1. Prologue
  2. Internal Breakup
  3. Parks
    1. Parks and hills
    2. Parks and rivers
  4. Wildlife, Flora-Fauna
    1. Macaque
    2. Equatorial forests
    3. Swamp Deer
    4. Spider monkey
    5. Mammals
  5. Agro/soil related
    1. Mycorrhizal biotech
    2. Biofertilizers
    3. Nitro cycle
    4. Contour
    5. Sugar byproducts
  6. Pollution Related
    1. E-waste
    2. Water pollutants
    3. Water consumption in industries
    4. Acid Rain
    5. Smog
  7. Ecology theory related
    1. food chain
    2. Niche
    3. Decomposers
    4. Ecological succession
    5. Ecosystem productivity


  • In UPSC prelims 2013 General studies paper, 22 out 100 MCQs were from environment and biodiversity (EnB). Last year (2012) it was 23. So UPSC’s obsession/infatuation with EnB has remained or less the same.
  • Like last year, few question on agriculture related things (bio-fertilizers, soil conservation etc.)
  • Nothing from EnB related Acts/ policy/ Polity / judgments.
  • Nothing from the three major conferences (RIO+20, Doha and Hyderabad). Although doesn’t mean preparation has gone in vein because those topics remain important and relevant for Mains.

Internal Breakup

Chart CSAT 2013 Environment section

National Parks 2
Wildlife flora n fauna 5
Pollution related 5
Agro 5
Ecological Theory 5
Total 22


Parks and hills

1. Consider the following pairs:

  1. Nokrek Bio-sphere Reserve : Garo Hills
  2. Logtak (Loktak) Lake : Barail Range
  3. Namdapha National Park : Dafla Hills

Which of the above pairs is/are correctly matched?

  1. 1 only
  2. 2 and 3 only
  3. 1, 2 and 3
  4. None

As per tourism website of Meghalaya government, Nokrek is the highest peak in Garo Hills.=>#1 is right.

If you observe the school atlas, Loktak lake and Barail range are away from eachother =>#2 is wrong.

Eliminate options accordingly

  1. 1 only
  2. 2 and 3 only
  3. 1, 2 and 3
  4. None

Thus answer=>A only 1.

Parks and rivers

2. Consider the following pairs about parks and rivers passing through them:

  1. Corbett National Park: Ganga
  2. Kaziranga National Park: Manas
  3. Silent Valley National Park: Kaveri

Which of the above pairs is/are correctly matched?

  1. 1 and 2
  2. 3 only
  3. 1 and 3
  4. None
Option Rivers passing
  1. Corbett National Park : Ganga
River Ramganga (West) and River Kosi
  1. Kaziranga National Park : Manas
Brahmaputra, Diphlu, Mora Diphlu and Mora Dhansiri
  1. Silent Valley National Park : Kaveri
Bharathapuzha ,River Kunthi

Ans: (D) None of the rivers flow through these Parks.

Wildlife, Flora-Fauna


1. In which of the following States is lion-tailed macaque found in its natural habitat?

  1. Tamil Nadu
  2. Kerala
  3. Karnataka
  4. Andhra Pradesh

Select the correct answer using the codes given below.

  1. 1, 2 and 3 only
  2. 2 only
  3. 1, 3 and 4 only
  4. 1, 2, 3 and 4

Lion Tailed Macaque had been in news because last year, IUCN took it off the list of World’s 25 Most Endangered Primates’ list.

As per: iucnredlist, this Macaque is found in India (Karnataka, Kerala, Tamil Nadu)

Eliminate choices accordingly,

  1. 1, 2 and 3 only
  2. 2 only    
  3. 1, 3 and 4 only
  4. 1, 2, 3 and 4

Thus answer=> A

Equatorial forests

2. Which of the following is/are unique characteristic/characteristics of equatorial forests?

  1. Presence of tall, closely set trees with crowns forming a continuous canopy
  2. Coexistence of a large number of species
  3. Presence of numerous varieties of epiphytes

Select the correct answer using the code given below:

  1. 1 only
  2. 2 and 3 only
  3. 1 and 3 only
  4. 1, 2 and 3
  • In equatorial rainforest,..fourth layer is canopy layer. The tall trees grow so close together that their crowns interlock to form a continuous canopy which blocks out the sunlight in forest (O level geography By Francis Mathews Green)=>#1 correct.
  • #2 is correct as such.
  • Tropical forest is found in equatorial and tropical zones…..Epiphytes are also common. (Geography By Surender Singh) =>#3 correct.

Hence answer (D) 1, 2 and 3 correct.

Swamp Deer

3. Consider the following fauna of India:

  1. Gharial
  2. Leatherback turtle
  3. Swamp deer

Which of the above is/are endangered?

  1. 1 and 2 only
  2. 3 only
  3. 1, 2 and 3
  4. None

As per IUCN, 1, 2 are critically endangered. 3 is vulnerable. So (A) 1 and 2 only.
Some websites mention Swamp deer to be endangered but as per the official page on IUCN (click me) it is shown as vulnerable (that is one step less than endangered).
Update Jun-26-2014: UPSC uploaded official answerkey. Correct answer is: all of them. Hence for swamp deer is seems UPSC examiner used sarkari website data.

Spider monkey

4. Consider the following

  1. Star tortoise
  2. Monitor lizard
  3. Pygmy hog
  4. Spider monkey

Which of the above found in India?

  1. 1, 2 and 3 only
  2. 2 and 3 only
  3. 1 and 4 only
  4. 1, 2, 3 and 4

1, 2, and 3 are found in India if we refer iucnredlist.org

While spidermonkey lives in forests from southern Mexico through Central and South America to Brazil (Britannica) Hence answer (A) only 1,2 and 3.


5. Consider the following animals:

  1. Sea cow
  2. Sea horse
  3. Sea lion

Which of the above is/are mammal/mammals?

  1. 1 only
  2. 1 and 3 only
  3. 2 and 3 only
  4. 1, 2 and 3

Mammal are animals in which the young are nourished with milk from special mammary glands of the mother.

Mammal yes/no? As per Britannica
Sea Cow Yes Sea cow, very large aquatic mammal.
Sea Horse No Sea Horses fall under gasterosteiform fish order.Reproductive behaviour of sea horses is notable in that the male carries the fertilized eggs.Once the eggs hatch, the male convulses his body and expels the young through a single opening in the pouch.

The young receive no further care from parents=> no milk involved, hence not mammal.

Sea Lion Yes mammals under under Otariidae family.

Hence answer (B) 1 and 3 only.

Agro/soil related

Mycorrhizal biotech

1. Mycorrhizal biotechnology has been used in rehabilitating degraded sites because mycorrhiza enables the plants to

  1. resist drought and increase absorptive area
  2. tolerate extremes of PH
  3. Resist disease infestation

Select the correct answer using the codes given below:

  1. 1 only
  2. 2 and 3 only
  3. 1 and 3 only
  4. 1, 2 and 3

As per page 187-188 of Plant Biotechnology By Rita Singh,

  • Mycorrhizal plants have tolerance to adverse soil, PH, high temp., drought and toxic heavy metals.
  • The most important role of Mycorrhizal fungi is to absorb nutrient and water from soil and transfer them to their hosts.
  • Mycorrhizae helps plants withstand root diseases…the oxalic acid production by mycorrhizal fungi contributes to disease suppression.

Hence all three statements are correct. Answer (D).


2. Consider the following organisms

  1. Agaricus
  2. Nostoc
  3. Spirogyra

Which of the above is / are used as biofertilizer / biofertilizers

  1. 1 and 2
  2. 2 only
  3. 2 and 3
  4. 3 only

Nostoc is a species of blue-green algae used as biofertilizer (TheHindu 2002 article).=>Hence #2 is correct.

As per Page 251 Biotechnology of Biofertilizers by Sadasivam Kannaiyan

…Although, the algae grow on their own in the rice fields, but all of them are not beneficial to crop. The green algae like Spirogyra compete with the crop for nutrient and reduce tilering in the crop.=> #3 is incorrect.

  1. 1 and 2
  2. 2 only
  3. 2 and 3
  4. 3 only

Agaricus is a mushroom, haven’t found reference for its use as biofertilizer. So answer (B) only 2 (or may be A hahaha)

Nitro cycle

3. Which of the following adds / add nitrogen to the soil?

  1. Excretion of urea by animals
  2. Burning of coal by man
  3. Death of vegetation

Select the correct answer using the codes given below.

  1. 1 only
  2. 2 and 3 only
  3. 1 and 3 only
  4. 1, 2 and 3

NIOS EnB Chapter 5(Page 88): Nitrogenous Waste products of Living organisms such as urea and uric acid and dead remains of organisms are converted back to inorganic ammonia by the bacteria=>1 and 3 is correct.

  • There is no mention of burning of coal in this N cycle section. Moreover, in the same chapter, it is mentioned that burning of biomass releases CO2 into the atmosphere as part of Carbon Cycle.=>2 is incorrect.
  • Although some websites do mention coal-burning power stations are responsible for emissions of millions of tons of sulfer and nitrous oxide. But that is adding nitrogen into “atmosphere” and not “soil” as such.  hence statement #2 is false.

Eliminate options accordingly

  1. 1 only
  2. 2 and 3 only
  3. 1 and 3 only
  4. 1, 2 and 3

Hence Answer (C) 1 and 3


4. Contour bunding is a method of soil conservation used in

  1. desert margins, liable to strong wind action
  2. low flat plains, close to stream courses, liable to flooding
  3. scrublands, liable to spread of weed growth
  4. None of the above

As per the Indian Geography book by Khullar(Page 180)

Contour Bunding is associated with terracing, to check the flow of water on a hill slope in order to reduce soil erosion.

As per Britannica

Contour bunding (or contour bundling), involves the placement of lines of stones along the natural rises of a landscape. It helps to capture and hold rainfall before it can become runoff. It also inhibits wind erosion by keeping the soil heavy and moist.

As per Human Geography: The Land By Pradeep Sharma

Terracing and contour bunding across the hill slops is a very effective and one of the oldest methods of soil conservation.….They divide hillslopes into numerous small slopes, checks the flow of water, promotes absorption of water by soil and saves soil from erosion.

from ^these references, we can conclude that contour bunding is associated with hill slops and meant for protecting soil from erosion by rainwater.

  • desert margin, strong wind action =>A is incorrect.
  • low flat plains, stream course=> B is incorrect.
  • scrubland and weed growth=>C is incorrect.

Hence answer is (D) none of above.

Sugar byproducts

5. With reference to the usefulness of the by-products of sugar industry, which of the following statements is / are correct?

  1. Bagasse can be used as biomass fuel for the generation of energy.
  2. Molasses can be used as one of the feedstocks for the production of synthetic chemical fertilizers.
  3. Molasses can be used for the production of ethanol.

Select the correct answer using the codes given below.

  1. 1 only
  2. 2 and 3 only
  3. 1 and 3 only
  4. 1, 2 and 3

Recall Bagasse Cogeneration topic from article on Economic Survey Ch.11=>statement 1 is correct.

Recall Ethanol blending article=>statement 3 is correct.

and I haven’t been able to dig any reference where molasses is used for production of chemical fertilizers.=>#2 is incorrect.

Eliminate answers accordingly

  1. 1 only
  2. 2 and 3 only
  3. 1 and 3 only
  4. 1, 2 and 3

Thus we are left with answer (C)

Pollution Related


1. Due to improper / indiscriminate disposal of old and used computers or their parts, which of the following are released into the environment as e-waste?

  1. Beryllium
  2. Cadmium
  3. Chromium
  4. Heptachlor
  5. Mercury
  6. Lead
  7. Plutonium

Select the correct answer using the codes given below.

  1. 1, 3, 4, 6 and 7 only
  2. 1, 2, 3, 5 and 6 only
  3. 2, 4, 5 and 7 only
  4. 1, 2, 3, 4, 5, 6 and 7

As per pib.nic.in,

  • Heptachor is an insecticide.
  • Stockholm Convention on Persistent Organic Pollutants aims to eliminate its usage.

So, eliminate choices involving heptachlor (#4)

  1. 1, 3, 4, 6 and 7 only
  2. 1, 2, 3, 5 and 6 only
  3. 2, 4, 5 and 7 only
  4. 1, 2, 3, 4, 5, 6 and 7

we are left with answer (B).

Another approach is looking @plutonium (#7), which is radioactive and hence not used in day to day computer/electronic items as such. Eliminate choices involving #7 and you’re still left with (B).

Water pollutants

2. Which of the following can be found as pollutants in the drinking water in some parts of India?

  1. Arsenic
  2. Sorbitol
  3. Fluoride
  4. Formaldehyde
  5. Uranium

Select the correct answer using the codes given below.

  1. 1 and 3 only
  2. 2, 4 and 5 only
  3. 1, 3 and 5 only
  4. 1, 2, 3, 4 and 5

In the earlier e-waste question, you could apply common sense that plutonium, being radioactive, is not used in day to day electronic items. However, same analogy/common-sense cannot be applied here that uranium, being radioactive, is not part of drinking water pollution.

Because uranium in ground water is indeed a problem in Punjab and leading to birth of mentally retarded children. Both Indianexpress and TheHindu have been highlighting this story.

So answer must contain uranium (#5). This eliminates option A.

Arsenic (#1) and Fluoride (#3) are well known water pollutants. So answer must contains #1 and #3.

  1. 1 and 3 only
  2. 2, 4 and 5 only
  3. 1, 3 and 5 only
  4. 1, 2, 3, 4 and 5

Sorbitol (#2) used as artificial sweetener and laxative. Formaldehyde (#4) used in coating, laminating etc. Neither of them not as famous water pollutants as arsenic and fluoride.

Accordingly Answer (C): only 1, 3 and 5. (or debatable D)

Water consumption in industries

3. Which one among the following industries is the maximum consumer of water in India?

  1. Engineering
  2. Paper and pulp
  3. Textiles
  4. Thermal power

As per TERI policy brief of Dec 2012, Page 2, Table 1

Sector Percentage of water consumed
Thermal power plants 87.87
Engineering 5.05
Pulp and paper 2.26
Textiles 2.07
Steel 1.29
Sugar 0.49
Fertilizer 0.18
Others 0.78
Total 100

Hence answer is (D) thermal power.

Acid Rain

4. Acid rain is caused by the pollution of environment by

  1. carbon dioxide and nitrogen
  2. carbon monoxide and carbon dioxide
  3. ozone and carbon dioxide
  4. nitrous oxide and sulphur dioxide

As per NIOS EnB Chapter 10, page 167, Table 10.3 Ans: (D)


5. Photochemical smog is a resultant of the reaction among

  1. NO2, 03 and peroxyacetyl nitrate in the presence of sunlight
  2. CO, 02 and peroxyacetyl nitrate in the presence of sunlight
  3. CO, CO2 and N02 at low temperature
  4. High concentration of N02, O3 and CO in the evening

Answer is (A), as per the chemical equations given in NCERT Chemistry class 11, Chapter 14, Page 404

Ecology theory related

food chain

1. With reference to food chains in ecosystems, consider the following statements:

  1. A food chain illustrates the order in which a chain of organisms feed upon each other.
  2. Food chains are found within the populations of a species.
  3. A food chain illustrates the numbers of each organism which are eaten by others.

Which of the statements given above is / are correct?

  1. 1 only
  2. 1 and 2 only
  3. 1, 2 and 3
  4. None

#1 is correct because food chain shows the “order / sequence” of feeding.

Food chains are not found within the populations of ‘a’ species, because technically, Food chain is the sequence of organisms through which the energy flows. If the species starts eating itself, then flow of energy will not proceed => 2 is wrong.

Food chain doesn’t show “numbers” of each organism eaten by others=> #3 is wrong. This eliminates (C)

Hence we are left with answer (A) only 1.


2. Which one of the following terms describes not only the physical space occupied by an organism, but also its functional role in the community of organisms?

  1. Ecotone
  2. Ecological niche
  3. Habitat
  4. Home range

IGNOU EnB material, Chapter 4, Page 73

  • Gause’s competitive exclusion principle states that two species having identical requirements can not occupy the same ‘niche’ indefinitely.
  • This brings us to the question-what is a niche? A species niche is its unique functional role or place in an ecosystem. Hence answer=B

for more, refer NIOS EnB chapter 4 principles of Ecology.


3. With reference to the food chains in ecosystems, which of the following kinds of organism is / are known as decomposer organism/organisms?

  1. Virus
  2. Fungi
  3. Bacteria

Select the correct answer using the codes given below.

  1. 1 only
  2. 2 and 3 only
  3. 1 and 3 only
  4. 1, 2 and 3

NIOS EnB material, Ch.5, page 78

  • Decomposers: Also called saprotrophs.  These are mostly bacteria and fungi that feed on dead decomposed. Hence 2 and 3 correct.
  • Viruses aren’t decomposers.

Answer (B) 2 and 3 only.

Ecological succession

4. In the grasslands, trees do not replace the grasses as a part of an ecological succession because of

  1. insects and fungi
  2. limited sunlight and paucity of nutrients
  3. water limits and fire
  4. None of the above

Primary succession looks like: lichen => grasses =>trees.  Meaning, trees replaces grasses. The question is why don’t trees replaces grasses in grassland?

Page55, A Textbook on Environmental Studies  By Dr. Rajan Misra

Secondary succession occurs in an area that became bare due to destruction of existing community by fire, draught, landslide, earthquake etc.

Although another interpretation/viewpoint/doubt could be that even after secondary succession, ultimately tree will replace grass under that succession- hence answer should be (D) None of Above.

But that (trees replacing grass) doesn’t always happen with grasslands:

Consider following

  1. Grass ecosystems are an early stage of succession in regions where the mature ecosystems are forests. However, grass ecosystems are climax ecosystems in grassland regions, where there is not enough rainfall to support a forest. (e.g. in our option C water limits and forest fire) (ref. Page 149 Human Ecology: Basic Concepts for Sustainable Development By Gerald G G Marten)
  2. Ecological succession of a grassland is desert. (Page 3.17 Environmental Studies By Anjali Bagad)
  3. Two factors for evolution of temperate grassland biome, i) Extreme continental climate with limited supply of water due to low rainfall, ii) human activities mainly burning of vegetation.” (Ref. Page 619, Physical Geography by Savindra Singh)

Hence answer (C) water limits and fire.

Ecosystem productivity

5. Which one of the following is the correct sequence of ecosystems in the order of decreasing productivity?

  1. Oceans, lakes, grasslands, mangroves
  2. Mangroves, oceans, grasslands, lakes
  3. Mangroves, grasslands, lakes, oceans
  4. Oceans, mangroves, lakes, grasslands

Debatable choices depending on how you look at “productivity”?

Viewpoint #1: Answer (C) (rate)

Page 49, Comprehensive Environmental Studies by J.P. Sharma

Productivity is the rate of organic matter or biomass production. The productivity of an ecosystem is of two types: primary and secondary.

Now, according to one source http://kingfish.coastal.edu/biology/sgilman/770productivitynutrients.htm

  • The average ocean productivity is about 50 grams carbon per square meter per year.
  • Average land productivity is 160 grams carbon per square meter per year.
  • (thus) The productivity of the open ocean (ocean away from coasts) is comparable to desert production.

On this line of logic, the answer choice (Descending order) should be : *** > *** > ***> oceans.
There is only one such option (C).
Besides, as per various sites, mangroves are highly ‘productive’. Hence C is the answer
some more references in favor of Answer (C)

Viewpoint #2: Answer (D) (amount)

As per http://www.world-builders.org/lessons/less/biomes/primaryP.html

  • The total primary productivity of the ocean is about 8 times the primary productivity of all the land surface.
  • Hence in descending order it should be Ocean >*** >**** >grassland. There is only one such option (D)

Anyways, final arbitrator is UPSC’s official answerkey.
Update Jun-26-2014: UPSC uploaded official answerkey. Correct answer is: C. hence they were asking about “Rate”
Thanks Mr. Shiva Ram, Mr. Palas Nuwal, Mr. Manu Jha and Mr. Siriyal Patel for their inputs.
This concludes answerkey for all 100 questions asked in UPSC CSAT 2013 General studies paper.