Alpha helix and Beta pleated sheets are examples of which of the following protein structure:

Alpha helix and Beta pleated sheets are secondary structure of protein. The two most common types of secondary structure, the alpha helix and the beta sheet. Secondary structure is produced from folding or coiling of the peptide chain (primary structure) and production of cross linkages or bonds, mainly the Hydrogen bonds. Ref: Harper's Biochemistry, 26th Edition, Page 31 ; Chatterjee Shinde, 5th Edition, Page 82 ; General, Organic and Biological Chemistry By H. Stephen Stoker, 2012, Page 730