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
Threonine is metabolised to: 
Select and explain. 
A. Lysine, B. Arginine, C. Ornithine, D. Glycine
D: Glycine
Answer: D: Glycine 
Explanation: Threonine aldolase cleaves threonine to acetaldehyde and glycine. Oxidation of acetaldehyde to acetate is followed by formation of acetyl-CoA. Ref: Harper 28th edition, chapter 29.