Q.145 Botany ⭐ 360° Option Elimination Active

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NEET 2021 Botany Question 145 Solution

Topic: Molecular Basis of Inheritance · Official NTA Booklet Code M1

Question

What is the role of RNA polymerase III in the process of transcription in eukaryotes?

(1)Transcribes rRNAs (28S, 18S and 5.8S)
(2)Transcribes tRNA, 5s rRNA and snRNA
(3)Transcribes precursor of mRNA
(4)Transcribes only snRNAs

✓

Verified Against NTA Final Answer Key

Option (2) : Transcribes tRNA, 5s rRNA and snRNA

📚 Molecular Basis of Inheritance Easy

📋 Given Parameters & Problem Setup

Enzyme RNA polymerase III in eukaryotes

Target RNA transcripts synthesized by this specific enzyme

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The 30-Second Exam Hall Shortcut: ⚡ Eukaryotic RNA Polymerase Division: I $\to$ rRNA, II $\to$ mRNA, III $\to$ tRNA + 5S + snRNA

⏱️ Save ~15 seconds

NCERT defines the strict tripartite division of labor in eukaryotic nuclei: RNA Pol I transcribes 28S, 18S, and 5.8S rRNA; RNA Pol II transcribes hnRNA (precursor of mRNA); RNA Pol III transcribes tRNA, 5S rRNA, and snRNAs! RNA Pol III corresponds to Option (2)!

1 RNA Polymerase I: Transcribes rRNAs (28S, 18S, and 5.8S).

2 RNA Polymerase II: Transcribes precursor of mRNA (heterogeneous nuclear RNA, hnRNA).

3 RNA Polymerase III: Transcribes tRNA, 5S rRNA, and snRNA (small nuclear RNAs).

4 Match Option (2).

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Why You Can 100% Trust This Shortcut: Canonical NCERT Molecular Basis of Inheritance on Eukaryotic RNA Polymerases.

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Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Eukaryotic Nuclear RNA Polymerase Specialization

Unlike bacteria where a single RNA polymerase transcribes all RNAs, eukaryotic nuclei contain three distinct RNA polymerases showing complete division of labor:

\begin{aligned} \text{\textbf{RNA Polymerase I:}} & \quad \text{Transcribes rRNAs } (28\text{S}, 18\text{S}, 5.8\text{S}) \\[4pt] \text{\textbf{RNA Polymerase II:}} & \quad \text{Transcribes precursor of mRNA } (hn\text{RNA}) \\[4pt] \mathbf{\text{RNA Polymerase III:}} & \quad \mathbf{\text{Transcribes tRNA, 5S rRNA, and snRNAs (small nuclear RNAs)}} \end{aligned}

Step 2

Option Alignment

Question asks for the specific role of RNA polymerase III. Option (2) explicitly lists "tRNA, 5s rRNA and snRNA", which is identical to the canonical NCERT text.

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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:

This is the specific function of RNA polymerase I, not RNA polymerase III.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing RNA Polymerase I with RNA Polymerase III.

2 2

✓ 100% Correct

Verdict & Scientific Reason:

This is the precise, canonical role of eukaryotic RNA polymerase III.

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Why this is airtight: None. Direct textbook fact.

3 3

✗ Incorrect

Verdict & Scientific Reason:

Precursor of mRNA (hnRNA) is transcribed by RNA polymerase II.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing RNA Polymerase II with RNA Polymerase III.

4 4

✗ Incorrect

Verdict & Scientific Reason:

RNA polymerase III also transcribes tRNA and 5S rRNA, not "only" snRNAs.

⚠️

Student Fallacy (Why candidates pick this trap): Falling for the restrictive "only" qualifier.

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NTA Trap Alert: 5S rRNA Exception Trap

Notice that 28S, 18S, and 5.8S rRNAs are transcribed by Pol I, but the 5S rRNA is transcribed by Pol III! NTA frequently tests this exact exception.

🛡️ How to avoid the -1 mark: Mnemonic: "Pol I makes big rRNAs; Pol II makes mRNA; Pol III makes small RNAs (tRNA, 5S rRNA, snRNA)".

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Core NEET Syllabus Standard

NEET / NCERT Biology · Molecular Basis of Inheritance Standard Benchmark

Core Scientific Principle Tested:

"In eukaryotes, there are three RNA polymerases. RNA polymerase I transcribes rRNAs (28S, 18S, and 5.8S); RNA polymerase III transcribes tRNA, 5srRNA, and snRNAs; RNA polymerase II transcribes hnRNA."

Syllabus Focus: Transcription: Process of Transcription in Eukaryotes

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

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NEET 2021 Botany Question 145 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Eukaryotic RNA Polymerase Division: I →\to→ rRNA, II →\to→ mRNA, III →\to→ tRNA + 5S + snRNA

Step-by-Step Rigorous Workflow & Mathematical Proof

Eukaryotic Nuclear RNA Polymerase Specialization

Option Alignment

360° Option Elimination Engine Key Feature

NTA Trap Alert: 5S rRNA Exception Trap

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

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The 30-Second Exam Hall Shortcut: ⚡ Eukaryotic RNA Polymerase Division: I $\to$ rRNA, II $\to$ mRNA, III $\to$ tRNA + 5S + snRNA