This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nucleotides, Subject name: Biochemistry
[{'content': 'Which one of the following is the major site for Purine nucleotide biosynthesis? \nSelect and explain. \nA. Liver, B. Erythrocytes, C. Polymorphonuclear leukocytes, D. Brain', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Liver is the major site for Purine nucleotide biosynthesis. Erythrocytes, Polymorphonuclear leukocytes and Brain cannot produce purines. The purines are built upon a pre-existing ribose 5-phosphate.', 'role': 'assistant'}]