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Q.30 Botany ⭐ 360° Option Elimination Active
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NEET 2020 Botany Question 30 Solution

Topic: Biomolecules · Official NTA Booklet Code E1
NEET 2020 Botany Question 30: Biochemical Categories: Enzyme Inhibitors, Proteins, Polysaccharides, and Secondary Metabolites

Question

Match the following: (a) Inhibitor of catalytic (i) Ricin activity (b) Possess peptide bonds (ii) Malonate (c) Cell wall material in (iii) Chitin fungi (d) Secondary metabolite (iv) Collagen Choose the correct option from the following: (a) (b) (c) (d)

  1. (1)(ii) (iv) (iii) (i)
  2. (2)(iii) (i) (iv) (ii)
  3. (3)(iii) (iv) (i) (ii)
  4. (4)(ii) (iii) (i) (iv)
✓
Verified Against NTA Final Answer Key
Option (1) : (a)-(ii), (b)-(iv), (c)-(iii), (d)-(i)
📚 Biomolecules Easy
📋 Given Parameters & Problem Setup
Column I (Biochemical Descriptors) (a) Inhibitor of catalytic activity, (b) Possess peptide bonds, (c) Cell wall material in fungi, (d) Secondary metabolite
Column II (Molecules) (i) Ricin, (ii) Malonate, (iii) Chitin, (iv) Collagen
⚡

The 30-Second Exam Hall Shortcut: ⚡ "Malonate = Competitive Inhibitor, Collagen = Protein (Peptide), Chitin = Fungal Wall"

⏱️ Save ~25 seconds

Malonate is the classic competitive inhibitor of succinate dehydrogenase ((a)-(ii)). Collagen is an abundant extracellular matrix protein with peptide bonds ((b)-(iv)). Chitin is the structural polysaccharide in fungal cell walls ((c)-(iii)). Ricin is a ribosome-inactivating toxic secondary metabolite ((d)-(i)). Pattern (ii), (iv), (iii), (i) matches Option (1) instantly!

1 Match (a) Inhibitor of catalytic activity -> (ii) Malonate (competitive inhibitor mimicking succinate).
2 Match (b) Possess peptide bonds -> (iv) Collagen (most abundant animal protein).
3 Match (c) Cell wall material in fungi -> (iii) Chitin (homopolymer of N-acetylglucosamine).
4 Match (d) Secondary metabolite -> (i) Ricin (plant toxin from Ricinus communis).
5 Match pattern (ii), (iv), (iii), (i) -> Select Option (1).
🛡️
Why You Can 100% Trust This Shortcut: NCERT Biology · Biomolecules (Enzymes, Proteins & Secondary Metabolites: Inhibition of succinic dehydrogenase by malonate which closely resembles the substrate succinate in structure is competitive inhibition; Collagen is the most abundant protein in animal world possessing peptide bonds; Chitin is a complex polysaccharide in fungal cell wall; Ricin is a secondary metabolite toxin).
📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Biochemical Characterization of Target Molecules

- (a) Inhibitor of catalytic activity: Malonate (−OOC−CH2−COO−-\text{OOC}-\text{CH}_2-\text{COO}^-) is a structural analog of succinate (−OOC−CH2−CH2−COO−-\text{OOC}-\text{CH}_2-\text{CH}_2-\text{COO}^-). It binds reversibly to the active site of the Krebs cycle enzyme succinate dehydrogenase, competitively inhibiting catalytic conversion to fumarate. - (b) Possess peptide bonds: Collagen is a fibrous structural triple-helix protein (the most abundant protein in the animal kingdom), synthesized as linear polymers of amino acids linked covalently by peptide bonds. - (c) Cell wall material in fungi: Chitin is a tough, nitrogen-containing structural homopolysaccharide composed of unbranched chains of N-acetylglucosamine (NAG) linked by β\beta-(1,4)-glycosidic bonds, forming the cell walls of fungi and exoskeletons of arthropods. - (d) Secondary metabolite: Ricin is a potent lectin ribosome-inactivating protein synthesized in the seeds of the castor bean (*Ricinus communis*), classified explicitly as a toxin secondary metabolite in NCERT.

Catalytic Inhibitor  ⟺  Malonate[(a)→(ii)]Peptide bonds  ⟺  Collagen[(b)→(iv)]Fungal cell wall  ⟺  Chitin[(c)→(iii)]Secondary metabolite  ⟺  Ricin[(d)→(i)]\begin{aligned} \text{Catalytic Inhibitor} &\iff \text{Malonate} \quad [\text{(a)} \to \text{(ii)}] \\ \text{Peptide bonds} &\iff \text{Collagen} \quad [\text{(b)} \to \text{(iv)}] \\ \text{Fungal cell wall} &\iff \text{Chitin} \quad [\text{(c)} \to \text{(iii)}] \\ \text{Secondary metabolite} &\iff \text{Ricin} \quad [\text{(d)} \to \text{(i)}] \end{aligned}
Step 2

Option Alignment

Matching sequence is: (a)-(ii), (b)-(iv), (c)-(iii), (d)-(i). This corresponds precisely to Option (1).

⭐

360° Option Elimination Engine Key Feature

Diagnose every choice: Know exactly why the right option works and why distractors fail.

4-Option Deep Scan
1 A
✓ 100% Correct
Verdict & Scientific Reason:

Correct. Accurately matches all 4 biochemical categories with their textbook representatives.

💡
Why this is airtight: None. Candidate recalls the classic NCERT biomolecules examples.
2 B
✗ Incorrect
Verdict & Scientific Reason:

Incorrect. Assigns chitin to catalytic inhibitor and collagen to fungal cell wall.

⚠️
Student Fallacy (Why candidates pick this trap): Gross misalignment of proteins and polysaccharides.
3 C
✗ Incorrect
Verdict & Scientific Reason:

Incorrect. Misidentifies chitin as an enzyme inhibitor.

⚠️
Student Fallacy (Why candidates pick this trap): Confusing competitive inhibitors with structural carbohydrates.
4 D
✗ Incorrect
Verdict & Scientific Reason:

Incorrect. Assigns chitin to peptide bonds and ricin to fungal cell walls.

⚠️
Student Fallacy (Why candidates pick this trap): Confusing secondary metabolites with cell wall polymers.
⚠️

NTA Trap Alert: Malonate vs Malate Confusion Trap

Malate is a normal intermediate in the Krebs cycle. Malonate (with three carbons) is the competitive inhibitor of succinate dehydrogenase. Do not confuse the metabolite (malate) with the inhibitor (malonate).

🛡️ How to avoid the -1 mark: Remember: MaloNATE inhibits Succinate Dehydrogenase.
📖

Core NEET Syllabus Standard

NEET / NCERT Biology · Biomolecules Standard Benchmark
Core Scientific Principle Tested:

"Malonate is a competitive enzyme inhibitor, collagen has peptide bonds, chitin is fungal wall material, and ricin is a secondary metabolite."

Syllabus Focus: Classification of Biomolecules and Enzymes
✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

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