Which of the following is required for the amplification of a gene of interest by $PCR$?

What is meant by gene cloning?

Given below are four statements pertaining to the separation of $DNA$ fragments using gel electrophoresis. Identify the incorrect statements:
$(a)$ $DNA$ is a negatively charged molecule and so it is loaded on the gel towards the Anode terminal.
$(b)$ $DNA$ fragments travel along the surface of the gel,whose concentration does not affect the movement of $DNA$.
$(c)$ The smaller the size of the $DNA$ fragment,the larger is the distance it travels through it.
$(d)$ Pure $DNA$ can be visualized directly by exposing it to $UV$ radiation.
Choose the correct answer from the options given below:

$A$ mixture of fragmented $DNA$ was electrophoresed in an agarose gel. After staining the gel with ethidium bromide,no $DNA$ bands were observed. What could be the reason?

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.

Given below are two statements.
Statement $I$ - The isolated $DNA$ of donor organism is cleaved by suitable restriction endonuclease to form $DNA$ fragments with cohesive staggered or blunt ends.
Statement $II$ - The foreign $DNA$ or passenger $DNA$ can also be obtained directly from genomic or cDNA library.
In the light of above statements,select the correct option given below: