This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Renal Tubular Reabsorption and Secretion, Subject name: Physiology
[{'content': 'Site of maximum bicarbonate absorption- \nSelect and explain. \nA. Proximal convoluted tubule, B. Distal convoluted tubule, C. Cortical collecting duct, D. Medullary collecting duct', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Proximal convoluted tubule o About 80-90 of filtered HCO3- is absorbed in PCT.o Absorption of HCO3- is indirect, which is due to secretion H+, i.e., secretion of H+ is coupled with absorption of HCO3o Filtered HCO3- reacts with H+ to form H2CO3 which then is dissociated into H2O and CO2.o CO2 diffuses into epithelial cell and generate HCO3- which is then reabsorbed.", 'role': 'assistant'}]