The scientist who discovered the mutagenic nature of $X$-rays and ultraviolet $(UV)$ radiation is......

$...$ is a phenomenon by which genetic variation is achieved through changes in the base sequences within genes,which creates a new character or trait absent in the parental generation.

Which base is responsible for spontaneous point mutations?

What is the cause of mutation?

The most important example of point mutation is found in a disease called

Normally $DNA$ molecule has $A-T$ and $G-C$ pairing. However,these bases can exist in alternative valency status,owing to rearrangements called: