The digestion of which macromolecule is not stimulated by the action of peptidases?

• A. Proteins
• B. Carbohydrates
• C. Nucleic acids
• D. Lipids

Answer: (D)

Peptidases are enzymes specifically involved in the breakdown of proteins into smaller peptides and amino acids. They function by hydrolyzing the peptide bonds that link amino acids together in protein structures. Given this role, it follows that the digestion of proteins is directly stimulated by peptidases.

Carbohydrates, nucleic acids, and lipids are different macromolecules with distinct enzyme classes that facilitate their digestion. For example, carbohydrates are primarily broken down by amylases and other carbohydrate-specific enzymes, while nucleic acids are digested by nucleases that target the bonds in nucleotides. Lipids, on the other hand, are mainly digested by lipases that break down triglycerides into fatty acids and glycerol.

Since peptidases specifically target protein substrates, the digestion of macromolecules like carbohydrates, nucleic acids, and lipids does not involve peptidases, making lipids the correct choice for a macromolecule whose digestion is not influenced by these enzymes. This focuses on the specificity of enzymatic action in digestion processes across different types of macromolecules.