Isomerases and Isomer Inter-Conversion — NEET Biology

Correct answer: A — A-iv, B-vi, C-ii, D-iii, E-v, F-i

The core concept is the classification of enzymes based on the type of reactions they catalyse. Let's match each enzyme class from Column I with its definition in Column II as per NCERT: A. Oxidoreductase: "Enzymes which catalyse oxidoreduction between two substrates S and S’". This matches with (iv) Catalyses oxidoreduction between two substrates. B. Transferase: "Enzymes catalysing a transfer of a group, G (other than hydrogen) between a pair of substrate S and S’". This matches with (vi) Catalyses transfer of a group G (other than hydrogen) between a pair of substrates. C. Hydrolase: "Enzymes catalysing hydrolysis of ester, ether, peptide, glycosidic, C-C, C-halide or P-N bonds." This matches with (ii) Catalyses hydrolysis of glycosidic or peptide bonds. D. Lyase: "Enzymes that catalyse removal of groups from substrates by mechanisms other than hydrolysis leaving double bonds." This matches with (iii) Catalyses removal of groups from substrates, leaving double bonds. E. Ligase: "Enzymes catalysing the linking together of 2 compounds, e.g., enzymes which catalyse joining of C-O, C-S, C-N, P-O etc. bonds." This matches with (v) Catalyses the linking together of two compounds with C-O, C-S, or C-N bonds. F. Isomerase: "Includes all enzymes catalysing inter-conversion of optical, geometric or positional isomers." This matches with (i) Catalyses inter-conversion of optical, geometric or positional isomers. Thus, the correct match is A-iv, B-vi, C-ii, D-iii, E-v, F-i. The final answer is A, which correctly pairs each enzyme class with its characteristic reaction type. Concept Recap: Enzymes are classified into six major classes (oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases) based on the specific type of chemical reaction they catalyse.