Segment of $DNA$ which is responsible for inheritance and expression of a particular character is known as

Explain the role of the following scientists:
$1.$ Avery, MacLeod, and McCarty $(1933-44)$
$2.$ Matthew Meselson and Franklin Stahl $(1958)$

Given below are two statements:
Statement $I$: Transfer $\text{RNAs}$ and ribosomal $\text{RNA}$ do not interact with $\text{mRNA}$.
Statement $II$: $\text{RNA}$ interference $\text{(RNAi)}$ takes place in all eukaryotic organisms as a method of cellular defence.
In the light of the above statements,choose the most appropriate answer from the options given below.

$A$ $DNA$ strand is directly involved in the synthesis of the following,except:

Genetic mutations occur in which of the following?

In which process is nucleic acid synthesized from nucleic acid?