Q45. Match the metabolic pathways in Group 1 with the corresponding enzymes in Group 2
| Group 1 | Group 2 |
|---|---|
| P. β-Oxidation Q. Glycolysis R. Gluconeogenesis S. Calvin cycle |
1. Ribulose bisphosphate carboxylase 2. Phosphofructokinase 1 3. Phosphoenol pyruvate carboxykinase 4. Thiolase 5. Phosphofructokinase 2 |
β-Oxidation uses thiolase for fatty acid breakdown, glycolysis relies on phosphofructokinase 1 as its key regulatory enzyme, gluconeogenesis features phosphoenol pyruvate carboxykinase for glucose synthesis, and the Calvin cycle depends on ribulose bisphosphate carboxylase for CO2 fixation. The correct answer for this GATE Life Sciences matching question is option (D).
Group 1-Group 2 Matches
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P. β-Oxidation → 4. Thiolase: Catalyzes the final cleavage step, releasing acetyl-CoA from acyl-CoA chains during mitochondrial fatty acid oxidation.
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Q. Glycolysis → 2. Phosphofructokinase 1: Rate-limiting enzyme converting fructose-6-phosphate to fructose-1,6-bisphosphate, allosterically regulated by ATP/AMP.
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R. Gluconeogenesis → 3. Phosphoenol pyruvate carboxykinase: Converts oxaloacetate to phosphoenolpyruvate (PEP), a key bypass step reversing pyruvate kinase.
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S. Calvin cycle → 1. Ribulose bisphosphate carboxylase: Rubisco fixes CO2 onto RuBP in photosynthesis, the most abundant enzyme on Earth.
Option Analysis
Option (A): P-4, Q-2, R-3, S-5
Incorrect. S (Calvin cycle) mismatches phosphofructokinase 2 (5, a glycolysis regulator variant, not photosynthetic).
Option (B): P-3, Q-2, R-4, S-1
Incorrect. P (β-oxidation) mismatches PEPCK (3, gluconeogenic); R mismatches thiolase (4, lipid-specific).
Option (C): P-3, Q-1, R-5, S-2
Incorrect. P mismatches PEPCK (3); Q mismatches Rubisco (1); R mismatches PFK2 (5).
Option (D): P-4, Q-2, R-3, S-1
Correct—all enzymes align precisely with their signature pathways.
β-oxidation glycolysis gluconeogenesis calvin cycle enzyme matching questions dominate GATE Life Sciences metabolism PYQs, linking Group 1 pathways to Group 2 enzymes like thiolase and phosphofructokinase 1.
Signature Enzymes
β-Oxidation employs thiolase for acetyl-CoA release in fatty acid catabolism. Glycolysis hinges on phosphofructokinase 1 for committed glucose breakdown. Gluconeogenesis uses phosphoenol pyruvate carboxykinase to bypass irreversible steps. Calvin cycle relies on ribulose bisphosphate carboxylase (Rubisco) for carbon fixation.
Exam Strategy
Memorize uniques: Thiolase = lipids only (4); Rubisco = plants (1); PEPCK = glucose-from-noncarb (3); PFK1 = glycolysis pacemaker (2).
| Group 1 | Correct Group 2 | Pathway Role |
|---|---|---|
| P. β-Oxidation | 4. Thiolase | Acetyl-CoA cleavage |
| Q. Glycolysis | 2. Phosphofructokinase 1 | Rate-limiting |
| R. Gluconeogenesis | 3. Phosphoenol pyruvate carboxykinase | PEP formation |
| S. Calvin cycle | 1. Ribulose bisphosphate carboxylase | CO2 fixation |
Target these for CSIR NET—unique enzyme-pathway pairs guarantee full marks.
