Question

Major amount of carbon dioxide is transported by blood in the form of

• A. bicarbonates
• B. carbonic acid
• C. carbamino-haemoglobin
• D. carboxy-haemoglobin

Answer 1

The correct option is A bicarbonates

Carbon dioxide formed during cellular respiration in all the tissues of the body reaches lungs through blood in three ways.
1. As carbonic acid: Very less amount of carbon dioxide is transported by blood as carbonic acid as it alters the pH of blood.
2. As carbamino-haemoglobin: Carbon dioxide combines with haemoglobin to form carbamino-haemoglobin. Only 20-25% of CO${}_2$ is transported in this manner.
3. As bicarbonates: Around 70% of carbon dioxide is transported by blood as bicarbonates.

Carboxyhaemoglobin is formed when CO combines with haemoglobin and it is very harmful for the organism.