Identify the antibiotic resistance gene from the following options.

$A$ : $Pst I$ 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.

In $pBR322$,which of the following codes for the proteins involved in the replication of the plasmid?

Which of the following is a cloning vector?

Discuss with your teacher and find out how to distinguish between (Any two):
$(a)$ Plasmid $DNA$ and Chromosomal $DNA$
$(b)$ $RNA$ and $DNA$
$(c)$ Exonuclease and Endonuclease

What is the small, circular $DNA$ molecule present in bacterial cells in addition to the main genomic $DNA$ called?