Amino acids exhibit amphoteric behavior because they contain both acidic and basic functional groups. The amino group (\( -NH_2 \)) can function as a base by accepting protons, while the carboxyl group (\( -COOH \)) can donate protons, acting as an acid. This dual functionality allows amino acids to behave as both acids and bases, depending on the pH of the solution, illustrating their amphoteric nature.
\bigskip