Which one of the following statements is not correct about a plasmid?

Give any two microbes that are useful in biotechnology.

What type of ends are produced when $DNA$ is cut by $EcoR\, I$?

Which enzyme is required to prevent unwanted self-ligation of vector $DNA$ molecules in recombinant $DNA$ technology?

In bacteria,genes for antibiotic resistance are usually located in:

Refer to the following statements for agarose-gel electrophoresis :
$(a)$ Agarose is a natural polymer obtained from sea-weed.
$(b)$ The separation of $DNA$ molecules in agarose-gel electrophoresis depends on the size of $DNA$.
$(c)$ The $DNA$ migrates from negatively-charged electrode to the positively-charged electrode.
$(d)$ The $DNA$ migrates from positively-charged electrode to the negatively-charged electrode.
Choose the most appropriate answer from the options given below :