$RNA$ is removed by the treatment with

Which one of the following statements is wrong with respect to separation of $DNA$ fragments on gel electrophoresis?

Choose the correct statement:
$P -$ Endonucleases cut the $DNA$ at a specific site inside the $DNA$.
$Q -$ $A$ stirred-tank reactor is usually square in shape.
$R -$ In order to force bacteria to take up the plasmid,the bacterial cells must first be made 'competent' to take up $DNA$ by treating them with a divalent cation like $Ca^{2+}$.

Separation and purification by filtration,centrifugation of the desired compound produced in a bioreactor is a part of:

Polymerase chain reaction $\text{(PCR)}$ amplifies $\text{DNA}$ following the equation:

In which method are host cells bombarded with high-velocity micro-particles of gold or tungsten coated with $DNA$?