CUET Preparation Today
| Read the the given statements and answer the questions that follow :- When Streptococcus pneumoniae bacteria were grown on a culture plate some produced smooth shiny colonies and others produced rough colony. Mice infected with the S strain died from pneumonia infection but mice infected with the R strain didn't develop pneumonia. When Griffith heat killed the S strain bacteria and injected it into the mice, the mice did not die .While on the other hand when he injected S strain heat killed bacteria with live R strain into the mice ,they died. |
| Why did the mice die on adding of heat killed S strain with live R strain? |
Transduction of R strain bacteria.
Transformation of R strain bacteria by heat killed S strain bacteria.
Transformation of R strain bacteria by S strain bacteria .
Transformation of S strain bacteria by R strain bacteria.
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| Transformation of R strain bacteria by heat killed S strain bacteria. |
| Griffith 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. |
