........ make cuts at specific positions within the $DNA$.

The organism, which is used for gene transfer in higher plants is

Restriction enzyme was discovered by

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:

$DNA$ carries a ..... charge,so it moves towards the ......... electrode.

Identify the vectors for animals and plants respectively.