$DNA$ repairing is done by

In which type of $DNA$ replication,out of the two newly formed molecules,one is purely new and the other is entirely old?

If $E. coli$ is allowed to grow for $40$ minutes in a medium containing $^{15}N$,then the number of $^{14}N / ^{14}N$ containing $DNA$ molecules would be:

$A$ bacterium containing fully radioactive $DNA$ is allowed to replicate in a non-radioactive medium for two generations. What percentage of bacteria should contain radioactive $DNA$ (in $\%$)?

$DNA$ replication requires:

Choose the correct statement about the direction of $DNA$ strand.