Q.Explain how oxygen deficiency is caused by carbon monoxide in our blood? Give its effect.

Step 1. Carbon monoxide is released mainly by automobile exhaust from incomplete combustion and is inhaled into the lungs along with the air we breathe.

Step 2. In the bloodstream, CO binds with haemoglobin -- the protein in red blood cells that normally carries oxygen -- to form carboxyhaemoglobin.

Step 3. Haemoglobin locked up as carboxyhaemoglobin can no longer bind and transport oxygen, so this impairs the normal oxygen transport by blood; the overall effect is that the oxygen-carrying capacity of blood is reduced, even though the person is still breathing normal air. …

Explain the mechanism as a chain: CO inhaled -> binds haemoglobin -> carboxyhaemoglobin cannot carry O₂ -> reduced O₂-carrying c …

• Saying CO 'poisons' the blood without explaining the actual haemoglobin-binding mechanism, or confusing it with CO₂ (which is normally transported …