The two bacteria found to be very useful in genetic engineering experiments are .............. .

Which of the following statements does not hold true for restriction enzymes?

Nowadays, which of the following are known as "magic circles"?

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A)$: When a particular restriction enzyme cuts a strand of $DNA$,overhanging stretches or sticky ends are formed.
Reason $(R)$: Some restriction enzymes cut the strand of $DNA$ a little away from the centre of the palindromic site.
In the light of the above statements,choose the correct answer from the options given below:

What does $R$ represent in $EcoR\, I$?

Which one of the following statements is not correct about a plasmid?