Answer:
Human cells can readily absorb folic acid; bacteria cells cannot.
Explanation:
Bacterial cells cannot absorb folic acid and synthesize it. On the other hand, humans do not synthesize folic acid in their cells. They rather obtain it from the diet. Sulfa drugs, for example, sulfanilamide resemble p-aminobenzoate (PABA). PABA is a molecule that is used as a substrate in the synthesis of the coenzyme folic acid. The sulfa drugs serve as competitive inhibitors and compete with PABA for the catalytic site of an enzyme involved in the folic acid synthesis. This prevents the synthesis of folic acid in bacterial cells and thereby, inhibits bacterial growth.