<prompt> The main site of bicarbonate re-absorption is:Proximal convoluted tubuleDistal convoluted tubuleCoical collecting ductMedullary collecting duct  <response>: Proximal convoluted tubule is the main site of bicarbonate absorption. About 80 to 90 percent of bicarbonate re-absorption occurs in the proximal tubule. Ref:Textbook of Medical Physiology By Guyton, 10th Edition, Page 353 