Griffith's Transformation Experiment — NEET Biology
📚 Practice ConceptHe concluded that the R strain bacteria had somehow been transformed by the heat-killed S strain bacteria. Some 'transforming principle', transferred from the heat-killed S strain, had enabled the R strain to synthesise a smooth polysaccharide coat and become virulent. This must be due to the transfer of the genetic material. However, the biochemical nature of genetic material was not defined from his experiments.
Which of the following statements are NOT correct concerning Frederick Griffith's experiment and its subsequent biochemical characterization? S1. Griffith's experiment clearly demonstrated that a 'transforming principle' was transferred from heat-killed S strain to live R strain bacteria. S2. The R strain bacteria, upon transformation, lost their ability to synthesize a smooth polysaccharide coat. S3. The main limitation of Griffith's experiment was its inability to identify the specific chemical nature of the genetic material. S4. Avery, MacLeod, and McCarty utilized protein-digesting enzymes (proteases) which inhibited transformation. S5. The transforming principle in Griffith's experiment was found to be stable enough not to be destroyed by heat. S6. Griffith's findings directly contradicted Mendel's principles of inheritance.
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Correct answer: B — S2, S4 and S6 only
Griffith's experiment was a foundational step in understanding genetic material. Let's evaluate each statement: S1. He concluded that the R strain bacteria had somehow been transformed by the heat-killed S strain bacteria. Some 'transforming principle' was transferred. This statement is correct. S2. The R strain, upon transformation, was enabled to synthesise a smooth polysaccharide coat and become virulent. It did not lose this ability. Thus, this statement is NOT correct. S3. However, the biochemical nature of genetic material was not defined from his experiments. This statement is correct. S4. Protein-digesting enzymes (proteases) and RNA-digesting enzymes (RNases) did not affect transformation, meaning they did not inhibit it. Thus, this statement is NOT correct. S5. Stability as one of the properties of genetic material was very evident in Griffith’s ‘transforming principle’ itself that heat, which killed the bacteria, at least did not destroy some of the properties of genetic material. This statement is correct. S6. Griffith's findings demonstrated transformation, which laid the groundwork for identifying genetic material, and did not contradict Mendel's principles but rather sought to understand the molecular basis of inheritance. Thus, this statement is NOT correct. Therefore, statements S2, S4, and S6 are NOT correct.
What does NCERT say about He concluded that R?
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