UPSC 2021 Prelims ENVIRONMENT Answer Key with Explanation

Question Bank 13 Pages

Union Public Service Commission (Prelims)

Environment

RQG

Contributed by

Runjhun Qabool Gobin

1

UPSC 2021 Prelims
ENVIRONMENT Answer Key with Explanation

1. Which of the following have species that can establish a symbiotic relationship
with other organisms?
1. Cnidarians
2. Fungi
3. Protozoa
Select the correct answer using the code given below.
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
Answer: D
Explanation
● The relationship between cnidarians and dinoflagellate algae is termed as "symbiotic",
because both the animal host and the algae are benefiting from the association. It is a
mutualistic interaction.
● Mycorrhizae are symbiotic relationships that form between fungi and plants. The fungi
colonize the root system of a host plant, providing increased water and nutrient
absorption capabilities while the plant provides the fungus with carbohydrates formed
from photosynthesis.
● Symbiosis in protozoa mostly represents a close mutualistic association between a
protozoan and unicellular symbionts (bacteria, cyanobacteria or/and unicellular algae)
or protozoans and a multicellular organism (ruminants, lower termites, wood-eating
cockroaches, plants). Benefits for a protozoan host can be: extra food supply from
intracellular algae or cyanobacteria, protection from predation and oxygen supply.
https://cals.arizona.edu/azaqua/algaeclass/symbios.htm#:~:text=The%20relationship
%20between%20cnidarians%20and,survive%20without%20the%20dinoflagellate%2
0algae .
https://sciweb.nybg.org/science2/hcol/mycorrhizae.asp.html#:~:text=Mycorrhizae%2
0are%20symbiotic%20relationships%20that,with%20carbohydrates%20formed%20fr
om%20photosynthesis.
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https://www.researchgate.net/publication/306018729_Symbiosis_in_protozoa

2. Why is there a concern about copper smelting plants?
1. They may release lethal quantities of carbon monoxide into the environment.
2. The copper slag can cause the leaching of some heavy metals into the environment.
3. They may release sulphur dioxide as a pollutant.
Select the correct answer using the code given below
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1,2 and 3
Answer: B
Explanation
● The copper smelting plants emit substantial amounts of sulphur dioxide into the
atmosphere and also the copper slag causes leaching of heavy metals like selenium into
the environment. Hence statements 2 and 3 are correct.
● NO proof exists for the release of Lethal quantities of CO into the environment. Hence
statement 1 is incorrect.
https://timesofindia.indiatimes.com/city/chennai/84-gas-leaks-at-sterlite-in-2013-
alone-tn-tells-madras-
hc/articleshow/69881981.cms#:~:text=CHENNAI%3A%20Sterlite's%20copper%20sm
eltering,has%20informed%20Madras%20high%20court.

3. With reference to furnace oil, consider the following statements:
1. It is a product of oil refineries
2. Some industries use it to generate power.
3. Its use causes sulphur emissions into environment
Which of the statements given above are correct?

(a)1 and 2 only
(b)2 and 3 only
(c)1 and 3 only
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(d)1,2 and 3
Answer: D
Explanation
● Furnace oil is the residue fraction obtained from petroleum distillation, which contains
sulphur. Furnace oil contributes to SO2 emission and secondary sulphate formation as
particulate matter (PM). It can also be used to generate power. Hence all the statements
are correct.
https://www.britannica.com/technology/fuel-oil
https://www.hindustantimes.com/mumbai-news/industries-in-critically-polluted-
areas-need-to-reduce-so2-emission-by-90/story-
zrRkO8WRy5ItXcA2yZ2EfI.html#:~:text=Furnace%20oil%20is%20the%20residue,oil
%20use%20in%20Delhi%20NCR.

4. What is blue carbon?
(a) Carbon captured by oceans and coastal ecosystems
(b) Carbon sequestered in forest biomass and agriculture soils
(c) Carbon contained in petroleum and natural gas
(d) Carbon present in atmosphere
Answer: A
Explanation
● Blue carbon is simply the term for carbon captured by the world's ocean and coastal
ecosystems.
https://oceanservice.noaa.gov/facts/bluecarbon.html

5. In nature, which of the following is/are most likely to be found surviving on a surface
without soil?
1. Fern
2. Lichen
3. Moss
4. Mushroom
Select the correct answer using the code given below
(a)1 and 4 only
(b)2 only
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(c)2 and 3
(d)1,3 and 4
Answer: C
Explanation
Lichen does not need soil
https://extension.psu.edu/lichen-in-the-garden

Similarly moss needs only moisture and shade…
https://www.wikihow.life/Grow-Moss

6. Which one of the following is used in preparing a natural mosquito repellent?
(a) Congress grass
(b) Elephant grass
(c) Lemongrass
(d) Nut grass
Answer: C
Lemongrass is a tall herb that is abundantly found in tropical and sub-tropical areas of
Asia, Africa, and Australia. China and India account for the maximum production of
Lemongrass, with an annual production of at least two million pounds. The Lemongrass
plant is known to be an excellent mosquito repellant. According to a study conducted
in 2011, around 95% mosquitos from a specific range of species were either killed or
completely repelled due to the intense odor of lemongrass oil.
https://www.conserve-energy-future.com/is-lemongrass-mosquito-repellent.php

7.Consider the following kinds of organisms:
1. Copepods
2. Cyanobacteria
3. Diatoms
4. Foraminifera
Which of the above are primary producers in the food chains of oceans?
(a) 1 and 2
(b) 2 and 3
(c) 3 and 4
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(d) 1 and 4
Answer: B
Explanation
● An autotroph is an organism that can produce its own food using light, water, carbon
dioxide, or other chemicals. Because autotrophs produce their own food, they are
sometimes called producers. Cyanobacteria and diatoms are primary producers.
● Copepods are a class of small crustaceans that are widespread and naturally abundant in
all aquatic ecosystems as a key link between primary producers and higher predators.
● Foraminifera are heterotrophic, single-celled organisms, members of a phylum or class
of amoeboid protists characterized by streaming granular ectoplasm for catching food
organisms. Many are opportunistic feeders that prey on other autotrophic and
heterotrophic protists.

8.Consider the following animals:
1. Hedgehog
2. Marmot
3. Pangolin
To reduce the chance of being captured by predators, which of the above organisms rolls
up/roll up and protects/protects its/ their vulnerable parts?
(a)1 and 2
(b)2 only
(c)3 only
(d)1 and 3
Answer: D
Explanation
● Hedgehogs have spines which are known as quills, and When they feel threatened, their
quills immediately go up in full force. The hedgehog has muscles located along his sides
that assist in making his spines go up.
● When it is threatened, a pangolin will curl itself into a tight ball, which is impenetrable to
predators. Hence statements 1 and 3 are correct.
● Marmots are relatively large ground squirrels in the genus Marmota, with 15 species
living in Asia, Europe, and North America. These herbivores are active during the summer
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when often found in groups, but are not seen during the winter when they hibernate
underground. They are the heaviest members of the squirrel family.
https://animals.mom.com/hedgehogs-protect-themselves-predators-4232.html
https://www.savepangolins.org/what-is-a-pangolin

9. With reference to the ‘New York Declaration on Forests’, Which of the following
statements are correct?
1. It was first endorsed at the United Nations Climate Summit in 2014.
2. It endorses a global timeline to end the loss of forests.
3. It is a legally binding international declaration.
4. It is endorsed by governments, big companies and indigenous communities
5. India was one of the signatories at its inception
Select the correct answer using the code given below
(a) 1,2 and 4
(b) 1,3 and 5
(c) 3 and 4
(d) 2 and 5
Answer: A
Explanation
● The New York Declaration on Forests is a voluntary and non-legally binding political
declaration spurred by the United Nations Secretary-General’s Climate Summit held in
New York in 2014. Hence statement 3 is incorrect.
● In 2014 at the United Nations Climate Summit, more than 200 governments,
companies, civil society and indigenous organisations signed up to the New York
Declaration on Forests, promising to halve tropical deforestation by 2020 and end it
by 2030. Hence statements 1,2 and 4 are correct.
● India has not signed the NewYork Declaration on Forests. Hence statement 5 is
incorrect.
https://www.climatechangenews.com/2021/10/12/countries-failing-protect-
forests-7-years-new-york-declaration/

10.Magnetite particles, suspected to cause neurodegenerative problems, are
generated as environmental pollutants from which of the following ?
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1. Brakes of motors vehicles
2. Engines of motor vehicles
3. Microwave stoves within homes
4. Power plants
5. Telephone lines
Select the correct answer using the code given below
(a)1,2,3 and 5 only
(b)1,2 and 4 only
(c)3,4 and 5 only
(d)1,2,3,4 and 5
Answer: D
https://www.researchgate.net/publication/327274701_Magnetite_fine_particle_and_na
noparticle_environmental_contamination_from_industrial_uses_of_coal#pf6
https://www.sciencedirect.com/science/article/pii/S0048969720353572#:~:text=Veh
icle%20brake%20systems%20are%20the,airborne%20magnetite%20at%20the%20ro
adside.&text=Magnetite%20concentration%20is%20similar%20in,and%20petrol%2D
engine%20exhaust%20PM.&text=High%20magnetite%20content%20of%20vehicle,a
%20risk%20to%20human%20health.

11. Which one of the following is a filter feeder?
(a) Catfish
(b) Octopus
(c) Oyster
(d) Pelican
Answer: C
Explanation
● Filter feeders are a subgroup of suspension feeding animals that feed by straining
suspended matter and food particles from water, typically by passing the water over a
specialized filtering structure.
● Oysters, clams, and other shellfish are efficient filter feeders that help remove excess
nitrogen from waters by incorporating it into their shells and tissue as they grow.

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12. In which one of the following biogeochemical cycles, the weathering of rocks is
the main source of release of nutrients to enter the cycle?
(a) Carbon cycle
(b) Nitrogen cycle
(c) Phosphorus cycle
(d) Sulphur cycle
Answer: C
Explanation
Phosphorus moves in a cycle through rocks, water, soil and sediments and organisms.
Over time, rain and weathering cause rocks to release phosphate ions and other
minerals. This inorganic phosphate is then distributed in soils and water. Plants take up
inorganic phosphate from the soil.
https://en.wikipedia.org/wiki/Phosphorus_cycle

13. Which of the following are detritivores?
1. Earthworms
2. Jellyfish
3. Millipedes
4. Seahorses
5. Woodlice
Select the correct answer using the code given below.
(a) 1, 2 and 4 only
(b) 2, 3, 4 and 5 only
(c) 1, 3 and 5 only
(d) 1, 2, 3, 4 and 5
Answer: C
Explanation:
● A detritivore is an organism that eats dead or decaying plants or animals as food.
Detritivores include microorganisms such as bacteria and larger organisms such as fungi,
insects, worms, and some crustaceans.
● Earthworms, Millipedes and woodlice are detritivores whereas jellyfish and
seahorses are carnivores.
14. The ‘Common Carbon Metric’, supported by UNEP, has been developed for
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(a) Assessing the carbon footprint of building operations around the world
(b) Enabling commercial farming entities around the world to enter carbon emission
trading
(c) Enabling governments to assess the overall carbon footprint caused by their countries
(d) Assessing the overall carbon footprint caused by the use of fossil fuels by the world in
a unit time.
Answer: A
Explanation
● The Common Carbon Metric is the calculation used to define measurement, reporting,
and verification for GHG emissions associated with the operation of buildings types of
particular climate regions.
https://c2e2.unepdtu.org/wp-content/uploads/sites/3/2016/09/unep-sbci-common-
carbon-metric.pdf

15. How is permaculture farming different from conventional chemical
farming?
1. Permaculture farming discourages monocultural practices but in conventional
chemical farming, monoculture practices are pre- dominant
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.
(a) 1 and 3
(b) 1, 2 and 4
(c) 4 only
(d) 2 and 3
Answer: B
Statement 1: Correct
https://eos.com/blog/monoculture-farming/
http://op.niscair.res.in/index.php/IJTK/article/download/28128/465479185
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Statement 2: Correct
https://www.intechopen.com/chapters/71834
https://www.permaculturenews.org/2005/02/01/use-of-permaculture-under-
salinity-and-drought-conditions/
Statement 4: Correct
https://www.permaculturenews.org/2016/01/22/mulching-with-purpose-and-
precision/

16. With reference to ‘palm oil’, consider the following statements:
1. The palm oil tree is native to Southeast Asia.
2. Palm oil is a raw material for some industries producing lipstick and perfumes.
3. The palm oil can be used to produce biodiesel.
Which of the statements given above are correct.
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1,2 and 3 only
Answer: B
Statement 1 is incorrect: Oil palm trees are native to Africa but were brought to South-
East Asia just over 100 years ago as an ornamental tree crop.
https://www.iucn.org/resources/issues-briefs/palm-oil-and-biodiversity
Statement 2 is Correct: Palm oil in many countries is used as a simple frying oil, but
many other markets make use of both palm and palm kernel oil:
● Consumer retail food and snack manufacturers
● Personal care and cosmetics (lipsticks and perfumes)
● Biofuel and energy
● Animal feed (palm kernel expeller)
● Pharmaceutical
● Industrial
● Foodservice/service industry
https://www.biome.com.au/blog/palm-oil-hidden-in-the-worlds-most-glamourous-
lipsticks/
Statement 3 is Correct: The palm oil can be used to produce biodiesel.
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UPSC 2021 Prelims ENVIRONMENT Answer Key with Explanation

UPSC 2021 Prelims ENVIRONMENT Answer Key with Explanation

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