Rapid antigen test and $RT$-$PCR$ are two diagnostic tests for the $COVID-19$ virus. $PCR$,a molecular diagnostic tool,stands for:

Which of the following is used for direct gene transfer?

Diagrammatically represent the experimental steps in cloning and expressing a human gene (e.g.,the gene for growth hormone) in a bacterium like $E. coli$.

Study the given figure carefully and select the correct statements regarding this.
$I.$ It represents typical agarose gel electrophoresis showing differential migration of $DNA$ fragments.
$II.$ Lane $1$ contains undigested $DNA$ fragments.
$III.$ Lanes $2$ to $4$ contain digested $DNA$ fragments.
$IV.$ Smallest $DNA$ bands are present at $(A)$ position and largest $DNA$ bands are present at $(B)$ position.

When a foreign $DNA$ is introduced into an organism,how is it maintained in the host and how is it transferred to the progeny of the organism?

Significance of heat shock method in bacterial transformation is to facilitate