Crown gall disease in plants is caused by

Which restriction enzymes have recognition sites within the antibiotic resistance genes $amp^R$ and $tet^R$ in the plasmid $pBR322$?

Differentiate between Restriction Endonuclease and Restriction Exonuclease.

While isolating $DNA$ from bacteria,which of the following enzymes is not used?

Restriction enzymes that are used in the construction of recombinant $DNA$ are endonucleases which cut the $DNA$ at 'specific-recognition sequence'. What would be the disadvantage if they do not cut the $DNA$ at specific-recognition sequence?

Nowadays, which of the following are known as "magic circles"?