To introduce recombinant $DNA$ into a host cell,it is first kept on ice,then placed at ........ temperature,and finally placed back on ice. (in $^{\circ} C$)

Consider the following statements:
$I.$ In microinjection method,foreign $DNA$ is directly injected into the nucleus of an animal cell or plant cell by using microneedles or micropipettes.
$II.$ Microinjection method is used in oocytes,eggs,and embryos.
$III.$ Electroporation is the formation of temporary pores in the plasma membrane of a host cell by using lysozyme or calcium chloride.
$IV.$ In chemical-mediated gene transfer method,certain chemicals such as $CO_{2}$ help foreign $DNA$ to enter the host cell.
Which of the statements given above are correct?

If a recombinant $DNA$ bearing a gene for resistance to Ampicillin is transferred into $E. coli$ cells,the host cells become transformed into Ampicillin-resistant cells. What happens when these $E. coli$ are grown on a medium containing Ampicillin?

$A$ simple stirred-tank bioreactor is shown below. Identify $A, B, C, D$,and $E$.

In this process,$DNA$ fragments are transferred from the gel to a synthetic membrane.

Identify the given figure.