[Campbell Biology P.997] Which of the following is the primary form in which carbon dioxide ... | Practice Question

Which of the following is the primary form in which carbon dioxide is transported in the blood, according to the provided text?

  • A: As dissolved CO2 in blood plasma.
  • B: Bound to hemoglobin as carbaminohemoglobin.
  • C: As bicarbonate ions (HCO3-) in the blood plasma.
  • D: As carbonic acid (H2CO3) in the erythrocytes.

Explanation

The text states that CO2 diffuses into erythrocytes and reacts with water to form H2CO3, which readily dissociates into H+ and HCO3-. It then specifies that 'Most HCO3- diffuses out of the erythrocytes and is transported to the lungs in the plasma.' While some CO2 is transported as dissolved CO2 7% and bound to hemoglobin 5% , the largest proportion is transported as bicarbonate ions in the plasma.