Which one of the following gases in the blood causes oxygen deficiency during smoking?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Carbon monoxide
(1) Nitrogen oxide — Incorrect. It is not the gas that lowers the oxygen carried by haemoglobin in a smoker.
(2) Carbon dioxide — Incorrect. Carbon dioxide is a waste gas of respiration. The blood carries it to the lungs. It is not the cause of oxygen shortage in smoking.
(3) Oxygen — Incorrect. Oxygen is the gas that falls short. It is not the gas that causes the shortage.
(4) Carbon monoxide — Correct. Smoking raises the carbon monoxide (CO) content of the blood. CO takes the place of oxygen on haemoglobin, so the haem-bound oxygen falls. This causes oxygen deficiency in the body.
NCERT Extract:
Drugs and Alcohol Abuse – “… Smoking is associated with increased incidence of cancers of lung, urinary bladder and throat, bronchitis, emphysema, coronary heart disease, gastric ulcer, etc. Tobacco chewing is associated with increased risk of cancer of the oral cavity. Smoking increases carbon monoxide (CO) content in blood and reduces the concentration of haembound oxygen. This causes oxygen deficiency in the body.”