Which of the following is not a method of introducing alien $DNA$ into host cells?

$I.$ 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.

How many types of primers are required for the amplification of a gene in $PCR$?

$A$ number of bacteria with recombinant $DNA$ of the same type form:

Significance of treating bacterial cells with calcium chloride before transformation is to facilitate

Which chemical is utilised during the isolation of $DNA$ at the end of precipitation?