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

The separated bands of $DNA$ are cut out from the agarose gel and extracted from the gel piece. This step is known as . . . . . . .

In which method are host cells bombarded with high-velocity micro-particles of gold or tungsten coated with $DNA$?

Downstream processing includes:
$I.$ Separation of the product from the reactor
$II.$ Purification of the product
$III.$ Formulation of the product with suitable preservatives
$IV.$ Quality control testing and clinical trials in case of drugs
Which of the statements given above are correct?

Which of the following statements is incorrect?

Which statements are correct for gel electrophoresis to separate $\text{DNA}$ fragments?
$(a)$ $\text{DNA}$ is a negatively charged molecule and so it is loaded on the gel towards the anode terminal.
$(b)$ $\text{DNA}$ fragments travel along the surface of the gel whose concentration does not affect the movement of $\text{DNA}$.
$(c)$ Smaller the size of $\text{DNA}$ fragments,larger is the distance it travels through it.
$(d)$ Pure $\text{DNA}$ can be visualized directly by exposing it to $\text{UV}$ radiation.