Hugo de Vries studied mutations in

$...$ 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.

Mutations are ........

Mutations are generally induced by which of the following?

Mutations are usually induced by

$A$ 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......