1. What is the primary role of platelets in blood clotting?
A) Oxygen transport
B) Initiating clot formation
C) Fighting infections
D) Plasma protein synthesis
Answer: B) Initiating clot formation
Explanation: Platelets are responsible for initiating the formation of a blood clot by adhering to the injury site and releasing chemicals that trigger clotting.
2. Which of the following proteins is involved in the final step of blood clotting?
A) Fibrinogen
B) Prothrombin
C) Factor VIII
D) Thromboplastin
Answer: A) Fibrinogen
Explanation: Fibrinogen is converted into fibrin, which forms the mesh-like structure of the clot in the final stage of coagulation.
3. Which coagulation factor is also known as the anti-hemophilic factor?
A) Factor VII
B) Factor IX
C) Factor VIII
D) Factor X
Answer: C) Factor VIII
Explanation: Factor VIII is known as the anti-hemophilic factor. A deficiency in this factor leads to hemophilia A.
4. What activates the clotting cascade in the intrinsic pathway?
A) Exposure to tissue factor
B) Collagen fibers at the injury site
C) Platelet aggregation
D) Thromboplastin release
Answer: B) Collagen fibers at the injury site
Explanation: The intrinsic pathway of coagulation is triggered when platelets come in contact with exposed collagen fibers in the vessel wall.
5. Which of the following is not a step in the clotting process?
A) Vasoconstriction
B) Platelet aggregation
C) Protein synthesis by liver
D) Hemolysis
Answer: D) Hemolysis
Explanation: Hemolysis refers to the destruction of red blood cells, which is not a step in the clotting process.
6. Which of the following factors is responsible for converting prothrombin into thrombin?
A) Factor V
B) Factor X
C) Factor II
D) Factor XIII
Answer: B) Factor X
Explanation: Factor X is activated during the coagulation cascade and plays a key role in converting prothrombin (Factor II) into thrombin.
7. What is the role of thrombin in blood clotting?
A) Breaks down fibrinogen
B) Activates fibrin to form clot
C) Inhibits clot formation
D) Reverses the clotting process
Answer: B) Activates fibrin to form clot
Explanation: Thrombin converts fibrinogen into fibrin, which forms the insoluble mesh that helps seal the wound.
8. What triggers the extrinsic pathway of blood clotting?
A) Tissue factor (TF) exposure
B) Collagen exposure
C) Activation of platelets
D) Release of thrombin
Answer: A) Tissue factor (TF) exposure
Explanation: The extrinsic pathway is triggered when tissue factor (TF), released by damaged tissue, interacts with Factor VII.
9. Which vitamin is essential for the synthesis of clotting factors?
A) Vitamin A
B) Vitamin B12
C) Vitamin C
D) Vitamin K
Answer: D) Vitamin K
Explanation: Vitamin K is essential for the synthesis of clotting factors II, VII, IX, and X in the liver.
10. Which of the following statements about fibrinolysis is true?
A) It is the process that stops the bleeding
B) It is the breakdown of clots
C) It prevents clot formation
D) It occurs immediately after clot formation
Answer: B) It is the breakdown of clots
Explanation: Fibrinolysis is the process where the clot is broken down after the wound has healed, primarily involving plasminogen and plasmin.
11. Which factor is also called the “Stuart-Prower factor”?
A) Factor IX
B) Factor VIII
C) Factor X
D) Factor XI
Answer: C) Factor X
Explanation: Factor X, also known as the Stuart-Prower factor, plays a key role in the common pathway of coagulation.
12. What is the primary action of factor XIII in blood clotting?
A) Converts prothrombin to thrombin
B) Stabilizes the fibrin clot
C) Activates platelets
D) Initiates the intrinsic pathway
Answer: B) Stabilizes the fibrin clot
Explanation: Factor XIII crosslinks fibrin strands to stabilize and strengthen the clot, preventing premature dissolution.
13. Hemophilia A is a deficiency of which coagulation factor?
A) Factor IX
B) Factor VIII
C) Factor V
D) Factor X
Answer: B) Factor VIII
Explanation: Hemophilia A is caused by a deficiency or dysfunction of Factor VIII, which impairs the clotting process.
14. What is the role of von Willebrand factor in blood clotting?
A) Activates thrombin
B) Stabilizes Factor X
C) Mediates platelet adhesion
D) Breaks down fibrinogen
Answer: C) Mediates platelet adhesion
Explanation: Von Willebrand factor (vWF) facilitates platelet adhesion to the damaged vessel wall during clot formation.
15. Which of the following is NOT involved in the intrinsic pathway of coagulation?
A) Factor XII
B) Factor IX
C) Factor VII
D) Factor XI
Answer: C) Factor VII
Explanation: Factor VII is involved in the extrinsic pathway, not the intrinsic pathway of coagulation.
16. What is the role of calcium ions (Ca²⁺) in blood clotting?
A) Activates fibrinogen
B) Facilitates the conversion of prothrombin to thrombin
C) Breaks down fibrin
D) Inhibits platelet aggregation
Answer: B) Facilitates the conversion of prothrombin to thrombin
Explanation: Calcium ions are crucial in many steps of the clotting cascade, especially in the conversion of prothrombin to thrombin.
17. What happens during the formation of a blood clot?
A) Platelets form a plug
B) Prothrombin is converted to thrombin
C) Fibrinogen is converted to fibrin
D) All of the above
Answer: D) All of the above
Explanation: All these events occur in the blood clotting process, which involves platelet aggregation, prothrombin conversion to thrombin, and fibrinogen conversion to fibrin.
18. What is the first step in the process of blood coagulation?
A) Platelet aggregation
B) Formation of fibrin
C) Activation of factor X
D) Vasoconstriction
Answer: A) Platelet aggregation
Explanation: Platelet aggregation is the first step, where platelets adhere to the site of injury and form a temporary plug.
19. Which of the following is a characteristic of blood clot formation?
A) It involves only platelets
B) It only occurs in veins
C) It results in the conversion of fibrinogen into fibrin
D) It requires oxygen to be present
Answer: C) It results in the conversion of fibrinogen into fibrin
Explanation: The conversion of fibrinogen into fibrin is a critical part of clot formation, where fibrin forms a mesh that stabilizes the clot.
20. Which factor is involved in the common pathway of coagulation?
A) Factor XI
B) Factor IX
C) Factor X
D) Factor VIII
Answer: C) Factor X
Explanation: Factor X is involved in the common pathway of coagulation, where it is activated and participates in the conversion of prothrombin to thrombin.
21. Which of the following coagulation factors is Vitamin K-dependent?
A) Factor I
B) Factor VII
C) Factor XIII
D) Factor IV
Answer: B) Factor VII
Explanation: Vitamin K is essential for the synthesis of several coagulation factors, including Factor VII.
22. What is the purpose of the clot retraction mechanism?
A) To dissolve the clot
B) To decrease the size of the clot
C) To stabilize the clot
D) To prevent platelet aggregation
Answer: B) To decrease the size of the clot
Explanation: Clot retraction helps to compact and reduce the size of the clot, aiding in wound closure.
23. The term “hemophilia” refers to a genetic disorder that primarily affects which group of individuals?
A) Males
B) Females
C) Both males and females equally
D) Children under 5 years
Answer: A) Males
Explanation: Hemophilia is an X-linked recessive disorder, which means it primarily affects males.
24. Which factor is activated by thromboplastin in the extrinsic pathway?
A) Factor VII
B) Factor IX
C) Factor X
D) Factor V
Answer: A) Factor VII
Explanation: Thromboplastin activates Factor VII in the extrinsic pathway, initiating the coagulation process.
25. What is the function of plasminogen in the clotting process?
A) Converts fibrinogen into fibrin
B) Converts plasmin into fibrinogen
C) Breaks down fibrin
D) Inactivates prothrombin
Answer: C) Breaks down fibrin
Explanation: Plasminogen is converted into plasmin, which breaks down fibrin during fibrinolysis, allowing the clot to dissolve once healing is complete.
26. What is the role of the “thromboplastin” factor?
A) Converts fibrinogen to fibrin
B) Activates Factor VII in the extrinsic pathway
C) Breaks down the clot
D) Inhibits platelet aggregation
Answer: B) Activates Factor VII in the extrinsic pathway
Explanation: Thromboplastin (also called tissue factor) activates Factor VII, which starts the extrinsic clotting pathway.
27. In which pathway do both intrinsic and extrinsic pathways meet?
A) Common pathway
B) Fibrinolytic pathway
C) Inflammatory pathway
D) Coagulation cascade
Answer: A) Common pathway
Explanation: The intrinsic and extrinsic pathways converge in the common pathway at Factor X, which plays a central role in coagulation.
28. What is the final product of the blood coagulation cascade?
A) Platelet plug
B) Fibrin mesh
C) Thromboplastin
D) Collagen fibers
Answer: B) Fibrin mesh
Explanation: The final product of the coagulation cascade is a fibrin mesh, which stabilizes the blood clot.
29. Which factor is also called the “Hageman factor”?
A) Factor XII
B) Factor IX
C) Factor VIII
D) Factor X
Answer: A) Factor XII
Explanation: Factor XII is known as the Hageman factor and is involved in initiating the intrinsic pathway of coagulation.
30. What is the effect of aspirin on blood clotting?
A) It stimulates clot formation
B) It promotes platelet aggregation
C) It inhibits platelet aggregation
D) It accelerates fibrin breakdown
Answer: C) It inhibits platelet aggregation
Explanation: Aspirin inhibits the function of platelets by blocking the enzyme cyclooxygenase, reducing clot formation.
