UPSC Prelims 1996 · General Studies
Question 106: Environment and Ecology
Physico-chemical characteristics of water in water sources undergo changes due to
AnswerThe answer is (c).
Effluents, the industrial and municipal wastes released into water bodies, change the physical and chemical characteristics of water, such as its pH, dissolved oxygen, temperature and toxicity. Macrophytes, fungi and evapotranspiration can alter water in small natural ways, but effluents are the major cause of change. Remember: effluents - the main man-made source of water pollution.
Why each option is right or wrong
- (a) Aquatic macrophytes alter water only slightly, in natural cycles.
- (b) Aquatic fungi do not change water quality to a major degree.
- (c) Right: effluents change the physico-chemical characteristics of water.
- (d) Evapotranspiration concentrates water slightly but is not the major cause.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 1996, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.