Carbon dioxide in the blood is carried most efficiently by
A) bicarbonate ions
B) being dissolved in blood plasma
C) combining with hemoglobin in blood cells
D) moving up the diffusion gradient of carbon dioxide in the tissues

Question

Quizplus · Accepted Answer

Carbon dioxide is most efficiently carried in the blood in the form of bicarbonate ions, which are formed when carbon dioxide combines with water in the blood, with the help of an enzyme called carbonic anhydrase. Bicarbonate ions are then transported in the blood plasma. While carbon dioxide can also dissolve in the blood plasma, the majority of it is carried as bicarbonate ions. Carbon dioxide does not bind to hemoglobin in the same way that oxygen does, and while it can diffuse in and out of tissues, this is a slower and less efficient method of transport compared to bicarbonate ions.

Carbon Dioxide in the Blood Is Carried Most Efficiently by