Question

Assertion : The process of clotting can occur in absence of all cellular elements except platelets.
Reason :Vitamin $K$ is essential for blood clotting.

• A. If both assertion and reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false
• D. If both assertion and reason are false

Answer 1

Answer: (B)

Activated platelets are essential for blood clotting because several of the cascade reactions take place on the surface of platelets. Vitamin $K$ is essential for production of prothrombin. Prothrombin and many plasma clotting factors are produced in the liver. The liver requires vitamin $K$ to produce prothrombin and several other dotting factors.