Question

what type of bonds stabilize the secondary structure of proteins? hydrogen bonds ionic bonds covalent bonds van der waals forces

Explanation:

Proteins have four levels of structure. The secondary structure (like alpha - helices and beta - sheets) is stabilized by hydrogen bonds. Ionic bonds are more involved in tertiary or quaternary structures (influenced by charge interactions). Covalent bonds (such as peptide bonds) are for the primary structure (linking amino acids). Van der Waals forces also play a role in tertiary and quaternary structures (weak intermolecular forces).

Answer:

Hydrogen bonds