The point mutations $A$ to $G$,$C$ to $T$,$C$ to $G$,and $T$ to $A$ in $DNA$ are:

In Lederberg's replica plating experiment,what should be used to obtain streptomycin-resistant strains?

Match Column-$I$ with Column-$II$:

Column-$I$	Column-$II$
$(a)$ Lactose	$(i)$ Functional part of the gene
$(b)$ Release factor	$(ii)$ Inducer of $Lac$ operon
$(c)$ Histone	$(iii)$ Packaging of $\text{DNA}$
$(d)$ Exon	$(iv)$ Termination of translation

Read the following four statements ($1$ to $4$):
$1$. In transcription,uracil pairs with adenosine.
$2$. Regulation of $lac$ operon by a repressor is referred to as positive regulation.
$3$. The human genome contains approximately $50,000$ genes.
$4$. Haemophilia is a sex-linked recessive disease.
How many of the above statements are correct?

Assertion $(A):$ The split gene arrangement represents probably an ancient feature of the genome.
Reason $(R):$ $\text{hnRNA}$ undergoes additional processing called as capping and tailing.
Choose the correct option.

The life span of $mRNA$ in $E. coli$ is: