This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: vitamins, Subject name: Biochemistry
Conversion of glycine to serine requires 
Select and explain. 
A. Folic acid, B. Thiamine, C. Vit. C, D. Fe2+
A: Folic acid
Answer: A: Folic acid 
Explanation: Conversion of glycine to serine require folic acid. From serine, The beta carbon of serine is channelled into the one-carbon pool, carried by THFA (tetrahydro folic acid). The alpha carbon of serine becomes the alpha carbon of glycine. Serine is the most impoant source of One-Carbon units Serine Hydroxy Methyl Transferase is the enzyme involved in this pathway. Ref: DM Vasudevan - Textbook of Biochemistry, 8th edition, page no: 475