IAs Mains Optional Geography Paper 2019 Paper 1 – Section a with Solutions and Explanations (Download PDF)

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IAS Mains Optional Geography Paper 2019 Paper 1 - Section A With Solutions and Explanations given in the videos

Section- A Answer the following in about 150 words each: 10 × 5 = 50

1. a. Describe phreatic eruption and their consequences.

Vulcanicity, Volcanoes - Types and 5 Basis for Classification (Examrace - Dr. Manishika)
Goh Cheng Leong Chapter 3: Vulcanism and Earthquakes (Physical and Human Geography)

1. b. Explain the techniques to calculate potential evapotranspiration suggested by Thornthwaite.

3 Climatic Classification - Koppen, Trewartha, Thornthwaite (Examrace - Dr. Manishika)
  • sheep or cattle trample grass.

1. c. How are sandspits and tombolos formed?

Coastal Landforms (by Waves & Currents): 18 Erosional & 18 Depositional Features
Goh Cheng Leong Chapter 10: Coastal Landforms

1. d. Amensalism is a biotic factor that determines the geographic limits of species. Explain.

  • Negative & Neutral
  • There are basically two types of amensalism: competition and antibiosis. In competition, a larger or more powerful organism excludes another organism from its source of shelter or food. In antibiosis, one organism secretes a chemical that kills the other organism, while the one that secreted the chemical is unharmed.

1. e. How do mountaineers constitute a threat to Mount Everest?

  • DTE - Aug 2019
Mountaineers Constitute a Threat to Mount Everest
  • DTE - August 2019
  • The infrastructure and the allied services around these expeditions began formalising to meet a growing demand of enthusiasts. Fewer than 2,000 people had climbed the Everest in the 1980s, but more than 4,000 did in each of the following decades.
  • Oxygen supply is exhausted as they line up for queue
  • fatal situation as an average human can only metabolise 30 per cent of the oxygen than the usual intake and metabolism at sea level.
  • Often, inexperienced climbers succumb to the fatigue, start hallucinating and ultimately die from exhaustion or fall.
  • On May 22,2019, as many as 220 climbers had attempted to reach the summit within a window that was as small as just two days - May 21 - 23.
  • 11 people died in 2019
  • More garbage and human waste, landfills, health hazards
  • The two most popular routes to the Everest are along the Southeast Ridge (Nepal) and Northeast Ridge (Tibet) . While the traffic of climbers through the Southeast Ridge has traditionally been higher, things are changing rapidly as many expedition companies are shifting their operations to Tibet owing to poor regulations and overcrowding on the south side.

2. a. Why is it necessary to conserve genetic diversity of species? Do protected areas serve any useful purpose in this context? 20

  • Insitu Exsitu - UN Convention on Biological Diversity
Insitu & Exsitu Conservation; Topological and Non-Topological Conservation

2. b. Compare and contrast different types of plate boundaries. 15

Plate Tectonics - 5 Elements, 3 Process and 3 Boundaries with Illustrations

2. c. Explain the nature of urban climates and their impact on global environmental change. 15

  • DTE July 2019

3. a. Discuss in detail the tri cellular model of atmospheric circulation. 20

3 Models of Circulation - Palmen Heat Convective Model & Rossby Waves in Climatology

3. b. How are soil acidity and alkalinity related to soil fertility? 15

Soil Acidity and Alkalinity Related to Soil Fertility
  • Nitrogen (N) , Potassium (K) , and Sulfer (S) are major plant nutrients that appear to be less affected directly by soil pH than many others
  • At acidic pH values, phosphate ions react with aluminum (Al) and iron (Fe) to again form less soluble compounds. Most of the other nutrients (micronutrients especially) tend to be less available when soil pH is above 7.5, and in fact are optimally available at a slightly acidic pH, e. g. 6.5 to 6.8. The exception is molybdenum (Mo) , which appears to be less available under acidic pH
  • The availability of some plant nutrients is greatly affected by soil pH. The “ideal” soil pH is close to neutral, and neutral soils are considered to fall within a range from a slightly acidic pH of 6.5 to slightly alkaline pH of 7.5. It has been determined that most plant nutrients are optimally available to plants within this 6.5 to 7.5 pH range, plus this range of pH is generally very compatible to plant root growth.

3. c. “The web of life is seamless and the consequences of disruption to one part of the ecosystem ripple through the whole.” Elaborate. 15

4 Concepts & Exceptions in Ecosystem - Food Chain, Food Web, Pyramids, Biomagnification

4. a. Discuss the methods of measuring the intensity and magnitude of earthquakes. How are seismic zones demarcated? 20

Earthquakes - Causes, Distribution, Impact & 4 Types of Waves (Examrace - Dr. Manishika)
  • Bureau of Indian Standards [IS-1893 (Part- 1) : 2002] , based on the past seismic history, grouped the country into four seismic zones, viz. Zone-II, -III, -IV and -V. Of these, Zone V is the most seismically active region, while zone II is the least. The Modified Mercalli (MM) intensity, which measures the impact of the earthquakes on the surface of the earth, broadly associated with various zones, is as follows: Seismic Zone Intensity on
  • MM scale II (Low intensity zone) VI (or less)
  • III (Moderate intensity zone) VII
  • IV (Severe intensity zone) VIII
  • V (Very severe intensity zone) IX (and above)
  • Zone-V comprises of entire northeastern India, parts of Jammu and Kashmir, Himachal Pradesh, Uttaranchal, Rann of Kutch in Gujarat, parts of North Bihar and Andaman & Nicobar Islands. Zone-IV covers remaining parts of Jammu & Kashmir and Himachal Pradesh, Union Territory of Delhi, Sikkim, northern parts of Uttar Pradesh, Bihar and West Bengal, parts of Gujarat and small portions of Maharashtra near the west coast and Rajasthan. Zone-III comprises of Kerala, Goa, Lakshadweep islands, remaining parts of Uttar Pradesh, Gujarat and West Bengal, parts of Punjab, Rajasthan, Madhya Pradesh, Bihar, Jharkhand, Chhattisgarh, Maharashtra, Orissa, Andhra Pradesh, Tamilnadu and Karnataka. Zone-II covers remaining parts of the country.

4. b. The impact of floods on life and property can be most effectively reduced by hazard mapping. Comment. 15

Floods & Droughts in India - Causes, Impact & Control Measures (Examrace)
  • US: National Flood Insurance Program
  • Flood hazard mapping delineates flood hazard areas along streams and lakes using design flood levels established as part of flood hazard studies
  • Flood hazard mapping is an exercise to define those coastal areas which are at risk of flooding under extreme conditions

4. c. How are Ocean waves formed? Distinguish between a wave of oscillation and a wave of translation. 15

5 Secrets to Understand Waves and Currents - Oceanography
NCERT Class 11 Physical Geography Chapter 14: Movement of Ocean Water|English
  • Waves of oscillation = within the wave the water molecules follow a circular to elliptical orbit and don՚t actually move along with the wave form.
  • Waves of translation = within the wave the water molecules move forward along with the wave form. Form at the beach where waves begin to break.

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- Published/Last Modified on: December 20, 2019

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