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

Bacteria were grown in a medium containing a heavy isotope of nitrogen $(^{15}N)$ for many generations,and all their $DNA$ contained only heavy nitrogen. $A$ bacterium of this type was transferred to a normal medium and allowed to duplicate. After two divisions,the distribution of heavy $DNA$ is likely to be:

$A$ completely radioactive double-stranded $DNA$ molecule undergoes two rounds of replication in a non-radioactive medium. What will be the radioactive status of the four daughter molecules?

$DNA$ repairing is done by

$E. coli$ has only $4.6 \times 10^{6}$ base pairs and completes the process of replication within $18$ minutes; then the average rate of polymerisation is approximately

Which of the following statements is correct about $DNA$ polymerase?