AS-Level Biology question!!!Watch
CO2 will diffuse from the tissue-->tissue fluid-->plasma-->RBC. CO2 with react with water producing H2CO3 using the enzyme "carbonic anhydrase". H2CO3 will then break down into H+ and HCO3-. H+ will then combine with Hb so it doesn't increase the acidity in the cell, and "some" of the HCO3- will diffuse out of the cell. When inhaling O2, it will enter the RBC and bind to Hb releasing the H+ which will return back to the cell and react with the remaining HCO3- producing H2CO3 ( because this is a reversible rxn) which will then be broken down again by using carbonic anhydrase into H2O and CO2. CO2 will then diffuse out of the cell to be exhaled.