DNA as Hereditary Material — NEET Biology

Correct answer: A — S2, S3 and S5 only

Let's evaluate each statement regarding Avery, MacLeod, and McCarty's experiment: * **S1: They concluded that DNA is the hereditary material.** This statement is correct. They discovered that DNA alone from S bacteria caused R bacteria to become transformed, leading to this conclusion. (Page 85, Para 2) * **S2: Protease treatment of the heat-killed S strain extract prevented transformation.** This statement is incorrect. They discovered that protein-digesting enzymes (proteases) did *not* affect transformation, meaning the transforming substance was not a protein. (Page 85, Para 2) * **S3: RNase treatment destroyed the transforming ability of the S strain extract.** This statement is incorrect. They found that RNA-digesting enzymes (RNases) did *not* affect transformation, indicating the transforming substance was not RNA. (Page 85, Para 2) * **S4: Their experiment built directly upon the findings of Frederick Griffith.** This statement is correct. They worked to determine the biochemical nature of the 'transforming principle' discovered by Griffith. (Page 85, Para 1) * **S5: The initial belief among biologists was that RNA served as the genetic material.** This statement is incorrect. Prior to their work, the genetic material was generally thought to be a protein. (Page 85, Para 1) Therefore, statements S2, S3, and S5 are NOT correct.