The correct answer is Option (4) -(A), (C), (B), (D)

In 1928, Frederick Griffith, in a series of experiments with Streptococcus pneumoniae (bacterium responsible for pneumonia), witnessed a miraculous transformation in the bacteria. During the course of hisexperiment, a living organism (bacteria) had changed in physical form.

When Streptococcus pneumoniae (pneumococcus) bacteria 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.

 

S strain → injected into mice → Mice die

R strain → injected into mice → Mice live

 

 

Griffith was able to kill bacteria by heating them. He observed that heat-killed S strain bacteria injected into mice did not kill them. When he injected a mixture of heat-killed S and live R bacteria, the mice died.Moreover, he recovered living S bacteria from the dead mice.

 

S' strain (Heat killed) → injected into mice → Mice live

'S' strain (Heat killed) + 'R' Strain (Live) → injected into mice → Mice die