Question

Fred Griffith studied two strains of Streptococcus pneumonia,one that causes a lethal infection when injected into mice, and a second that is harmless.He observed that pathogenic bacteria that have been killed by heating can no longer cause an infection. But when these heat-killed bacteria are mixed with live, harmless bacteria, this mixture is capable of infecting and killing a mouse. What did Griffith conclude from this experiment?

Answer 1

The correct answer will be- There is some molecule which could have transformed the avirulent bacterial strains to become virulent and called it a transforming principle.

Step-by-step explanation:

Griffith performed the experiment on two strains of Streptococcus pneumonia in which one strain is avirulent called R strain and another virulent strain called S strain.

When Griffith killed the S bacteria (virulent) by heat and added it in the R strain Petri dishes and then injected the bacteria to mice, the mice killed. This amazed him as to how the avirulent bacteria killed the mice ?

He concluded that there was some principle which transformed the avirulent bacteria to virulent bacteria and thus called the principle as transforming principle.