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Biology Question 113 – NEET-UG 2023

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

The search for the genetic material involved several key experiments that progressively built evidence.

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Ninja Strategy•Direct Recall of Definitive Experiment

The question specifically asks for 'unequivocal proof,' which directly points to the Hershey-Chase experiment as the most conclusive demonstration of DNA as the genetic material.

Step 1: Recall Experiments on Genetic Material✦ Active

The question asks for the scientists who provided "unequivocal proof" that DNA is the genetic material. Several experiments contributed to this understanding over time.

Step 2: Evaluate Contributions of Each Option○ Expand

1. Frederick Griffith (1928): Demonstrated bacterial transformation but did not identify the transforming substance as DNA. 2. Avery, MacLeod, and McCarty (1944): Identified DNA as the transforming principle, providing strong evidence, but some scientists remained skeptical. 3. Alfred Hershey and Martha Chase (1952): Conducted experiments using bacteriophages and radioactive isotopes (32P for DNA and 35S for protein), which conclusively proved that DNA, not protein, is the genetic material. This is widely considered the "unequivocal proof." 4. Wilkins and Franklin: Provided X-ray diffraction data that was crucial for Watson and Crick to determine the structure of DNA, but their work did not directly prove DNA as the genetic material.

💡 Teacher's Secret Hint

Distinguish between experiments that suggested DNA's role and those that provided definitive proof.

Step 3: Identify the Unequivocal Proof○ Expand

Based on the evaluation, the Hershey-Chase experiment provided the most definitive and "unequivocal proof" that DNA is the genetic material.

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