How is the majority of carbon dioxide carried in the blood?Multiple choice question.In the cytoplasm of red blood cellsAs CO2 dissolved in the plasmaAs bicarbonate ion in the blood plasmaCombined with hemoglobin

The majority of carbon dioxide is carried in the blood as bicarbonate ion in the blood plasma. Here's a step-by-step explanation:

1. Carbon dioxide (CO2) is produced as a waste product in cells during the process of cellular respiration.

2. This CO2 diffuses out of the cells and into the capillaries, where it enters the blood.

3. In the blood, a small amount of CO2 (about 7%) dissolves directly into the plasma. However, this is not the primary method of CO2 transport.

4. The majority of CO2 (about 70%) reacts with water in the blood to form carbonic acid (H2CO3), a reaction that is catalyzed by the enzyme carbonic anhydrase, which is found in red blood cells.

5. The carbonic acid quickly dissociates into a bicarbonate ion (HCO3-) and a hydrogen ion (H+). The bicarbonate ion is the form in which CO2 is carried in the blood to the lungs.

6. The remaining CO2 (about 23%) binds to hemoglobin in red blood cells and is carried to the lungs in this form.

So, the majority of CO2 is carried in the blood as bicarbonate ion in the blood plasma.