Select the correct option to make a bacterial cell competent to take up $DNA$.

In the presence of a chromogenic substrate,recombinant bacteria appear as .......

What is required for the expression of a foreign gene?

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?

What happens if a foreign $DNA$ fragment is inserted into the coding sequence of the $\beta$-galactosidase enzyme in a plasmid containing the coding sequence for the $\beta$-galactosidase enzyme?

From the given combination of steps in $PCR$,identify the enzyme-dependent step.