This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Amino Acid Metabolism, Subject name: Biochemistry
Tyrosine is synthesized from- 
Select and explain. 
A. Tryptophan, B. Phenylalanine, C. Histidine, D. Methionine
B: Phenylalanine
Answer: B: Phenylalanine 
Explanation: Ans. is 'b' i.e., Phenylalanine o Phenylalanine metabolism is initiated by its oxidation to tyrosine which then undergoes oxidative degradation.