What functional group is folic acid part of, and use the chemical structure to explain why?

Answer 1

Folic acid is a carboxylic acid, actually having two -COOH groups present in the molecule. There are many other functional groups present in the molecule as well, including an amide group, -C{=O}NH-, a pteridine group (fused benzene rings with 4 nitrogens in the structure) with amino and hydroxy substituents, etc.