A β-sheet, along with an α-helix, refers to secondary protein structure.
a) primary structure
b) secondary structure
c) tertiary structure
d) quaternary structure
a) primary structure, incorrect, Primary structure refers to the sequence of amino acids.
b) secondary structure, correct.
c) tertiary structure, incorrect, Tertiary structure refers to the combination of secondary structures. The tertiary structure often results from interactions of side chains within a protein structure.
d) quaternary structure, incorrect, Quaternary structure refers to organization of tertiary structures.