Question

Assertion (A) Thrombin is essential for blood clotting.
Reason (R) $Ca ^{2+}$ plays an important role in blood clotting.

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

Answer 1

Answer: (B)

Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
Thrombins (formed from inactive prothrombins by enzyme complex thrombokinase) are enzymes which convert inactive fibrinogens in plasma to fibrins which help in blood clotting.
Calcium ions are very important for blood clotting. They help in the formation of intrinsic and extrinsic factors for blood coagulation and thrombins.