Who discovered the mutagenic effect of $X$-rays?

The classical example of point mutation is

Which phenomenon leads to the variation in $DNA$?

Haploids are more useful than diploids for the study of mutations because...

$A$ mutant microorganism is unable to synthesize a component required for its growth,but it is able to grow if that component is provided. This is called a/an......

Replacement of which one of the following nucleotides in the $Hb^A$ gene causes sickle cell anaemia?