- A Bicarbonate ions
- B Carbonic acid crystals
- C Dissolved gas in plasma
- D Carbaminohemoglobin
Correct answer: A. Bicarbonate ions
Explanation: About 70% of CO2 is transported as bicarbonate ions (HCO3-) formed in RBCs with the help of carbonic anhydrase; a smaller fraction binds hemoglobin as carbaminohemoglobin.
Concept context
The mechanics of breathing, lung volumes, gas transport in blood, the Bohr effect, and respiratory regulation.