Which organism is used as a vector to introduce specific genes into host plants?

In $EcoR\, I$,what do the letters $E$ and $R$ stand for,respectively?

$BACs$ and $YACs$ are . . . . . . .

Match the columns:

Column-$I$	Column-$II$
$(a)$ Ligase	$(i)$ It removes nucleotides from $DNA$ ends.
$(b)$ Endonuclease	$(ii)$ Connects parts of $DNA$.
$(c)$ Exonuclease	$(iii)$ Removes phosphates from $DNA$.
$(d)$ $DNA$ Polymerase	$(iv)$ It produces sticky ends in $DNA$.
	$(v)$ Useful for repeated amplification.

$A$ - Restriction endonucleases are also called 'molecular scissors'.
$R$ - When fragments generated by restriction endonucleases are mixed,they join together due to their sticky ends.

Select the option that excludes characteristics applicable to plasmids:
$(a)$. Circular $DNA$
$(b)$. Linear $DNA$
$(c)$. Present in all bacteria
$(d)$. Contain essential genes
$(e)$. Extra chromosomal self-replicating