What does $Y$ represent in the given figure?

Match the enzyme in Column $I$ with its role in Column $II$:

Column $I$	Column $II$
$1$. Ligase	$a$. Peptide bond formation
$2$. Ribozyme	$b$. Hydrolysis of lactose
$3$. Permease	$c$. Joining of Okazaki fragments
$4$. $\beta$-galactosidase	$d$. Increases permeability

Choose the correct answer from the following options.

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

Genetic mapping of bacteriophage $\phi X174$ has been done by

The figure shows an important concept of $DNA$ implication. Fill in the blanks from $A$ to $C$.

Read the following statements and select the correct statements:
$(A)$ Essential life processes such as metabolism,translation and splicing are evolved around $\text{RNA.}$
$(B)$ Heavy isotope of nitrogen $(^{15}N)$ is a radioactive isotope,while light isotope of nitrogen $(^{14}N)$ is not a radioactive isotope.
$(C)$ The codon in $\text{rRNA}$ is read in a contiguous fashion.
$(D)$ In the first phase of translation,amino acids are activated in the presence of $\text{ATP.}$
$(E)$ $\text{DNA}$ from every tissue from an individual shows a high degree of polymorphism.
Choose the correct answer from the options given below: