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UPSC Prelims 2021

100 questions, in the order they were asked.

2021 · Q51Environment & EcologySustainable Agriculture & Forestrydifficult

How is permaculture farming different from conventional chemical farming? 1. Permaculture farming discourages monocultural practices but in conventional chemical farming, monoculture practices are predominant. 2. Conventional chemical farming can cause increase in soil salinity but the occurrence of such phenomenon is not observed in permaculture farming. 3. Conventional chemical farming is easily possible in semi-arid regions but permaculture farming is not so easily possible in such regions. 4. Practice of mulching is very important in permaculture farming but not necessarily so in conventional chemical farming. Select the correct answer using the code given below.

  1. (a)1 and 3
  2. (b)1, 2 and 4
  3. (c)4 only
  4. (d)2 and 3
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Official answer(b) 1, 2 and 4

2021 · Q56Environment & EcologyInternational Environmental Treaties & Summitsmoderate

Consider the following statements : 1. The Global Ocean Commission grants licences for seabed exploration and mining in international waters. 2. India has received licences for seabed mineral exploration in international waters. 3. 'Rare earth minerals' are present on seafloor in international waters. Which of the statements given above are correct?

  1. (a)1 and 2 only
  2. (b)2 and 3 only
  3. (c)1 and 3 only
  4. (d)1, 2 and 3
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Official answer(b) 2 and 3 only

2021 · Q59Environment & EcologySustainable Agriculture & Forestrymoderate

In the context of India's preparation for Climate-Smart Agriculture, consider the following statements : 1. The 'Climate-Smart Village' approach in India is a part of a project led by the Climate Change, Agriculture and Food Security (CCAFS), an international research programme. 2. The project of CCAFS is carried out under Consultative Group on International Agricultural Research (CGIAR) headquartered in France. 3. The International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) in India is one of the CGIAR's research centres. Which of the statements given above are correct?

  1. (a)1 and 2 only
  2. (b)2 and 3 only
  3. (c)1 and 3 only
  4. (d)1, 2 and 3
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Official answer(d) 1, 2 and 3

2021 · Q60Environment & EcologyEcosystems & Ecology Conceptseasy

"Leaf litter decomposes faster than in any other biome and as a result the soil surface is often almost bare. Apart from trees, the vegetation is largely composed of plant forms that reach up into the canopy vicariously, by climbing the trees or growing as epiphytes, rooted on the upper branches of trees." This is the most likely description of

  1. (a)coniferous forest
  2. (b)dry deciduous forest
  3. (c)mangrove forest
  4. (d)tropical rain forest
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Official answer(d) tropical rain forest

2021 · Q61Environment & EcologyEcosystems & Ecology Conceptsmoderate

The vegetation of savannah consists of grassland with scattered small trees, but extensive areas have no trees. The forest development in such areas is generally kept in check by one or more or a combination of some conditions. Which of the following are such conditions? 1. Burrowing animals and termites 2. Fire 3. Grazing herbivores 4. Seasonal rainfall 5. Soil properties Select the correct answer using the code given below.

  1. (a)1 and 2
  2. (b)4 and 5
  3. (c)2, 3 and 4
  4. (d)1, 3 and 5
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Official answer(c) 2, 3 and 4

2021 · Q63Environment & EcologySustainable Agriculture & Forestrymoderate

Consider the following statements : 1. Moringa (drumstick tree) is a leguminous evergreen tree. 2. Tamarind tree is endemic to South Asia. 3. In India, most of the tamarind is collected as minor forest produce. 4. India exports tamarind and seeds of moringa. 5. Seeds of moringa and tamarind can be used in the production of biofuels. Which of the statements given above are correct?

  1. (a)1, 2, 4 and 5
  2. (b)3, 4 and 5
  3. (c)1, 3 and 4
  4. (d)1, 2, 3 and 5
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Official answer(b) 3, 4 and 5

2021 · Q66Science & TechnologyBiotechnology & Geneticsmoderate

In the context of hereditary diseases, consider the following statements : 1. Passing on mitochondrial diseases from parent to child can be prevented by mitochondrial replacement therapy either before or after in vitro fertilization of egg. 2. A child inherits mitochondrial diseases entirely from mother and not from father. Which of the statements given above is/are correct?

  1. (a)1 only
  2. (b)2 only
  3. (c)Both 1 and 2
  4. (d)Neither 1 nor 2
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Official answer(c) Both 1 and 2

2021 · Q72Science & TechnologyEnergy & Environmentmoderate

With reference to street-lighting, how do sodium lamps differ from LED lamps? 1. Sodium lamps produce light in 360 degrees but it is not so in the case of LED lamps. 2. As street-lights, sodium lamps have longer life span than LED lamps. 3. The spectrum of visible light from sodium lamps is almost monochromatic while LED lamps offer significant colour advantages in street-lighting. Select the correct answer using the code given below.

  1. (a)3 only
  2. (b)2 only
  3. (c)1 and 3 only
  4. (d)1, 2 and 3
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Official answer(c) 1 and 3 only