Assertion :In Griffiths experiment, a mixture of heat-killed virulent bacteria R and live non-virulent bacteria 5, lead to the death of mice. Reason: Transforming principle got transferred from heat-killed R strain to S strain and made it virulent.

Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

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Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

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Assertion is correct but Reason is incorrect

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Both Assertion and Reason are incorrect

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Solution

The correct option is D Both Assertion and Reason are incorrect
When bacteria Streptococcus pneumoniae are grown on a culture plate, some produce smooth shiny colonies (S) while others produce rough colonies (R). This is because the S strain bacteria have a mucous (polysaccharide) coat, while R strain does not. Mice infected with the S strain (virulent) die from pneumonia infection but mice infected with the R strain do not develop pneumonia. In Griffiths experiment, some transforming principle, transferred from the heat-killed S strain, had enabled the R strain to synthesize a smooth polysaccharide coat and become virulent which must be due to the transfer of the genetic material. This is known as transformation.
So, the correct answer is 'Both Assertion and Reason are incorrect'.

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