This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
[{'content': 'The hormonal factor responsible for circadian rhythm is formed from which amino acid? \nSelect and explain. \nA. Tyrosine, B. Tryptophan, C. Phenylalanine, D. Histidine', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Tryptophan In circadian rhythm maintenance melatonin is involved which is derived from tryptophan.Tryptophan is a precursor for synthesis of niacin (nicotinic acid), serotonin and melatonin.", 'role': 'assistant'}]