2000 General Studies, all questions
UPSC Prelims 2000 · General Studies
Question 123: Science and Technology
The sensation of fatigue in the muscles after prolonged strenuous physical work is caused by
aa decrease in the supply of oxygen
bminor wear and tear of muscle fibres
cthe depletion of glucose
dthe accumulation of lactic acid
AnswerThe answer is (d).
In hard exercise the muscles run short of oxygen and break down glucose without oxygen, producing lactic acid. The build-up of lactic acid in muscle is the classic explanation of the sensation of fatigue and cramps. After rest, oxygen returns and the acid is cleared.
Why each option is right or wrong
- (a) Oxygen shortage is only the starting point; it is the lactic acid that builds up which causes the fatigue.
- (b) Minor wear and tear of muscle fibres is not the explanation given for the sensation of fatigue.
- (c) Depletion of glucose is not the explanation given for this sensation of fatigue.
- (d) Right: accumulation of lactic acid causes the sensation of fatigue.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2000, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.