Pantothenic acid, Vitamin B2, Vitamin B6, and folic acid each play distinct roles in key biochemical reactions. This matching question tests understanding of their coenzyme functions in metabolism.

Correct Answer

The correct matching is (B) P-4, Q-1, R-3, S-2. Pantothenic acid (P) links to fatty acid metabolism (4), Vitamin B2 (Q) to electron transport (1), Vitamin B6 (R) to decarboxylation (3), and folic acid (S) to transfer of 1-C units (2).​

Role of Each Vitamin

Pantothenic acid forms coenzyme A (CoA) and acyl carrier protein, essential for fatty acid synthesis, beta-oxidation, and acyl group transfers in energy metabolism. Vitamin B2 (riboflavin) generates flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), which shuttle electrons in the respiratory chain and dehydrogenases. Vitamin B6 (pyridoxine) produces pyridoxal phosphate (PLP), a coenzyme for amino acid decarboxylases, transaminases, and racemases. Folic acid yields tetrahydrofolate (THF), which carries one-carbon units in purine, thymidylate, and methionine synthesis.​

Option Analysis

• (A) P-5, Q-2, R-4, S-1: Incorrect; pantothenic acid does not hydrolyze bonds primarily (5 matches none directly), and mismatches B2 with 1-C transfer while S wrongly pairs with electron transport.​

• (B) P-4, Q-1, R-3, S-2: Correct, as detailed above with precise coenzyme roles aligning each vitamin.​

• (C) P-4, Q-2, R-1, S-3: Wrong; B2 fits electron transport via FAD, not 1-C units, and B6 drives decarboxylation, not electron transport.​

• (D) P-2, Q-1, R-3, S-5: Incorrect; pantothenic acid handles fatty acids via CoA, not 1-C transfer, and folic acid transfers 1-C units, not hydrolysis.​