Final answer:
Carbon dioxide is transported in the blood mainly by dissolution in plasma, binding to hemoglobin, and as bicarbonate ions. 'As hydrogen ions' is not a way CO2 is transported, but rather a byproduct of CO2 conversion to bicarbonate.
Step-by-step explanation:
Carbon dioxide is transported in the human body by three primary mechanisms. The first method is dissolution in plasma, where carbon dioxide dissolves directly in the blood. Approximately 5 to 7 percent of all carbon dioxide is transported this way. The second method involves carbon dioxide binding to hemoglobin within red blood cells to form carbaminohemoglobin, accounting for about 10 percent of transported CO2. The third and most prevalent method is as bicarbonate ions (HCO3-), which is formed when carbon dioxide reacts with water in the presence of the enzyme carbonic anhydrase to form carbonic acid, which then dissociates into bicarbonate and hydrogen ions. This mechanism accounts for the majority of carbon dioxide transport.
The option "As hydrogen ions" is not a direct method of carbon dioxide transport. Instead, hydrogen ions are a byproduct of the conversion of carbon dioxide to bicarbonate within red blood cells. Therefore, the correct answer to the question 'Which of the following is not a way that carbon dioxide is transported in the body?' is 'As hydrogen ions'.