This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Structure and function of protein, Subject name: Biochemistry
[{'content': 'Alpha helix and Beta pleated sheet are examples of \nSelect and explain. \nA. Primary structure, B. Secondary structure, C. Teiary structure, D. Quaternary structure', 'role': 'user'}, {'content': "Answer: B \nExplanation: Regions of ordered secondary structure arise when a series of aminoacyl residues adopt similar phi and psi angles. Extended segments of polypeptide (example, loops) can possess a variety of such angles. The angles that define the two most common types of secondary structure, the ` helix and the a sheet, fall within the lower and upper left-hand quadrants of a Ramachandran plot, respectively. Ref: Harper's Illustrated Biochemistry, 30E (2015) pg no 38.", 'role': 'assistant'}]