$GAATTC$ is the recognition site for the restriction endonuclease:

$A$ single-stranded nucleic acid tagged with a radioactive molecule is called a .............. .

Match the following enzymes with their functions:

$(a)$ Restriction endonuclease	$(i)$ Joins the $DNA$ fragments
$(b)$ Restriction exonuclease	$(ii)$ Extends primers on genomic $DNA$ template
$(c)$ $DNA$ ligase	$(iii)$ Cuts $DNA$ at specific positions
$(d)$ $Taq$ polymerase	$(iv)$ Removes nucleotides from the ends of $DNA$

Select the correct option from the following:

Which of the following is not used for isolation of $\text{DNA}$ from cells?

What is the source organism for $\text{EcoRI}$,a restriction endonuclease?

The key tools required for the recombinant $DNA$ technology are:
$I.$ Restriction enzymes
$II.$ Polymerase enzymes
$III.$ Ligases
$IV.$ Vectors
$V.$ Host organisms
Select the correct option.