Who proposed the Mutation Theory?

Mutations can be artificially induced by which of the following?

Point mutation may occur due to

Non-ionizing radiations are generally known to cause mutations in organisms. These are:

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

What is a change in the nucleotide sequence of $DNA$ called?