2024 GS Paper I, all questions
UPSC Prelims 2024 · GS Paper I
Question 33: Science and Technology
Which one of the following is synthesised in human body that dilates blood vessels and increases blood flow ?
aNitric oxide
bNitrous oxide
cNitrogen dioxide
dNitrogen pentoxide
AnswerUPSC’s answer is (a).
Nitric oxide (NO) is made in the body, in the lining of blood vessels, from the amino acid arginine. It relaxes the smooth muscle in vessel walls, dilating the vessels and increasing blood flow; this is why it is central to blood pressure control. Nitrous oxide is laughing gas, used as an anaesthetic. Nitrogen dioxide is an air pollutant. Remember: nitric oxide is the body's own vasodilator.
Why each option is right or wrong
- (a) Right: nitric oxide is synthesised in the body and dilates blood vessels.
- (b) Wrong: nitrous oxide is laughing gas, an anaesthetic, not made in the body to widen vessels.
- (c) Wrong: nitrogen dioxide is a toxic air pollutant.
- (d) Wrong: nitrogen pentoxide is a compound used in industry, not made by the body to widen vessels.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2024, General Studies Paper I, Series A. The paper on upsc.gov.in.