Q.157 Zoology ⭐ 360° Option Elimination Active

NEET 2023 Zoology Question 157 Solution

Topic: Molecular Basis of Inheritance · Official NTA Booklet Code G5

Question

Given below are two statements: Statement I: RNA mutates at a faster rate. Statement II: Viruses having RNA genome and shorter life span mutate and evolve faster. In the light of the above statements, choose the correct answer from the options given below:

(1)Statement I false but Statement II is true.
(2)Both Statement I and Statement II are true.
(3)Both Statement I and Statement II are false.
(4)Statement I is true but Statement II is false.

✓

Verified Against NTA Final Answer Key

Option (2) : Both Statement I and Statement II are true.

📚 Molecular Basis of Inheritance Easy

📋 Given Parameters & Problem Setup

Statement I RNA mutates at a faster rate.

Statement II Viruses having RNA genome and shorter life span mutate and evolve faster.

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The 30-Second Exam Hall Shortcut: ⚡ 2′-OH Labile Bond = Fast RNA Viral Evolution

⏱️ Save ~20 seconds

RNA has a reactive 2′-OH group making it labile and prone to high mutation rates (Statement I is TRUE). Consequently, RNA viruses with short generation times mutate and evolve rapidly (Statement II is TRUE). Both statements are TRUE!

1 Check Statement I: RNA is chemically reactive (2′-OH) and mutates at a faster rate than DNA -> True.

2 Check Statement II: RNA viruses with short life spans mutate and evolve faster -> Verbatim NCERT, True.

3 Both Statement I and Statement II are true.

4 Match Option (2).

🛡️

Why You Can 100% Trust This Shortcut: Canonical NCERT Molecular Genetics nucleic acid stability and viral mutation dynamics.

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Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Chemical Basis of RNA Instability

RNA possesses a 2′-hydroxyl group on each ribose sugar ring, making the phosphodiester backbone catalytic and chemically labile, while uracil is less stable than thymine:

\text{Ribose 2'-OH} + \text{Uracil} \implies \text{Higher chemical reactivity} \implies \mathbf{\text{RNA mutates at a faster rate}}

Step 2

Verbatim NCERT Reference

NCERT states verbatim under "RNA World / Properties of Genetic Material": - "RNA being unstable, mutates at a faster rate." - "Consequently, viruses having RNA genome and having shorter life span mutate and evolve faster."

Step 3

Evolutionary Corroboration

Examples include influenza virus, HIV, and SARS-CoV-2, whose error-prone RNA-dependent RNA polymerases lack 3′ to 5′ proofreading, leading to rapid antigenic drift and antigenic shifts.

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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

✗ Incorrect

Verdict & Scientific Reason:

Statement I is factually true: RNA mutates faster than DNA.

⚠️

Student Fallacy (Why candidates pick this trap): Assuming DNA and RNA mutate at identical baseline rates.

2 2

✓ 100% Correct

Verdict & Scientific Reason:

Both statements are verbatim excerpts from NCERT Molecular Basis of Inheritance.

💡

Why this is airtight: None; textbook verbatim recall.

3 3

✗ Incorrect

Verdict & Scientific Reason:

Both statements are scientifically established biological facts.

⚠️

Student Fallacy (Why candidates pick this trap): Skeptical rejection of viral evolution kinetics.

4 4

✗ Incorrect

Verdict & Scientific Reason:

Statement II is factually true: RNA viruses evolve exceptionally rapidly.

⚠️

Student Fallacy (Why candidates pick this trap): Believing shorter lifespan retards the rate of evolution.

⚠️

NTA Trap Alert: DNA Stability vs. RNA Evolution Trap

DNA was selected over evolutionary time for stability of genetic storage (double-stranded, thymine instead of uracil, no 2′-OH). RNA is dynamic and prone to mutations, allowing rapid viral evolution.

🛡️ How to avoid the -1 mark: Remember: DNA = Stable storage. RNA = Unstable, mutates and evolves faster.

📖

Core NEET Syllabus Standard

NCERT Biology · Molecular Basis of Inheritance Standard Benchmark

Core Scientific Principle Tested:

"RNA being unstable, mutates at a faster rate. Consequently, viruses having RNA genome and having shorter life span mutate and evolve faster."

Syllabus Focus: Properties of Genetic Material (DNA vs. RNA)

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

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NEET 2023 Zoology Question 157 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ 2′-OH Labile Bond = Fast RNA Viral Evolution

Step-by-Step Rigorous Workflow & Mathematical Proof

Chemical Basis of RNA Instability

Verbatim NCERT Reference

Evolutionary Corroboration

360° Option Elimination Engine Key Feature

NTA Trap Alert: DNA Stability vs. RNA Evolution Trap

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

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