Question

Regarding the assertion and reason, select the right option.
Assertion [A]: Cigarette smoke contains CO which leads to difficulty in breathing.
Reason [R]: CO is a poisonous gas that reduces the amount of haeme-bound oxygen, so less oxygen is available in the bloodstream.

• A. Both A and R are true and R explains A
• B. Both A and R are true R does not explain A
• C. A is true and R is false
• D. Both A and R are false

Answer 1

The correct option is A Both A and R are true and R explains A

Cigarette smoke contains carbon monoxide. Everyone has a small amount of CO in blood. Smokers usually have more than three times as much as non-smokers. RBCs carry oxygen to all the parts of the body as oxygen is bound to haemoglobin. CO has more affinity for haemoglobin than oxygen. When CO enters the bloodstream, it binds to haeme and prevents oxygen from doing so. CO is then circulated in blood instead of oxygen preventing the brain, heart and other body parts from receiving oxygen they need.