The enzyme restriction endonuclease:

$A$ special sequence from where $DNA$ replication starts.

Which of the following statements are not true regarding restriction endonucleases?
$A$. They are called molecular scissors.
$B$. These are the enzymes responsible for restricting the growth of bacteriophages in $E. coli$.
$C$. They cut the $DNA$ only at the centre of the palindromic sites.
$D$. They remove nucleotides only from the ends of $DNA$ fragments.
$E$. They recognise specific palindromic base-pair sequences.
Choose the answer from the options given below:

In gel electrophoresis, the separated $DNA$ fragments can be visualized only after staining the $DNA$ with a compound known as ............. followed by exposure to $UV$ radiation.

Which organism is most commonly used as a host in $r-DNA$ technology?

$A$ plasmid: