Select the appropriate option for $Agrobacterium$ $tumefaciens$.

In the naming of restriction enzymes, the first letter is derived from $...A...$ name, the next two letters from the $...B...$, and the fourth letter from $...C...$ of $...D...$ where the enzymes are extracted.
$A$ to $D$ in the statement can be:

Assertion : Plasmids are extrachromosomal $DNA$.
Reason : Plasmids are found in bacteria and are useful in genetic engineering.

In transformation,microparticles are bombarded with the help of a gene gun,which are made of ............ .

Name the five key tools for accomplishing the tasks of recombinant $DNA$ technology. Also mention the functions of each tool.

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