Which of the following incorrectly describes mechanisms of CO2 transport? O just over 20% of CO2 is carried in the form of carbaminohemoglobin attached to the heme part of hemoglobin as bicarbonate ions in plasma 7-10% of CO2 is dissolved directly into the plasma all of the above Question 66 (1 point) The beginning of a true capillary is surrounded by a precapillary sphincter. The opening and closing of precapillary sphincters is controlled by blood pressure in the metarteriole O local chemical conditions sympathetic nervous system parasympathetic nervous system Question 67 (1 point) Which of the following is true regarding normal quiet expiration of air? It is driven by increased blood CO2 levels. It is a passive process that depends on the recoil of elastic fibers that were stretched during inspiration. It depends on the complete lack of surface tension on the alveolar wall. It requires contraction of abdominal wall muscles.