[Answerkey] CSAT 2013 Environment & Biodiversity (EnB) Questions solved with explanation, reference, all four sets (A,B,C,D)

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Mrunal's Economy Course
  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.

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201 Comments on “[Answerkey] CSAT 2013 Environment & Biodiversity (EnB) Questions solved with explanation, reference, all four sets (A,B,C,D)”

  1. i guess it would be good if others share their marks….good to get an idea of the cutoff….

    i am getting 90+160 = 250……general category…hope its enough for clearing….

    didnt risk much and attempted only 60 in GS….now repenting it…..

    1. i also tried to play safe and attempted only 60 in gs1 with absolutely no fluke or guess work . little bit dissapointed now. hope to get around 106(109)+ 135(140). total around 241 to 249.

    2. around 113 as per mrunal’s key in paper 1 and around 175-183 in 2nd….

      1. I am getting 80(83) paper I + 155(159) paper II total 235 to 240 .
        I am OBC category

        1. It is nice that you people scored very high. Now this is my sincere request to focus on mains instead of wasting time in discussing prelims score. Your high score can demotivate the low scorers & this site never encourage discussing scores & cutt off unlike other sites.

    3. paper-1: 129-138
      paper-2: 117-125
      P.S- I wrecked paper 2 despite being an engineer. lost precious time after mistakenly filling up the attendance OMR sheet incorrectly. No regrets though.

  2. as the upsc combined both the ias and ifs (forest service) exams together this year, i hope this doesnt prove to be disadvantageous to the ones who opted only for the ias and nor forest services and similarly doesnt affect the cut-offs much…i hope somebody could throw some light on this issue plzz… :((

    1. It doesn’t say drinking water/ground water.It just says that in dinfected taps it is found due to the paints used etc., not in ground water

    2. Further there is no such option which inlcudes formaldehede + the 3 others(Uranium,Arsenic & flouride). and sorbitol should not be in the answer. So a little smartwoek there could have helped you :P

    3. Is it found in India? I know formaldehyde is a VOC. But I have not seen articles where they have specifically stated that formaldehyde is polluting drinking water in India. Above all no amount of search gave results in favour of sorbitol. The best answer is C

  3. MRUNAL and fellowmates, i need one help from you.As this is my first attempt and I have selected ENGLISH LITERATURE as mains subject.PLS suggest me some books for mains all GS_1,2,3,4 papers as well as english preferred book lists.
    thanks and regards

    1. well you know i was also inclined to taking english and had,in fact, decided it to be one of the two optionals…but now with only one optional left, i am going for political science ,my other optional in the 2-optionals pattern…with the time crunch coupled with the vast syllabus and most importantly lack of material ,i felt it wouldn’t be wise to hedge my bets on English,though i love it…i hope you have weighed the ifs and buts …on a side note have you done masters in english? i am just a graduate.

      1. yes WASIF,after analysing pub. ad. this year,people got very terrible marks in 2 figures,then i selected some optionals based on strategies n marks-history a evregreen subject,bt syllabus is vast,mreover some subjects lyk pub ad,philosophy,psychology,sociology etc hve unpredicatble questions.I am not sure bt seniors agree that these subjects are unpredicatble in analytical termsso finally i selectd english lit. though the syllabus is vast bt m very fond of english litt. also i have topped english litt subject in my 10th and 12th std..a misadventure..ha ha.i hve engineering background bt m inclined to english litt. though political science is good option,bt i hve my own viewpoint..crrct me if m wrong,as m new in this field,can anyone come up with pros n cons of some optionals..? it will b beneficiary for first attempters lyk me…thnks n regards

        1. Do not go by marks and analysis. Find whether you can sit with the subject for few hours a day and enjoy it. That is THE only criteria. Marks will flow automatically. On the argument that this year Pub admn. has got less marks, next year it will be another subject. You should not choose something based on fear. Not a right way to go forward.

        2. i agree with Rahul that a subject you can spend your day with should be your choice.Will you be able to ace a subject however high-scoring it is if at the slightest pretext you feel like switching to something else.The most important thing that should clinch it for you while deciding is, whether i enjoy it ,it interests me or not because, trust me, in the final analysis that will only translate to marks.About English,congrats on your success in 10 and 12 but i think it is entirely a different kettle of fish at this level and 10,12 are just too juvenile a comparison.But yes as you say that you love English ,go for it by all means.I am myself a graduate(english honours) and love the language like anything but personally i feel the syllabus is too vast(around 44 poems and i forgot how many novels but i counted many!lol)and the time is too short,though i must admit that there is still a part of me that keeps gravitating towards it.after all,nobody can forget his first love!

          1. HI WASIF…n all frnds
            thnks yaar,u re having very gud english.can u suggest me some optionals which are suited for engineering background..i will select among those optionals a/q to my interest..from 26th onwards m just confused abt optional subject.i rea some english lit buks,then i read pub ad,then i m reading some blah blah..finally i hve to decide be4 this sunday bt if u add ur suggestion wit pros n cons of a few optional.it will b helpfull to tke ultimate decesion..

  4. Mrunal Bhai, You referred to a lot of sources to clear doubts about answer to any question, I failed to understand how to start. In a strategy article you have written not to go for multiple books for the same topic, and you refer to different books-and materials for the same topic ! I had thought of reading basic material that you have advised in your articles

    1. The underlying philosophy is to not just use only one book . It is to deliberate and select a single and good source for each topic and keep reading only from it so that you will get familiarity instead of reading the same topic from N number of books which is either feasible nor required.

      1. Single and good source of each topic ! Plz help me if you can, I was reading the geography key provided by Mrunal Bhai, where he has referred to NIOS, NCERT, LuShang(I don’t recall the name correctly) etc., Which source do you believe is a Good Source ?

        There has been reference to different viewpoints too in several solutions he provided, so how is it beneficial to adhere to a single source,

        1. NCERT. Even if the source is wrong sometimes, you can bet that it is the least wrong source of all. And over analysis on such a minute level will kill the fun of preparing Rohit. Go easy and choose what YOU feel is right.

          1. Thankyou Rahul :)

    2. @ रोहित जी आपने बिलकुल ठीक कहा …मे भी यही सोच रहा हू

  5. Thanks Mrunal Sir, for all your contributions and good work…:)

  6. Mrunal sir I thank very much for ur hard work and smart work. ..the way u provide the information is most impressive.
    I hv been following ur blog for 5months ..now I am able to analyse many things just because of ur site.
    And I hv checked all the answer keys and getting hope to pass
    And now I really need ur help as I came from b.tech I am in dilemma whether shd I choose pub adm or sociology
    Plz compare these two optionals together and with respect to weightage of marks in all 5papers..
    It is not only useful for me but also many students…
    Once again my heartly thanks to all ur team….

  7. Thanks Mrunal sir..I haven’t seen anyone putting in so much effort

  8. Damn..I wish I had attempted both th, wasn’t 100% sure..now they seem so obvious… ques on water pollutants..i knew both of them..no risk , no gain :(

  9. I think in this paper, any serious aspirant would hv studied almost every topic they asked ques from. But by making the options tricky dey r just tryin to tell us- Come back on Earth my dear, U need to work even harder n smarter dan dat! Even basic conceptual clarity is not a piece ov cake

    1. I agree with you tanya,people here seems to be scoring above 100 in paper-1 by default.So lets see how many of them clear prelims

  10. sir ur later seems not very near.. pls provide us with some update about mains

  11. Well RB..I wud like to congratulate ppl scorin 100, 120..etc..Infact a serious aspirant at his/her best CAN score 130-140 also..but u tread on a slippery path after dat..u r likely to.lose more dan gain…Upsc asks some questions from their own viewpoint which is hard to guess even if one is well versed wid da topic plus dat sucky all of da above option sometimes

    1. Tanya, to provide a real reference, my friend who has got 138th rank this year has written prelims again and is scoring around 130 in Paper – 1 and 190 in Paper -2 ( obvious for any iit, nit guy).

  12. By default cases- Lol..can’t say man..U nvr know when one might get lucky!

    1. i never thought people with luck can score above 100 marks

  13. Sir, what should be probable cut off as per ur analysis of both the papers.
    I am aware tht it might not be accurate but still what is the harm in a honest guess as per ur view.
    Thank u sir…

  14. Too much discusssions are going on regarding prelims . qualifying upsc requires good marks in mains .i m not going to crack prelims this year. But i need detailed discussions regarding mains.Because one day i hv to appear mains. So plz stop disscussions regarding prelims and start guidance for mains.

  15. I am currently in a central service from 2010 exam and will be getting another central service from 2012 exam.

    My query is:

    1. I want a continuation in service, without break. in that case, can I seek exemption from FC and continue in my present service and then give a technical resignation in December when departmental training starts and join the new service? I have applied “Through Proper Channel” so relieving should not be an issue here. Is exemption given for preparation and will it be considered wrong if I continue to be in job?

    2. What is the quantum of time I can have in the transition phase i.e. after ‘technically’ resigning from last service and joining new service?

    Any suggestions and feedback will be welcome.


  16. Hello everyone…
    Anyone tell me how to prepare ECONOMY as a optional subject for mains.thanx.

  17. any aspirant can score above 100 only if he has basic knowledge, not just by luck

  18. @Tarun n Ram Bihari ji
    I wish people understood the concept of sarcasm..

    1. @Tanya :Probably in the 2014 CSAt (Paper II) they can include a question based on the concept of Sarcasm :D

  19. regarding Q 4. Contour bunding is a method of soil conservation used in?? … the contour bunding is given as “Solutions to desertification” as per Britannica


    .. means contour bunding is also done in desert margin to conserve soil from strong wind action… and it is also written in G C LEONG that contour bunding is done near to desert area to conserve soil and prevent erosion … SO from these reference option A is absolutely correct..

    # In mains 2012 also UPSC asked about causes and remedial measures to desertification.. so may be again want to ask same thing in other way in PT 2013

    1. u r correct buddy ..@mrunal sir plz clarify

    2. Dear, i m searching in GC LEONG but could not found….can u mention the page no. because i also marked A here.

  20. Frnds I request you all to pls share your answer
    for CSAT ppr 2 decision making question no 78 (Sugar allocation)

    All classes have given C OR D as the two best answers
    but i have marked option B..i still think ans should be either B OR C
    Pls share your views as to why option B cannot be right

    1. Its mentioned as ‘You do not want to spoil your friendship with him’ in that question. If you go with B, there are chances that friendship would get spoiled. That’s that I feel and didn’t chose that option.

    2. In the question it is clearly stated that “You do not want to spoil your friendship with him”. Also please check Mrunal sir’s articles on decision making questions. Being rule-bound is not good. So B may not be the right answer.

      I feel in this question even D may be wrong as you are washing your hands off rather than making your friend accepting the government order. It may be C/D or C alone.

      1. @vignesh
        agreed buddy..option D should not be right as it shows that you are running away from your responsibility to save your friendship..so D is out..but the question also mentions ” He expresses annoyance when you tell him about the Government’s restrictions on this matter.He feels that since you are the District Magistrate you can release any amount.”..this indicates that you have already had a discussion on the matter with your friend and still he wants you to (mis)use your power as a DM..so why would you further persuade your friend to accept what is morally right and moreover what is the need to show him the copy of govt restrictions as mentioned in option C..if he is your good friend he should believe you and also understand your stand and responsibility towards the society specially in such times of shortage of goods..so i think even option C cannot be right..that leaves us with option B as i think it is straightforward and upright..if he is your good friend and above all a sensible man he would not break ties with you even if you refuse him extra sugar..but since upsc has two right answers for decision making i think option B or C should be given full marks contrary to C/D as given by many classes in their keys

    3. @aspirant
      same here dude….my thought process was exactly same as of urs so marked B

      1. exactly i also marked B…. i interpreted in same way..also that District magistrate decision making question..all academy has marked C/D…. i don think so D will come..that is a Magistrate moving out to attend other meetin… will nt collect application frm a villager .n QUICKLY note down few answers..it sounds vague n irresponsible for that post…either he/she must call senior subordinate or ask the villager to submit application to junior…B and C both r similar… coz both option means junior to Magistrate…i think B or C s answer any opinion..?

  21. Rahul..kudos to ur friend..ur comment though in good spirit can mislead some..i know a guy who scored just 220 last year ( compared to ur iit guy’s 320) and secured a rank in top 75..so all m sayin is dat it dosent matter whether u r from iit or some c grade college..its ur hard work… everyone has to prove themselves in every single exam…moreover 320 is no different from 220 as dey both qualified n these marks r not even counted….Moral of da story- study for da mains now..prelims n cut off ko bye bye karo

    1. Correct Tanya. Good luck!!!

    2. And wat about 2nd ranked Ms. Rukmani Riar (2011) who got only 199 in pre when cut off was 198 :D :D

    3. Sure Tanya. You rock.

  22. so u mean u have found a totally different meaning of sarcasm great discovery tanya

  23. How does it matter if any one has scored 220 or 330…I am not intrested in him/her and i doubt if nebody really is…my interest is just my marks and my success..(and that does not mean i do not take motivation from succesfull ppl…i do but m not ovwerwhelmed by anything…anything in excess is harmful)..the worst thing (according to me) in this otherwise splendid website is the comment column(though at times there are useful and helping comments too but very few) I know m wasting my time too in commenting gud for nothing comment but after wasting so much time in reading some of the self boasting and some comments boasting others I could not resist myself from commenting… sry for wasting time of those who read this comment but pls guys it is gud that u scred fabulous marks but now wats the use of advertising ur WUD BE marks…and d most irritating comments are “I have scored 250+ marks shud i prepare for mains”….man grow up…i don’t know how u scored 250+ marks…either ur IQ is just zero or ur only motive is to demotivate guys over here… ..newys peace…nd sory if I hurt someone…and yupp best of luk to everyone…

    1. It is part of the exercise and one must take such things in his stride. people are not going to stop. Simple.

    2. And wat about 2nd ranked Ms. Rukmani Riar (2011) who got only 199 in pre when cut off was 198 :D :D

  24. 1. few viruses are aquatic decomposers………so it should be considered while answering……….
    2. agaricus is also used as biofertilizers……
    3. form of counter bunding where stones are used in desert region so option A is correct……also its considered as UN as a method against soil erosion

    plz reply


  25. mrunal bhai plz give main strategy as soon as possible

  26. hi,

    Just an observation…..

    This is what i found out….

    Both Seahorse and Sea horse exit(Mind the space between sea and horse )…. when we say seahorse(no space) it refer to a fish in which male carries eggs(as mentioned by you)…but when we say sea horse as asked in CSAT… it is common name given to Walrus(mammal) which is also called Sea horse… So, i think only UPSC can tell the right answer…because technically when we refer to fish, seahorse is one word there is no space in between……thank you…plz care to comment

    1. Good inference…… But to be honest I think you are dwelling much deep than necessary.

      1. Yes sir… i agree with u… but who knows whats in the mind of UPSC….

  27. A food chain illustrates the order in which a chain of organisms feed upon each other.
    is N’T the WORD “EACH OTHER” should be noted here.becaue this means in a chain lower divison organism also eats the upper level organism.In my opinion it shuld be D. NONE what u say!!!

    1. decomposers – bacteria and protozoa are lower group of organism feeds upoon the dead body of the upper group of organism

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