Which of the following was responsible for the transformation of $R$ cells into $S$ cells?

Zinder and Lederberg demonstrated the process of transduction in which of the following bacteria?

Who proved for the first time that $DNA$ is the genetic material?

Analyze the following experimental steps performed by Frederick Griffith:
$I - R$ strain $\rightarrow$ injected into mice
$II - S$ strain $\rightarrow$ injected into mice
$III - S$ strain (heat-killed) $\rightarrow$ injected into mice
$IV - S$ strain (heat-killed) $+ R$ strain (live) $\rightarrow$ injected into mice
In which of the above stages will the mice remain alive?

Who among the following scientists developed the cytochemical technique for the detection of $DNA$?

Transformation in bacteria was discovered by