Agarose,extracted from seaweeds,is used in:

Which gene is not present in normal $E. coli$ cells?

$A$ : $Pst I$ generates single-stranded overhanging stretches in $DNA$ after digestion that facilitate ligation.
$R$ : These short extensions can form hydrogen bonds with their complementary counterparts,which are then sealed by $DNA$ ligase to form phosphodiester bonds.

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.

Which restriction enzyme produces blunt ends upon cleavage?

$Taq$ polymerase is isolated from a bacterium,$Thermus$ $aquaticus$.