The smallest unit of genetic material which,when altered,results in a mutation is known as .....

$A$ mutant micro-organism unable to synthesize a compound required for its growth but able to grow if the compound is provided,is known as

The $T_4$ bacteriophage $rII$ mutant strain fails to lyse $E. coli$. However,when two strains $rII^X$ and $rII^Y$ are mixed,they lyse $E. coli$. What is the possible reason for this?

Which one of the following pairs is not correctly matched?

Chemically,$DNA$ differs from $RNA$ in having:

What does $Y$ represent in the given figure?