Which of the following is a suitable vector for gene cloning in higher organisms?

$A$ plasmid $DNA$ and a linear $DNA$ (both are of the same size) have one site for a restriction endonuclease. When cut and separated on agarose gel electrophoresis,the plasmid shows one $DNA$ band while the linear $DNA$ shows two fragments. Explain.

Identify the antibiotic resistance gene from the following options.

Match the following columns:

Column-$I$	Column-$II$
$(a) \ Cla \ I$	$(1) \ \text{Antibiotic resistance gene}$
$(b) \ pBR322$	$(2) \ \text{Origin of replication}$
$(c) \ tet^R$	$(3) \ \text{Restriction enzyme}$
$(d) \ ori$	$(4) \ \text{Plasmid}$

Which of the following has the ability to replicate independently within a bacterial cell?

Eco-$RI$ cuts the $DNA$ between . . . . . . only when the sequence $GAATTC$ is present in the $DNA$.