Q.176 Zoology ⭐ 360° Option Elimination Active

NEET 2026 Zoology Question 176 Solution

Topic: Biotechnology: Principles and Processes · Official NTA Booklet Code 50

Question

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. Assertion A: In recombinant DNA technology, lysozyme is used for disrupting bacterial cells while cellulase is for plant cells. Reason R: Isolation of genetic material needs disruption of cells. In the light of the above statements, choose the most appropriate answer from the options given below:

(1)Both A and R are correct and R is the correct explanation of A
(2)Both A and R are correct but R is not the correct explanation of A
(3)A is correct but R is not correct
(4)A is not correct but R is correct

✓

Verified Against NTA Final Answer Key

Option (1) : Both (A) and (R) are true and (R) is the correct explanation of (A)

📚 Biotechnology: Principles and Processes Easy

📋 Given Parameters & Problem Setup

Assertion (A) For isolating DNA, bacterial cells are treated with lysozyme and plant cells are treated with cellulase.

Reason (R) Cell walls of bacteria and plants are composed of different chemical substances that require specific hydrolytic enzymes for cell lysis.

⚡

The 30-Second Exam Hall Shortcut: ⚡ Cell Wall Enzyme Specificity Rule

⏱️ Save ~35 seconds

Bacteria = Peptidoglycan (Lysozyme); Plants = Cellulose (Cellulase); Fungi = Chitin (Chitinase)!

1 Read Assertion (A): Lysozyme for bacteria, cellulase for plants -> TRUE (NCERT verbatim).

2 Read Reason (R): Bacterial and plant cell walls have different chemical compositions requiring specific enzymes -> TRUE (bacteria = peptidoglycan, plant = cellulose).

3 Apply "BECAUSE": Different enzymes are used BECAUSE bacterial walls are peptidoglycan (cleaved by lysozyme) while plant walls are cellulose (cleaved by cellulase). Enzymes are substrate-specific.

4 Reason (R) provides the exact biochemical explanation for Assertion (A).

5 Select Option (1).

🛡️

Why You Can 100% Trust This Shortcut: NCERT Biology · Biotechnology: Principles and Processes (Polymerase Chain Reaction: Thermostable Taq polymerase from Thermus aquaticus).

📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Principle of Cell Lysis for DNA Isolation

To isolate pure DNA, the cell envelope must be broken open to release DNA along with other macromolecules. Since bacterial, plant, and fungal cells possess rigid cell walls of distinct chemical nature, specific hydrolytic enzymes are required.

\begin{aligned} \text{Bacterial Cell Wall (Peptidoglycan)} &\xrightarrow{\text{Lysozyme}} \text{Lysis} \\ \text{Plant Cell Wall (Cellulose)} &\xrightarrow{\text{Cellulase}} \text{Lysis} \\ \text{Fungal Cell Wall (Chitin)} &\xrightarrow{\text{Chitinase}} \text{Lysis} \end{aligned}

• Assertion (A) is completely true.

Step 2

Enzyme Specificity and Explanatory Link

Lysozyme specifically hydrolyzes the β(1→4) glycosidic bonds between NAM and NAG in peptidoglycan, but cannot hydrolyze cellulose. Conversely, cellulase specifically cleaves β(1→4) glucan bonds in plant cellulose. Thus, Reason (R) is true and is the exact biochemical explanation for Assertion (A).

\text{Different Wall Chemistry} \implies \text{Substrate-Specific Hydrolytic Enzymes} \implies (R) \text{ explains } (A)

• Subsequent treatment with ribonuclease removes RNA, and protease removes proteins, before ice-cold ethanol precipitates purified DNA.

⭐

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:

100% correct. Reason (R) directly explains why distinct enzymes (lysozyme vs. cellulase) must be used for bacteria and plants.

💡

Why this is airtight: None; textbook biochemistry.

2 B

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. The different chemical nature of cell walls is the precise reason different enzymes are required.

⚠️

Student Fallacy (Why candidates pick this trap): Failing to connect enzyme specificity with cell wall composition.

3 C

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Reason (R) is an undisputed biological fact.

⚠️

Student Fallacy (Why candidates pick this trap): Assuming plant and bacterial walls have identical composition.

4 D

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Assertion (A) is the standard protocol for DNA extraction.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing the enzymes used for DNA isolation.

⚠️

NTA Trap Alert: Enzyme-Organism Pairing Trap

Remember the complete NCERT triad for DNA extraction: Bacteria -> Lysozyme; Plant -> Cellulase; Fungus -> Chitinase.

🛡️ How to avoid the -1 mark: Match the root word: Cellulose -> Cellulase; Chitin -> Chitinase; Peptidoglycan -> Lysozyme.

📖

Core NEET Syllabus Standard

NEET Biology Core Syllabus · Biotechnology: Principles and Processes Standard Benchmark

Core Scientific Principle Tested:

"Bacterial cells are treated with lysozyme, plant cells with cellulase, and fungus with chitinase to degrade specific cell wall components."

Syllabus Focus: Isolation of the Genetic Material (DNA)

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

Bacteria-Lysozyme, Plant-Cellulase, Fungus-Chitinase: Match the Wall to the Axe!

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NEET 2026 Zoology Question 176 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Cell Wall Enzyme Specificity Rule

Step-by-Step Rigorous Workflow & Mathematical Proof

Principle of Cell Lysis for DNA Isolation

Enzyme Specificity and Explanatory Link

360° Option Elimination Engine Key Feature

NTA Trap Alert: Enzyme-Organism Pairing Trap

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

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