Which of the following serves a dual purpose in $DNA$ replication?

Primase is a type of ...........

Identify the given model.

An $E. coli$ cell with light $DNA$ is incubated in a culture medium containing a heavy isotope of nitrogen $(^{15}N)$. After $60$ minutes, find out the percentage of light $DNA$. (in $\%$)

During the replication of a bacterial chromosome,$DNA$ synthesis starts from the origin of replication and proceeds in a.....

During $DNA$ replication, the term leading template is applied to the one which replicates itself in $A$ and the replication is $B$.