Q.131 Botany ⭐ 360° Option Elimination Active

Vault ↗

NEET 2023 Botany Question 131 Solution

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

Question

Unequivocal proof that DNA is the genetic material was first proposed by

✓

Verified Against NTA Final Answer Key

Option (3) : Alfred Hershey and Martha Chase

📚 Molecular Basis of Inheritance Easy

📋 Given Parameters & Problem Setup

Discovery Unequivocal proof of DNA as genetic material

Model System Bacteriophage T2 and Escherichia coli

Radioisotopes Used ³²P (DNA phosphate) and ³⁵S (Protein methionine/cysteine)

⚡

The 30-Second Exam Hall Shortcut: ⚡ Genetic Material Proof Hierarchy: Unequivocal = Hershey & Chase

⏱️ Save ~20 seconds

Griffith discovered transformation (1928), Avery-MacLeod-McCarty provided biochemical characterization (1944), but UNEQUIVOCAL proof was conclusively established by Alfred Hershey and Martha Chase in 1952 using radioactive isotopes ³²P and ³⁵S!

1 Griffith (1928): Transforming principle in Streptococcus pneumoniae (unproven chemical identity).

2 Avery, MacLeod, McCarty (1944): Biochemical evidence that DNA is transforming agent (not universally accepted by biologists).

3 Hershey and Chase (1952): Unequivocal proof using ³²P-DNA and ³⁵S-protein bacteriophage infection.

4 Match Option (3) Alfred Hershey and Martha Chase.

🛡️

Why You Can 100% Trust This Shortcut: Canonical NCERT Molecular Genetics historical milestone taxonomy.

📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Chronology of Genetic Material Evidence

The search for the genetic material followed three landmark historical stages:

\begin{aligned} \text{Griffith (1928):} & \quad \text{Transforming principle demonstrated in } \textit{S. pneumoniae} \\[3pt] \text{Avery et al. (1944):} & \quad \text{Biochemical proof that DNA is the transforming agent} \\[3pt] \text{\textbf{Hershey \& Chase (1952):}} & \quad \mathbf{\text{Unequivocal proof using radioactive } ^{32}\text{P and }^{35}\text{S in T2 phage}} \end{aligned}

Step 2

Verbatim NCERT Association

NCERT states verbatim: "The unequivocal proof that DNA is the genetic material came from the experiments of Alfred Hershey and Martha Chase (1952). They worked with viruses that infect bacteria called bacteriophages."

Step 3

Experimental Logic

Bacteria infected with viruses grown on radioactive phosphorus ( $^{32}\text{P}$ ) were radioactive because DNA entered the host cells. Bacteria infected with viruses grown on radioactive sulfur ( $^{35}\text{S}$ ) were not radioactive, confirming that protein did not enter bacteria.

⭐

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:

Maurice Wilkins and Rosalind Franklin produced X-ray diffraction photographs of DNA B-form fiber.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing X-ray crystallography with phage transduction experiments.

2 2

✗ Incorrect

Verdict & Scientific Reason:

Griffith observed bacterial transformation in mice but could not elucidate the chemical nature of the transforming agent.

⚠️

Student Fallacy (Why candidates pick this trap): Ignoring the qualifying descriptor "unequivocal proof".

3 3

✓ 100% Correct

Verdict & Scientific Reason:

Verbatim NCERT attribution: Hershey and Chase provided the unequivocal experimental proof that DNA is the genetic material in 1952.

💡

Why this is airtight: None; textbook verbatim.

4 4

✗ Incorrect

Verdict & Scientific Reason:

Avery, MacLeod, and McCarty discovered that DNA was the transforming substance, but their proof was debated until Hershey-Chase confirmed it unequivocally.

⚠️

Student Fallacy (Why candidates pick this trap): Overlooking that Avery et al.'s work was still contested by skeptics until Hershey-Chase.

⚠️

NTA Trap Alert: Avery et al. vs. Hershey & Chase "Unequivocal" Trap

Questions in NEET deliberately use the word "unequivocal" because NCERT reserves that exact adjective exclusively for Hershey and Chase.

🛡️ How to avoid the -1 mark: Keywords: "Biochemical characterisation of transforming principle" = Avery et al. "Unequivocal proof" = Hershey and Chase.

📖

Core NEET Syllabus Standard

NCERT Biology · Molecular Basis of Inheritance Standard Benchmark

Core Scientific Principle Tested:

"The unequivocal proof that DNA is the genetic material came from the experiments of Alfred Hershey and Martha Chase (1952)."

Syllabus Focus: The Genetic Material is DNA

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

Ready to attempt under real exam pressure?

Test your speed and accuracy in the authentic 200-minute timed NTA simulator.

Launch NEET 2023 CBT Test →

← Previous (Q.130) All Botany Questions Grid Next (Q.132) →

Spotted a mistake in this solution? Report an error ([email protected])

⚖️ Legal & Fair Dealing Notice: Sourced from publicly released NEET 2023 question papers and NEET answer keys for private study, research, and non-commercial educational practice under Fair Dealing (Section 52(1)(a) of the Indian Copyright Act, 1957). Not affiliated with or endorsed by NTA or NMC.

NEET 2023 Botany Question 131 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Genetic Material Proof Hierarchy: Unequivocal = Hershey & Chase

Step-by-Step Rigorous Workflow & Mathematical Proof

Chronology of Genetic Material Evidence

Verbatim NCERT Association

Experimental Logic

360° Option Elimination Engine Key Feature

NTA Trap Alert: Avery et al. vs. Hershey & Chase "Unequivocal" Trap

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

🔗 Related Questions — Molecular Basis of Inheritance

Lac Operon & Constitutive Expression of i-Gene

Eukaryotic RNA Polymerase II & hnRNA Synthesis

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

Salient Features of the Human Genome

Solve 4 NEET Questions a Day — One per Subject