2010 General Studies, all questions

UPSC Prelims 2010 · General Studies

Question 126: Science and Technology

Excessive release of the pollutant carbon monoxide (CO) into the air may produce a condition in which oxygen supply in the human body decreases. What causes this condition ?

aWhen inhaled into the human body, CO is converted into CO₂
bThe inhaled CO has much higher affinity for haemoglobin as compared to oxygen
cThe inhaled CO destroys the chemical structure of haemoglobin
dThe inhaled CO adversely affects the respiratory centre in the brain

AnswerThe answer is (b).

Carbon monoxide binds to haemoglobin about 200 times more strongly than oxygen does, forming carboxyhaemoglobin, which cannot carry oxygen. The blood's oxygen-carrying capacity falls, causing headache, dizziness and, at high levels, death by asphyxia. CO is not converted to CO2 in the body, does not destroy haemoglobin's structure and does not primarily act on the brain's respiratory centre. Remember: CO poisoning = carboxyhaemoglobin.

Why each option is right or wrong
  • (a) CO is not converted to CO2 in the body.
  • (b) Right: CO has a far higher affinity for haemoglobin than oxygen has.
  • (c) CO does not destroy haemoglobin's structure; it occupies the oxygen-binding sites.
  • (d) The main effect is on the blood, not on the respiratory centre.

Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2010, General Studies, Series A. The paper on upsc.gov.in.