Biotechnology is the modern branch of biology which deals with

Assertion : In recombinant $DNA$ technology,human genes are often transferred into bacteria (prokaryotes) or yeast (eukaryote).
Reason : Both bacteria and yeast multiply very fast to form huge population,which express the desired gene.

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A):$
Polymerase chain reaction is used in $DNA$ amplification.
Reason $(R):$
The ampicillin resistant gene is used as a selectable marker to check transformation.
In the light of the above statements,choose the correct answer from the options given below:

Assertion $:-$ The tumor inducing $(Ti)$ plasmid of $Agrobacterium$ $tumefaciens$ has now been modified into a cloning vector.
Reason $:-$ Retroviruses have been disarmed and are now used to deliver genes into animal cells.

Which of the following statements is not true?
$I.$ $DNA$, being a hydrophilic molecule, cannot pass through cell membranes.
$II.$ $Agrobacterium$ $tumefaciens$ delivers a piece of $DNA$ known as $'T-DNA'$ in the $Ti$ plasmid, which transforms normal plant cells into tumour cells to produce chemicals against pathogens.
$III.$ Retrovirus, adenovirus, and papillomavirus are also now used as cloning vectors in animals because of their ability to transform normal cells into cancerous cells.
$IV.$ In genetic engineering, $DNA$ from different sources are cut with the same restriction enzymes so that both $DNA$ fragments have the same kind of sticky ends.
Choose the correct option.

Give differences between $PCR$ and plasmid.