Which two antibiotic resistance genes are present on the pBR322 vector?

Ampicillin and tetracycline

The correct answer is Option (3) Ampicillin and tetracycline.

Explanation:

• The pBR322 vector contains two antibiotic resistance genes: ampicillin resistance (amp^R) and tetracycline resistance (tet^R).
• These genes are used as selectable markers in gene cloning. When foreign DNA is inserted into one of these genes (e.g., the tetracycline resistance gene), the vector loses resistance to that specific antibiotic (tetracycline) while still maintaining resistance to ampicillin.
• This allows scientists to easily distinguish between recombinant plasmids (which lose tetracycline resistance) and non-recombinant ones (which retain both resistances).

The other options are incorrect because pBR322 does not contain genes for resistance to chloramphenicol or kanamycin