This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: TCA Cycle, Subject name: Biochemistry
[{'content': '2 carbon atoms which leave in the form of CO2 in TCA, are derived from: \nSelect and explain. \nA. Acetyl CoA, B. Oxaloacetate, C. CO2, D. Citrate', 'role': 'user'}, {'content': "Answer: B \nExplanation: 2 molecules of CO2 which are lost in TCA, are from Oxaloacetate. Acetyl CoA in one turn of the cycle gives it's carbons to oxaloacetate, not CO2. In the 2nd turn of the cycle , these two carbons from Oxaloacetate will be lost in the form of CO2. Answer oxaloacetate >>Acetyl CoA.", 'role': 'assistant'}]