Q.167 Zoology ⭐ 360° Option Elimination Active

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NEET 2026 Zoology Question 167 Solution

Topic: Molecular Basis of Inheritance · Official NTA Booklet Code 50

Question

Which of the following enzymes synthesizes precursor mRNA?

(1)RNA polymerase I
(2)RNA polymerase II
(3)RNA polymerase II
(4)DNA polymerase

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Verified Against NTA Final Answer Key

Option (2) : RNA polymerase II

📚 Molecular Basis of Inheritance Easy

📋 Given Parameters & Problem Setup

Cell Type Eukaryote

Target Transcript Precursor of mRNA (Heterogeneous nuclear RNA / hnRNA)

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The 30-Second Exam Hall Shortcut: ⚡ 1-2-3 / R-M-T Eukaryotic RNA Pol Formula

⏱️ Save ~40 seconds

Pol I = rRNA; Pol II = mRNA (hnRNA); Pol III = tRNA (5S rRNA, snRNA)!

1 Use the universal mnemonic: "1-r, 2-m, 3-t" (Ready Made Transcripts).

2 RNA Polymerase I -> transcribes rRNAs (28S, 18S, and 5.8S).

3 RNA Polymerase II -> transcribes hnRNA (precursor of mRNA).

4 RNA Polymerase III -> transcribes tRNA, 5S rRNA, and snRNAs.

5 The question asks for precursor of mRNA (hnRNA) -> RNA Polymerase II.

6 Pick Option (2) in under 10 seconds!

🛡️

Why You Can 100% Trust This Shortcut: NCERT Biology · Molecular Basis of Inheritance (Central Dogma & Genetic Code: AUG codes for Methionine and acts as initiator).

📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Division of Labour Among Eukaryotic RNA Polymerases

In eukaryotes, there are at least three RNA polymerases in the nucleus (in addition to the RNA polymerase found in the organelles). There is a clear division of labour among them.

\begin{aligned} \text{RNA Pol I} &\rightarrow 28\text{S}, 18\text{S}, 5.8\text{S rRNA} \\ \mathbf{\text{RNA Pol II}} &\rightarrow \mathbf{\text{hnRNA (precursor of mRNA)}} \\ \text{RNA Pol III} &\rightarrow \text{tRNA}, 5\text{S rRNA}, \text{snRNAs} \end{aligned}

• Eukaryotic RNA polymerase II also synthesizes microRNAs (miRNAs).

Step 2

Processing of hnRNA into Mature mRNA

The primary transcript (hnRNA) synthesized by RNA polymerase II contains both exons (coding) and introns (non-coding). It undergoes post-transcriptional processing: 5' capping with methylguanosine triphosphate, splicing out of introns by spliceosomes, and 3' polyadenylation (tailing).

\text{hnRNA} \xrightarrow{\text{Capping + Splicing + Tailing}} \text{Mature mRNA}

• DNA polymerases synthesize DNA, not RNA.

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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 A

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. RNA polymerase I transcribes ribosomal RNAs (28S, 18S, and 5.8S), not hnRNA.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing RNA Pol I with RNA Pol II.

2 B

✓ 100% Correct

Verdict & Scientific Reason:

100% correct. RNA polymerase II specifically transcribes the precursor of mRNA, namely heterogeneous nuclear RNA (hnRNA).

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Why this is airtight: None; fundamental molecular genetics rule.

3 C

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. RNA polymerase III is responsible for transcription of tRNA, 5S rRNA, and snRNAs (small nuclear RNAs).

⚠️

Student Fallacy (Why candidates pick this trap): Confusing Pol III targets with Pol II.

4 D

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. DNA polymerase II is a prokaryotic DNA-dependent DNA polymerase involved in DNA repair, not an RNA polymerase.

⚠️

Student Fallacy (Why candidates pick this trap): Conflating DNA polymerase with RNA polymerase.

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NTA Trap Alert: 5S rRNA Exception Trap

Students often generalize "all rRNA is made by Pol I". 28S, 18S, and 5.8S are made by Pol I, but 5S rRNA is transcribed by RNA Polymerase III.

🛡️ How to avoid the -1 mark: Use R-M-T mnemonic: 1 = Ribosomal (except 5S), 2 = Messenger (hnRNA), 3 = Transfer (plus 5S & snRNA).

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Core NEET Syllabus Standard

NEET Biology Core Syllabus · Molecular Basis of Inheritance Standard Benchmark

Core Scientific Principle Tested:

"RNA polymerase II transcribes precursor of mRNA, the heterogeneous nuclear RNA (hnRNA)."

Syllabus Focus: Transcription in Eukaryotes

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

1-R, 2-M, 3-T: Polymerase Two Makes Messenger (hnRNA)!

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Post-Transcriptional Processing of Eukaryotic hnRNA (Splicing, Capping, Tailing)

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NEET 2026 Zoology Question 167 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ 1-2-3 / R-M-T Eukaryotic RNA Pol Formula

Step-by-Step Rigorous Workflow & Mathematical Proof

Division of Labour Among Eukaryotic RNA Polymerases

Processing of hnRNA into Mature mRNA

360° Option Elimination Engine Key Feature

NTA Trap Alert: 5S rRNA Exception Trap

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

🔗 Related Questions — Molecular Basis of Inheritance

RNA as the First Genetic Material & Evolution of Stable Double-Helical DNA

Salient Features of the Human Genome

RNA Interactions during Translation and RNA Interference (RNAi)

Post-Transcriptional Processing of Eukaryotic hnRNA (Splicing, Capping, Tailing)

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