How does carbonic acid work to maintain blood pH? (Select all that apply.) Check All That Apply When blood is too basic, carbonic acid can ionize to bicarbonate and H+ ions, adding H+ ions to the blood. When blood is too basic, carbonic acid can ionize to bicarbonate and H+ ions, adding H+ ions to the blood. When blood becomes too acidic, bicarbonate combines with extra H+ ions to form carbonic acid, removing H+ ions from the blood. When blood becomes too acidic, bicarbonate combines with extra H+ ions to form carbonic acid, removing H+ ions from the blood. Carbonic acid is added to the blood until the pH reaches 7.4. Carbonic acid is added to the blood until the pH reaches 7.4. Carbonic acid always lowers the blood pH to 7.4. Carbonic acid always lowers the blood pH to 7.4. Carbonic acid can raise or lower the pH of blood. Carbonic acid can raise or lower the pH of blood.