Separated $DNA$ fragments on an agarose gel can be visualized after staining with ....

During the process of gene amplification using $PCR$,if very high temperature is not maintained in the beginning,then which of the following steps of $PCR$ will be affected first?

$I.$ $DNA$ being a hydrophilic molecule cannot pass through cell membranes.
$II.$ The bacteria should be made competent to accept the $DNA$ molecule.
The correct option regarding the above statements is:

Why are stirred-tank bioreactors specifically designed?

Which one of the following statements is wrong with respect to separation of $DNA$ fragments on gel electrophoresis?

Which of the following is correct for polymerase chain reaction $(\text{PCR})$?