Which of the following is important in genetic engineering?

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 $EcoRI$,the letter $R$ stands for:

Select the correct pair from the following:

Vehicle $DNA$ in rDNA technology is the common name given to . . . . . . .

What are plasmids? Describe their role in bacteria.