Q.118 Botany ⭐ 360° Option Elimination Active
NEET 2024 Botany Question 118 Solution
Topic: Biomolecules · Official NTA Booklet Code T1
Question
The cofactor of the enzyme carboxypeptidase is:
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Verified Against NTA Final Answer Key
Option (3) : Zinc
📚 Biomolecules Easy
📋 Given Parameters & Problem Setup
Enzyme Carboxypeptidase (proteolytic enzyme)
Target Essential metal ion cofactor
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⏱️ Save ~15 seconds The 30-Second Exam Hall Shortcut: ⚡ Carboxypeptidase Metal Ion Fingerprint
Carboxypeptidase and Carbonic anhydrase both strictly require Zinc (Zn²⁺) as their catalytic metal ion cofactor!
1 Recall essential metal cofactors:
2 - Zinc (Zn²⁺): Cofactor for Carboxypeptidase, Carbonic anhydrase, and Alcohol dehydrogenase.
3 - Magnesium (Mg²⁺): Hexokinase, DNA polymerase, RuBisCO, PEPcase.
4 - Iron (Fe²⁺/Fe³⁺): Catalase, Cytochromes.
5 Carboxypeptidase -> Zinc -> Option (3) / C.
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Why You Can 100% Trust This Shortcut: NCERT Biology · Biomolecules (Cofactors and Catalytic Metal Ions)
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Step-by-Step Rigorous Workflow & Mathematical Proof
Step 1
Understand Cofactor Categories
Cofactors are non-protein constituents bound to an enzyme to make it catalytically active. They are divided into three kinds: prosthetic groups, coenzymes, and metal ions.
Step 2
Role of Metal Ions in Catalysis
A number of enzymes require metal ions for their activity which form coordination bonds with side chains at the active site and simultaneously form one or more coordination bonds with the substrate.
Step 3
Identify Specific Ion for Carboxypeptidase
NCERT explicitly states: "For example, zinc is a cofactor for the proteolytic enzyme carboxypeptidase."
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4-Option Deep Scan
360° Option Elimination Engine Key Feature
Diagnose every choice: Know exactly why the right option works and why distractors fail.
1 (1)
✗ Incorrect Verdict & Scientific Reason:
Copper is found in cytochrome c oxidase and tyrosinase, not carboxypeptidase.
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Student Fallacy (Why candidates pick this trap): Copper is found in cytochrome c oxidase and tyrosinase, not carboxypeptidase.
2 (2)
✗ Incorrect Verdict & Scientific Reason:
Iron is the prosthetic cofactor in catalase, peroxidase, and cytochromes.
⚠️
Student Fallacy (Why candidates pick this trap): Iron is the prosthetic cofactor in catalase, peroxidase, and cytochromes.
3 (3)
✓ 100% Correct Verdict & Scientific Reason:
Zinc (Zn²⁺) is the specific metal ion cofactor required by the proteolytic enzyme carboxypeptidase.
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Why this is airtight: None.
4 (4)
✗ Incorrect Verdict & Scientific Reason:
Magnesium is an activator for kinases, RuBisCO, and PEPcase.
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Student Fallacy (Why candidates pick this trap): Magnesium is an activator for kinases, RuBisCO, and PEPcase.
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NTA Trap Alert: Iron vs Zinc in Digestive Enzymes
Confusing catalase (heme/iron) with carboxypeptidase (zinc).
🛡️ How to avoid the -1 mark: Remember: Carboxypeptidase and Carbonic anhydrase both use Zinc.
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Core NEET Syllabus Standard
Biology Core Botany · Biomolecules Standard Benchmark
Core Scientific Principle Tested:
"A number of enzymes require metal ions for their activity which form coordination bonds with side chains at the active site... For example, zinc is a cofactor for the proteolytic enzyme carboxypeptidase."
Syllabus Focus: Prosthetic Groups, Coenzymes, and Metal Ion Cofactors
✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗
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