The antibiotic resistance gene of a plasmid vector is used in the selection of which of the following when foreign $DNA$ is inserted?

In the $PCR$ technique,the amplification of a $DNA$ segment is carried out by which enzyme?

What should a cloning vector $NOT$ possess?

Given below are two statements:
Statement $I$: Plasmids are autonomously replicating $DNA$.
Statement $II$: Plasmids are extrachromosomal $DNA$.
In the light of the above statements, choose the correct answer from the options given below:

Match the column-$I$ with column-$II$ with respect to the nomenclature of enzyme $Eco RI$ and select the correct answer from the codes given below.

Column-$I$	Column-$II$
$(A) E$	$(1) 1^{st}$ in order of identification
$(B) co$	$(2)$ Name of genus
$(C) R$	$(3)$ Name of species
$(D) I$	$(4)$ Name of strain

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