Mutations which alter nucleotide sequence within a gene are called

Study the given figure of a nucleosome and select the option that correctly identifies the parts $A, B$ and $C$.

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

Which one of the following is wrongly matched?

The structural formula of the pentose sugar present in $DNA$ is given. Select the correct group for the position marked '$X$' from the options.

Given below are two statements.
Statement $I$: Heterocatalytic function of $DNA$ includes transcription and translation.
Statement $II$: $A$ unique feature of $DNA$ molecule which helps in its semiconservative duplication is the complementary nature of two strands.
In the light of the above statements,choose the correct answer from the options given below.