This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of protein and amino acid, Subject name: Biochemistry
Glucogenic amino acid are all except 
Select and explain. 
A. Valine, B. Alanine, C. Tryptophan, D. Methionine
C: Tryptophan
Answer: C: Tryptophan 
Explanation: Tryptophan is both glucogenic &ketogenic. Others are purely glucogenicRef: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 27