Final answer:
PABA is used to synthesize folic acid and is essential for the growth of microorganisms that produce their own folic acid. It is not related to penicillin production, not a B-lactamase, nor similar to cephalosporins. Sulfa drugs inhibit bacterial growth by competing with PABA. Option 2 is correct.
Step-by-step explanation:
PABA, or para-aminobenzoic acid, is a compound that is essential in the synthesis of folic acid, which is a vitamin required by human beings and synthesized by microorganisms.
PABA serves as a precursor for the bacterial synthesis of folic acid, an essential factor for their growth. Sulfa drugs, which are structurally similar to PABA, act as competitive inhibitors by competing with PABA for the active site on the enzyme responsible for the synthesis of folic acid in bacteria.
This interference with folic acid production in pathogens is the basis of the antibacterial action of sulfa drugs. In contrast to sulfa drugs, PABA is not directly related to penicillin production, nor is it a type of B-lactamase enzyme, nor molecularly similar to cephalosporins.