Avery, Macleoid and McCarty gave the biochemical characterisation of Transforming Principle.
The transformation experiments by using Pneumococcus was conducted by Frederick Griffith. Wilkins and Franklin produced $X$-ray diffraction data of $DNA.$
$i.$ Glucose or galactose may bind with the repressor and inactivate it.
$ii.$ In the absence of lactose, the repressor binds with the operator region.
$iii.$ The z-gene codes for permease.
$iv.$ This was elucidated by Francois Jacob and Jacque Monod.