Blood clotting requires the presence of the following catalyst:

Appeared in: IGNOU PB Bsc Entrance-2022

Explanation

Calcium ions (Ca++) are designated as Factor IV in the blood coagulation cascade.
Ca++ acts as a critical cofactor, binding to phospholipids on the surface of platelets and clotting factors.
This binding is essential for the activation of multiple clotting factors, including the conversion of prothrombin (Factor II) into its active form, thrombin, which is a key step in forming a clot.

Option A: Fluorine (F) is a trace element whose primary role is in the mineralization of bones and teeth, making them resistant to decay.
Option B: Chromium (Cr) is involved in macronutrient metabolism and enhances the function of insulin to promote glucose utilization.
Option D: Iron (Fe+++) is a central component of hemoglobin and myoglobin, essential for oxygen transport and storage, not for the clotting cascade itself.

Clinical Relevance

Nursing practice connection: Knowing Role of minerals in blood coagulation helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Nurses must monitor for signs of hypocalcemia (e.g., muscle twitching, Chvostek's/Trousseau's signs) in patients receiving massive blood transfusions, as the citrate anticoagulant in stored blood binds to and depletes free calcium.
Patients with certain conditions like hypoparathyroidism may have chronic hypocalcemia, increasing their risk of bleeding.
What if? If a patient has severe liver disease, they may have impaired clotting not due to calcium deficiency, but because the liver synthesizes most protein clotting factors (like Prothrombin and Fibrinogen). In this case, administering calcium alone would be ineffective and vitamin K or fresh frozen plasma might be needed.

How to Approach the Question

First, identify the core physiological process in the question: 'blood clotting'.
The question asks for a 'catalyst', which in a biological context often refers to an enzyme or a necessary cofactor.
Recall or deduce the key components of the coagulation cascade. This process involves various protein factors (I-XIII) and essential ions.
Evaluate each option's primary biological role. Calcium (Ca++) is widely known as Factor IV and is a key cofactor in the cascade.
Contrast this with the other options: Fluorine is for teeth, Iron is for hemoglobin/oxygen transport, and Chromium is for glucose metabolism.
Select the ion that is directly and essentially involved in the cascade reactions, which is Ca++.

Concept Tested & Keywords

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E6 Biochemistry U Satyanarayana— Part 2 (pp 421-820 of 840) pp. 21-23, 39-41

E6 Biochemistry U Satyanarayana— Part 1 (pp 26-420 of 840) p. 183-185

Practise the full IGNOU PB Bsc Entrance-2022

Attempt every question from this paper in a timed mock, then review the full solution for each one.