Question

Approximately 70% of $C{O}_2$ is absorbed by the blood and will be transported to the lungs as ___________.

• A. bicarbonate ions
• B. carbamino haemoglobin
• C. gaseous form
• D. carbon monoxide

Answer 1

The correct option is A bicarbonate ions

Gases such as oxygen and carbon dioxide are transported by plasma and RBC. About 97% of the oxygen is transported by the RBC and the rest 3% is transported by plasma in dissolved state. Whereas 20% -25% of the $C{O}_2$ is transported by RBC, 7 % by plasma in dissolved state while 70% in the form of bicarbonate. RBC is a red blood cell which contains haemoglobin, an iron containing pigment. The respiratory gases, oxygen and carbon dioxide, bind to haemoglobin.
Oxygen binds to haemoglobin to form an unstable compound oxyhaemoglobin and with carbon dioxide to form carbaminohaemoglobin.