<prompt> The key factor in the transpo of carbon dioxide as bicarbonate isThe high solubility of CO2 in H20The presence of Hb in bloodThe presence of carbonic anhydrase in the erythrocytesThe acid nature of carbon dioxide and the alkaline nature of bicarbonate  <response>: Since the Pco2 in the tissue is high,CO2 diffuses from tissues into the plasma. From there it enters the RBC which contains plenty of carbonic anhydrase. In blood,70 of CO2 is transpoed as HCO3 by the action of carbonic anhydrase. Reference:Textbook of medical physiology-Geetha N,2nd edition,page no:245. 