Who discovered $PCR$ (Polymerase Chain Reaction)?

Which of the following is added to precipitate purified $DNA$?

Which of the following is the correct sequence of steps in the Polymerase Chain Reaction $(PCR)$?

The $Polyethylene \ Glycol$ $(PEG)$ method is useful for which of the following?

With respect to $DNA$ fragmentation:
Statement $A$: Gel electrophoresis and elution are two important processes.
Statement $B$: After staining with ethidium bromide,it has to be exposed to $UV$ light.

Following enzymes/chemical/technique are used in the process of gel electrophoresis:
$I.$ sample $DNA$ is cut into fragments
$II.$ restriction endonucleases
$III.$ agarose gel
$IV.$ ethidium bromide
$V.$ $UV$-radiation
$VI.$ elution
Mark the correct sequence of their use.