The presence of a chromogenic substrate gives ............ coloured colonies.

What is the charge on $DNA$ and towards which electrode does it migrate during gel electrophoresis?

$I. ... A...$ is the ability of a cell to take up foreign $DNA$.
$II.$ The cell is treated with a specific concentration of a divalent cation such as $... B...$ to increase the pore size in the cell wall.
$III.$ In $...C...$ method,recombinant $DNA$ is directly injected into the nucleus of an animal cell.
The most appropriate option regarding $A, B$ and $C$ is:

Assertion : The uptake of $DNA$ during transformation is an active,energy-requiring process.
Reason : Transformation occurs in only those bacteria,which possess the enzymatic machinery involved in the active uptake and recombination.

The correct order of steps in Polymerase Chain Reaction $(PCR)$ is

What is the criterion for the movement of $DNA$ fragments on an agarose gel during gel electrophoresis?