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Q.148 Botany ⭐ 360° Option Elimination Active
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NEET 2021 Botany Question 148 Solution

Topic: Biomolecules · Official NTA Booklet Code M1
NEET 2021 Botany Question 148: Covalent Bonds Linking Monomers in Biological Macromolecules

Question

Match List - I with List - II. (a) Protein (i) C=C double bonds (b) Unsaturated fatty acid (ii) Phosphodiester bonds (c) Nucleic acid (iii) Glycosidic bonds (d) Polysaccharide (iv) Peptide bonds List - I List - II Choose the correct answer from the options given below. (a) (b) (c) (d)

  1. (1)(iv) (i) (ii) (iii)
  2. (2)(i) (iv) (iii) (ii)
  3. (3)(ii) (i) (iv) (iii)
  4. (4)(iv) (iii) (i) (ii)
✓
Verified Against NTA Final Answer Key
Option (1) : (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii)
📚 Biomolecules Easy
📋 Given Parameters & Problem Setup
List I (Biomolecules) (a) Protein, (b) Unsaturated fatty acid, (c) Nucleic acid, (d) Polysaccharide
List II (Bonds) (i) C = C double bonds, (ii) Phosphodiester bonds, (iii) Glycosidic bonds, (iv) Peptide bonds
⚡

The 30-Second Exam Hall Shortcut: ⚡ Instant Biochemical Bond Matching!

⏱️ Save ~15 seconds

Proteins = Peptide bonds (a-iv); Unsaturated fatty acids = C=C double bonds (b-i); Nucleic acids = Phosphodiester bonds (c-ii); Polysaccharides = Glycosidic bonds (d-iii)! Gives (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii)   ⟹  \implies Option (1)!

1 (a) Protein: Formed of amino acids linked by Peptide bonds (−CO−NH−-CO-NH-)   ⟹  \implies (iv).
2 (b) Unsaturated fatty acid: Contain one or more Carbon-Carbon double bonds (C=CC=C)   ⟹  \implies (i).
3 (c) Nucleic acid: Nucleotides linked by 3′−5′3'-5' Phosphodiester bonds   ⟹  \implies (ii).
4 (d) Polysaccharide: Monosaccharides linked by Glycosidic bonds   ⟹  \implies (iii).
5 Match Option (1).
🛡️
Why You Can 100% Trust This Shortcut: Canonical NCERT Biomolecules on Nature of Bonds Linking Monomers in a Polymer.
📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Biochemical Nature of Macromolecular Linkages

Biopolymers are assembled from specific building blocks via characteristic condensation bonds:

Protein:Amino acids linked via −CO−NH− (Peptide bonds)  ⟹  (a)-(iv)Unsaturated Fatty Acid:Aliphatic chains with one or more −C=C− double bonds  ⟹  (b)-(i)Nucleic Acid:3′−5′ diester bond of phosphate group (Phosphodiester bonds)  ⟹  (c)-(ii)Polysaccharide:Dehydration between adjacent monosaccharide rings (Glycosidic bonds)  ⟹  (d)-(iii)\begin{aligned} \text{\textbf{Protein:}} & \quad \text{Amino acids linked via } -\text{CO}-\text{NH}- \text{ (Peptide bonds)} \implies \text{(a)-(iv)} \\[4pt] \text{\textbf{Unsaturated Fatty Acid:}} & \quad \text{Aliphatic chains with one or more } -\text{C}=\text{C}- \text{ double bonds} \implies \text{(b)-(i)} \\[4pt] \text{\textbf{Nucleic Acid:}} & \quad 3'-5' \text{ diester bond of phosphate group (Phosphodiester bonds)} \implies \text{(c)-(ii)} \\[4pt] \text{\textbf{Polysaccharide:}} & \quad \text{Dehydration between adjacent monosaccharide rings (Glycosidic bonds)} \implies \text{(d)-(iii)} \end{aligned}
Step 2

Option Alignment

Matching (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii) points uniquely 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 1
✓ 100% Correct
Verdict & Scientific Reason:

Flawless pairing of all 4 biomolecular classes with their characteristic covalent bonds.

💡
Why this is airtight: None. Standard first-principles biochemistry.
2 2
✗ Incorrect
Verdict & Scientific Reason:

Mismatches Protein with C=C double bonds and Unsaturated fatty acids with peptide bonds.

⚠️
Student Fallacy (Why candidates pick this trap): Inverting proteins and fatty acids.
3 3
✗ Incorrect
Verdict & Scientific Reason:

Mismatches Protein with phosphodiester bonds and Nucleic acid with peptide bonds.

⚠️
Student Fallacy (Why candidates pick this trap): Swapping proteins with nucleic acids.
4 4
✗ Incorrect
Verdict & Scientific Reason:

Mismatches Unsaturated fatty acid with glycosidic bonds and Nucleic acid with double bonds.

⚠️
Student Fallacy (Why candidates pick this trap): Confusing ester bonds with glycosidic bonds.
⚠️

NTA Trap Alert: Phosphodiester vs Glycosidic Bond Confusion

Students occasionally mix up nucleic acid backbone bonds (phosphodiester) with polysaccharide linkage bonds (glycosidic).

🛡️ How to avoid the -1 mark: Glycosidic = Sugar/carbohydrate (polysaccharide); Phosphodiester = Nucleic acid backbone.
📖

Core NEET Syllabus Standard

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

"In a polypeptide or a protein, amino acids are linked by a peptide bond. In a polysaccharide, monosaccharides are linked by glycosidic bond. In a nucleic acid, nucleotides are joined by phosphodiester bond. Unsaturated fatty acids have C=C double bonds."

Syllabus Focus: Nature of Bonds Linking Monomers in a Polymer
✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

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