCell mediated immunityMonoclonal antibodiesBlood coagulationCancer immunology

Human Immunity and Blood Questions

Multiple choice biology soldiers of defense blood clotting and healing of wounds coagulation of blood blood clotting

Platelets are a source of ______________.

  1. Fibrinogen

  2. Calcium

  3. Thromboplastin

  4. Haemoglobin
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Thromboplastin is a plasma protein aiding blood coagulation through catalyzing the conversion of prothrombin to thrombin. It is a complex enzyme that is found in brain, lung, and other tissues and especially in blood platelets and that functions in the conversion of prothrombin to thrombin in the clotting of blood—called also thrombokinase.


So, the correct answer is 'Thromboplastin'.

Multiple choice biology soldiers of defense blood clotting and healing of wounds coagulation of blood blood clotting

The anticoagulant most commonly used to store blood in the blood banks is

  1. Sodium nitrate

  2. Sodium fluoride

  3. EDTA

  4. Acid citrate dextrose
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Acid citrate dextrose solution (anticoagulant citrate dextrose solution) is a solution of citric acid, sodium citrate and dextrose in water. It is mainly used as an anticoagulant to preserve blood specimens required for tissue typing because it removes the calcium ion which plays an important role in blood clotting reaction.

Multiple choice biology soldiers of defense blood clotting and healing of wounds coagulation of blood blood clotting

Labile factor is associated with

  1. Blood coagulation

  2. Blood group

  3. Blood immunity

  4. Blood circulation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

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.

Multiple choice biology soldiers of defense blood clotting and healing of wounds coagulation of blood blood clotting

Which clotting factor has been rejected now?

  1. VIII

  2. VII

  3. VI

  4. V
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

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. 

Multiple choice biology soldiers of defense blood clotting and healing of wounds coagulation of blood blood clotting

Read the statements given below and choose the correct sequence of events leading the formation of a blood clot.
(i) Calcium activates an enzyme.
(ii) Fibrin binds platelets to form a 'plug'.
(iii) Thrombin converts fibrinogen to fibrin.
(iv) Platelets and damaged cells release an activator.

  1. (i), (ii), (iii), (iv)

  2. (ii), (i), (iii), (iv)

  3. (iii), (iv), (i), (ii)

  4. (iv), (i), (iii), (ii)
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
The process of blood clotting starts with the release of thromboplastin from damaged cells and platelets. Thromboplastin converts plasma protein prothrombin into thrombin in the presence of calcium ions. Thrombin then converts soluble plasma protein fibrinogen into fibrin which binds platelets to form a clot. 
Therefore, the correct answer is option D. 
Multiple choice biology soldiers of defense blood clotting and healing of wounds coagulation of blood blood clotting

In human, the prothrombin required for blood clotting is produced inside the

  1. Liver

  2. Blood

  3. Bone

  4. Spleen
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Prothrombin is a coagulation or clotting factor that is needed for the normal clotting of blood. A cascade of biochemical events leads to the formation of the final clot. In this cascade, prothrombin is a precursor to thrombin.
Prothrombin is produced in the liver and is modified in the presence of vitamin K.
Therefore, the correct answer is option A.

Multiple choice biology soldiers of defense blood clotting and healing of wounds coagulation of blood blood clotting

Which of the following happens if platelets are absent in blood?

  1. Severe bleeding in case of injury or cuts

  2. Body cannot form clots

  3. Thrombocytopenia

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Platelets are components of blood. They prevent bleeding by activating coagulation mechanisms hence contribute in wound healing. They play an important role in inflammatory and proliferative events. If the platelets are not present in the blood there will be continuous loss of blood by the blood vessels which may prove fatal.

Multiple choice biology soldiers of defense blood clotting and healing of wounds coagulation of blood blood clotting

Blood clot is mainly due to

  1. Plasma and RBC

  2. Plasma and thrombocytes

  3. Heparin and corpuscles

  4. Fibrin and corpuscles
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The presence of calcium and other clotting factors, Factor X activates an enzyme called prothrombin activator. The enzyme prothrombin activator then converts plasma protein prothrombin into thrombin. Thrombin is the enzyme which in turn converts fibrinogen into fibrin. Polymerized fibrin together with platelets(corpuscles) forms a clot at the wound site. Hence blood clot is mainly due to fibrin and corpuscles.

So the correct answer is 'Fibrin and corpuscles'.

Multiple choice biology soldiers of defense blood clotting and healing of wounds coagulation of blood blood clotting

Thromboplastin required for blood clotting is produced by

  1. Platelets

  2. Erythrocytes

  3. Monocytes

  4. Lymphocytes
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Thromboplastin is a plasma protein aiding blood coagulation through catalyzing the conversion of prothrombin to thrombin. It is a complex enzyme that is found in brain, lung, and other tissues and especially in blood platelets and that functions in the conversion of prothrombin to thrombin in the clotting of blood—called also thrombokinase.


So, the correct answer is 'Platelets'.

Multiple choice biology soldiers of defense blood clotting and healing of wounds coagulation of blood blood clotting

The coagulation of blood occurs due to

  1. Destruction of erythrocytes.

  2. Destruction of leucocytes.

  3. Change of fibrinogen into fibrin.

  4. Formation of serum.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
The mechanism of blood clotting involves The presence of calcium and other clotting factors, Factor X activates an enzyme called prothrombin activator. The enzyme prothrombin activator then converts plasma protein prothrombin into thrombin. Thrombin is the enzyme which in turn converts fibrinogen into fibrin. Polymerized fibrin together with platelets forms a clot at the wound site. Hence The coagulation of blood occurs due to change of fibrinogen into fibrin.
So, the correct answer is 'Change of fibrinogen into fibrin'.
Multiple choice biology soldiers of defense blood clotting and healing of wounds coagulation of blood blood clotting

Thrombokinase is produced in

  1. RBC

  2. WBC

  3. Blood vessels

  4. Blood clotting
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Thrombokinase is also known as thromboplastin. It is a complex enzyme which aids in clotting of blood. It is present in platelets and some body tissues. When the platelets aggregate at the site of injury, thrombokinase is released from platelets and damaged tissues. Thrombokinase converts prothrombin into thrombin which acts as an enzyme and converts fibrinogen into fibrin threads. The fibrin threads form a clot at the site of injury. Hence thrombokinase is produced in blood clotting.

So, the correct answer is 'Blood clotting'