Select the appropriate option for $RNAi$.

$I.$ In the process of recombinant $DNA$ technology,after several treatments,the purified $DNA$ is precipitated by adding chilled ethanol.
$II.$ The bacterial,plant,or animal cell is broken down by enzymes to release $DNA$,along with $RNA$,proteins,polysaccharides,and lipids.
Choose the correct option for the above statements.

Which of the following methods is not commonly used for introducing foreign $DNA$ into the plant cell?

$I.$ $DNA$ being a hydrophilic molecule cannot pass through cell membranes.
$II.$ The bacteria should be made competent to accept the $DNA$ molecule.
The correct option regarding the above statements is:

In a stirred-tank bioreactor,the stirrer facilitates $........$

What is the process of cutting out the $DNA$ bands from the agarose gel and extracting them from the gel piece called?