UPSC NCERT ECOLOGY AND ENVIRONMENT NOTES: TOPIC WISE SOLVED MCQ’s

 

UPSC ECOLOGY AND ENVIRONMENT :

Natural Resources Notes Part 2

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Today’s Topic:Natural Resources

Q1. Consider the following statements:

  1. About 40 percent of the total global evaporation occurs from ocean surface and 60 percent from land surface.
  2. An average retention time of water in the air is about 10 days.

Which of the statements given above is/are correct?

a) Only 1

b) Only 2

c) Both 1 and 2

d) Neither 1 nor 2

Ans:     B

Explanation:    About 84 percent of the total global evaporation occurs from land surface. At any given time, the amount of moisture in the air is only enough to meet a total rainfall requirement of 10 days. Thus, there is very fast movement of water from ocean and land into the atmosphere, and an average residence time of water in the air is only about 10 days.

Q2. Consider the following statements:

  1. About 23 percent of the total rainfall on earth is received on the sea surface.
  2. There is net loss of 7 percent rainfall water on land.

Which of the statements given above is/are correct?

a) Only 1

b) Only 2

c) Both 1 and 2

d) Neither 1 nor 2

Ans:     D

Explanation:    About 84 percent of the total global evaporation occurs from ocean surface and 16 percent from land surface. About 77 percent of the total rainfall on earth is received on the sea surface and 23 percent on the land. There is a net gain of 7 percent rainfall water on land, and this excess is returned to the oceans by surface runoff through rivers and sub-surface water flows.

Q3. Consider the following statements:

  1. Excessive irrigation in semi-arid and arid regions increases the crop productivity of that regions.
  2. The continuous depletion of groundwater along the coastal regions leads to the spoiling of water quality of freshwater wells.

Which of the statements given above is/are correct?

a) Only 1

b) Only 2

c) Both 1 and 2

d) Neither 1 nor 2

Ans:     B

Explanation:    Excessive irrigation in semi-arid and arid regions can cause salt accumulation in the soil, due to which crop productivity may decline. The continuous depletion of groundwater along the coastal regions leads to the movement of saline sea water into freshwater wells, spoiling they water quality.

Q4. Consider the following statements:

  1. Estuaries become more saline and consequently less productive when surface waters are overdrawn.
  2. Uncontrolled soil erosion results in sedimentation of waterways that can harm fisheries.

Which of the statements given above is/are correct?

  1. a) Only 1 b) Only 2         c) Both 1 and 2                        d) Neither 1 nor 2

Ans:     C

Explanation:    The continuous depletion of groundwater along the coastal region often leads to the movement of saline sea water into freshwater wells, spoiling their water quality. Estuaries become more saline and consequently less productive when surface waters are overdrawn.

Heavy rainfall results in rapid runoff from areas having exposed soil, particularly on mountain slopes. This is not only causes soil erosion, but puts lowland areas at extreme risk of destruction due to flooding. Uncontrolled soil erosion results in sedimentation of water ways that can harm fisheries.

Q5. Which of the following are the approaches for conservation of water?

  1. Construction of dams and reservoirs.
  2. Desalinization of seawater and saline groundwater.
  3. Regular dredging and destination of water bodies.

a) Only 1 and 2

b) Only 1 and 3

c) Only 2 and 3

d) 1, 2 and 3

Ans.     D

Explanation:    Important water management approaches to provide a sustainable supply of high quality water are:

(i) Construction of dams and reservoirs to ensure year-round supply of water and controlling floods.

(ii) Desalinization of seawater and saline groundwater, making it fit for drinking and other purposes.

(iii) Regular dredging and desiltation of water bodies.

Q6. Consider the following statements:

  1. Earth’s one-fourth area is formed by land.
  2. The wetlands are transitional zones between terrestrial and aquatic areas.

Which of the statements given above is/are correct?

a) Only 1

b) Only 2

c) Both 1 and 2

d) Neither 1 nor 2

Ans:     C

Explanation:    Earth’s one-fourth area is formed by land, which is largly covered with natural forests, grasslands, wetlands, and man made urban and rural settlements along with agriculture. Low-lying areas covered with shallow water are called wetlands. The wetlands are transitional zones between terrestrial and aquatic areas.

Q7. Consider the following statements:

  1. The forests are storehouse of biodiversity and provide important environmental services to mankind.
  2. Forests regulate floods and drought and the global biochemical cycles.

Which of the statements given above is/are correct?

a) Only 1

b) Only 2

c) Both 1 and 2

d) Neither 1 nor 2

Ans:     C

Explanation:    Approximately one third of the earth’s total land area is covered by forest. The forests are storehouse of biodiversity and provide important environmental services to mankind. Forests improve atmospheric and temperature conditions and enhance the economic and environmental value of the landscape. They effectively regulate floods and drought, and the global biochemical cycles, particularly of carbon.

Q8. Which of the following are the causes of deforestation of forests?

  1. Expansion of agriculture
  2. Urbanization
  3. Industrialization
  4. Cattle grazing

a) Only 1 and 2

b) Only 3 and 4

c) Only 1, 2 and 4

d) Only 1, 2, 3 and 4

Ans:     D

Explanation:    The main causes of deforestation are expansion of agriculture, urbanization, industrialization, excessive commercial use of timber, fuel wood, other forest products and cattle grazing. The current deforestation rate in tropics is estimated to be more than 10 million haper year if this rate of deforestation continues, it is feared that remaining tropical forests may disappear within a century.

Q9. Consider the following statements:

  1. Removal of forests increases the runoff water flowing into rivers and streams.
  2. Soil erosion and soil fertility increases over to deforestation.

Which of the statements given above is /are correct?

a) Only 1

b) Only 2

c) Both 1 and 2

d) Neither 1 nor 2

Ans:     A

Explanation:    Forests, particularly on mountains, provide considerable protection from floods by trapping and absorbing precipitation, and slowly releasing it later. When the forest is removed, the amount of runoff water flowing into rivers and streams increases several fold. Deforestation results in increased soil erosion and decreased soil fertility

Q10. Which of the following are the consequences of deforestation?

  1. Extinction of plant species
  2. Threatens indigenous people
  3. Rainfall increases
  4. Global warming

a) Only 1, 2 and 3

b) Only 1, 2 and 4

c) Only 3 and 4

d) Only 1, 2, 3 and 4

Ans:     B

Explanation:    Deforestation causes the extinction of plant, animal and microbial species. It also threatens indigenous people, whose culture and physical survival depends upon the forests. Deforestation also induces regional and global climate change. Generally, rainfall declines in deforested areas and droughts become common. Deforestation contributes to global warming by releasing stored carbon into the atmosphere as carbon into the atmosphere as carbon dioxide, which is a greenhouse gas.

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