UPSC CSE 2018 PRELIMS GS Part - 9 IAS EXAM as to ass Indian Administrative ServicesBY: AAKRITI
51. Which of the following is/are the possible consequence/s of heavy sand mining in riverbeds? 1. Decreased salinity in the river 2. Pollution of groundwater 3. Lowering of the water-table Select the correct answer using the code given below: (a) 1 only (b) 2 and 3 only (c) 1 and 3 only (d) 1,2 and 3
. Answer.b Explanation: Excessive in-stream sand-and-gravel mining causes the degradation of rivers. Instream mining lowers the stream bottom, which may lead to bank erosion. Depletion of sand in the streambed and along coastal areas causes the deepening of rivers and estuaries, and the enlargement of river mouths and coastal inlets. It may also lead to saline-water intrusion from the nearby sea . In-stream sand mining results in the destruction of aquatic and riparian habitat through large changes in the channel morphology.
Impacts include bed degradation, bed coarsening, lowered water tables near the streambed, and channel instability. . The most important effects of in-stream sand mining on aquatic habitats are bed degradation and sedimentation, which can have substantial negative effects on aquatic life. Excessive in-stream sand mining is a threat to bridges, river banks and nearby structures. .Sand mining also affects the adjoining groundwater system and the uses that local people make of the river.
52. With reference to agricultural soils, consider the following statements 1. A high content of organic matter in soil drastically reduces its water holding capacity. 2. Soil does not play any role in the sulphur cycle 3. Irrigation over a period of time can contribute to the salinization of some agricultural lands. Which of the statements given above is/are correct? (a) 1 and 2 only (b) 3 only (c) 1 and 3 only (d) 1, 2 and 3
. Answer.b . Explanation:Plants obtain nutrients from two natural sources: organic matter and minerals. . Organic matter includes any plant or animal material that returns to the soil and goes through the decomposition process. . In addition to providing nutrients and habitat to organisms living in the soil, organic matter also binds soil particles into aggregates and improves the water holding capacity of soil
The sulfur cycle is the collection of processes by which sulfur moves to and from rock, waterways and living systems. . The isotopic composition of sedimentary sulfides provides primary information on the evolution of the sulfur cycle. Too much salt can reduce crop production and water infiltration on soils that have been irrigated for 20 years or more. Too little salt can also result in a chemically compacted soil. . The level of sodium (Na) in a soil can result in soil particles or even layers of differing soil profiles forming a compacted layer that the roots do not penetrate.
53. The Partnership for Action on Green Economy (PAGE), a UN mechanism to assist countries transition towards greener and more inclusive economies, emerged at (a) The Earth Summit on Sustainable Development 2002, Johannesburg (b) The United Nations Conference on Sustainable Development 2012, Rio de Janeiro (c) The United Nations Framework Convention on Climate Change 2015, Paris (d) The World Sustainable Development Summit 2016, New Delhi
.Answer.b Explanation:The Partnership for Action on Greern Economy (PAGE) was launched in 2013 as a response to the call at Rio+20 to support those countries wishing to embark on greener and more inclusive growth trajectories. In 2012, Rio+20 (the United Nations Conference on Sustainable Development) was held in Brazil. The conference's outcome document entitled: "The Future We Want" was a call to action for governments, business and the UN alike to support countries interested in transition to a green economy.
54. "3D printing" has applications in which of the following? 1. Preparation of confectionery items 2. Manufacture of bionic ears 3. Automotive industry 4. Reconstructive surgeries 5. Data processing technologies Select the correct answer using the code given below: (a) 1, 3 and 4 only (b) 2, 3 and 5 only (c) 1 and 4 only (d) 1, 2, 3, 4 and 5
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