The most important part of any exam is the way of asking questions. UPSC is different and difficult because of its broader and wider area of questions. Each candidate must be perfect and confident while answering the questions.

This exam makes you a person of wisdom and knowledge. You must be aware of the framing of the question paper of the UPSC exam. This exam is regarded as the toughest due to two major factors. Firstly, competency among the high number of candidates and secondly, the questions being asked from around the world. The knowledge within you will bring the confidence in answering.

You must work on gaining the utmost knowledge for this exam. If you are looking for environment questions in UPSC prelims 2020 or environment questions with solutions, you will get everything relevant in this article. Keep reading it to know all the details.

Also Read : 3 Months Preparation Plan for UPSC Prelims: A Step Towards Success

Environment Questions and Answers

The cut-off of the UPSC exam is decided every year by the UPSC board. The two prelims papers are GS paper 1 and GS paper 2. The marks obtained in General Studies Paper – I of the UPSC IAS Exam alone are considered in deciding the cut-off and selecting candidates for the UPSC CSE Mains Exam. You must have all the information about the environment question paper. The General Studies Paper-II of the Civil Services Preliminary Exam is an exam that gives you qualifications. You must get minimum qualifying marks which are 33%. It is also referred to as CSAT. You should get all the necessary documents done before the exam and put your dedication into this exam.

Also Read: UPSC 2021 Topper List: Check Out the Unbelievable Achievements of Candidates

Environment Questions in UPSC Prelims 2020

Q.1. Which of the following statements are correct regarding the general difference between
plant and animal cells?

1. Plant cells have cellulose cell walls whilst animal cells do not
2. Plant cells do not have plasma membrane unlike animal cells which do
3. Mature plant cell has one large vacuole vacuoles

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: (c)

Parameter of Comparison Animal Cell Plant Cell
Cell Shape Irregular or round shape Square of rectangular shape
Cell It is absent It is present
Centrosomes Present Absent
Plastids Absent present
Mode of Nutrition It is Heterotrophic in nature, hence it depends on plants for food It is
autotrophic hence it prepares food on its own.
Both also have plasma membrane. Therefore, statement 2 is not correct. Therefore, the
correct answer is (c).

Q.2. Which of the following are the reasons/factors for exposure to benzene pollution?
Automobile exhaust
Tobacco smoke
Wood burning
Using varnished wooden furniture
Using products made of polyurethane
Select the correct answer using the code given below:

(a) 1, 2 and 3 only
(b) 2 and 4 only
(c) 1, 3 and 4 only
(d) 1, 2, 3, 4 and 5

Answer: (d)

Areas of heavy traffic, gas stations, and areas near industrial sources may also have higher
air levels.
Cigarette smoking and secondhand smoke including wood burning are important sources of
exposure to benzene.
Cigarette smoke accounts for about half of the exposure to benzene in the United States
During fires, polyurethane foams burn rapidly and produce dense smoke, toxic gases and
intense heat.
Carbon monoxide is most common, but smoke also contains benzene, toluene, nitrogen
oxides and hydrogen cyanide.
How benzene works?
• Benzene works by causing cells not to work correctly. For example, it can cause bone
marrow not to produce enough red blood cells, which can lead to anemia. Also, it can
damage the immune system by changing blood levels of antibodies and causing the loss of
white blood cells
• The seriousness of poisoning caused by benzene depends on the amount, route, and
length of time of exposure, as well as the age and preexisting medical condition of the
exposed person Therefore, the correct answer is (d).

Q.3. With reference to Indian elephants, consider the following statements:
1. The leader of an elephant group is a female.
2. The maximum gestation period can be 22 months.
3. An elephant can normally go on calving till the age of 40 years only.
4. Among the States in India, the highest elephant population is in Kerala.

Which of the statements given above is/are correct?
(a) 1 and 2 only
(b) 2 and 4 only
(c) 3 only
(d) 1, 3 and 4 only

Answer: (a)
Elephants live in small family groups led by old females (cows) and Gestation is the longest
of any mammal (18–22 months). So, statement 1 and 2 are correct.
According to the report, released by the Ministry of Environment, Forests and Climate
Change on August 12, Karnataka has the highest number of elephants (6,049), followed by
Assam (5,719) and Kerala (3,054). So, statement 3 and 4 are not correct.
Therefore, the correct answer is (a).

Q.4. Which of the following Protected Areas are located in Cauvery basin?
1. Nagarhole National Park
2. Papikonda National Park
3. Sathyamangalam Tiger Reserve
4. Wayanad Wildlife Sanctuary

Select the correct answer using the code given below:
(a) 1 and 2 only
(b) 3 and 4 only
(c) 1, 3 and 4 only
(d) 1, 2, 3 and 4

Answer: (c)
Nagarhole National Park, also known as Rajiv Gandhi National Park, is in the Cauvery Basin
in India’s Karnataka State.
Papikonda National Park is located near Rajamahendravaram in the Papi Hills in East
Godavari and West Godavari districts of Andhra Pradesh, and covers an area of 1,012.86
km2 (391.07 sq mi).It is an Important Bird and Biodiversity Area and home to some
endangered species of flora and fauna. No part of Papikonda remains outside East and
West Godavari districts after 2014 and after the construction of Polavaram Dam. It means it
is not in cauvery basin.
Therefore, the correct answer is (c).

Q.5. With reference to India’s biodiversity, Ceylon frogmouth, Coppersmith barbet,
Graychinned minivet and White-throated redstart are

(a) Birds
(b) Primates
(c) Reptiles
(d) Amphibians

Answer: (a)
The Sri Lanka frogmouth, Sri Lankan frogmouth or Ceylon frogmouth (Batrachostomus
moniliger) is a small frogmouth found in the Western Ghats of south India and Sri Lanka. It is
a bird that reaches 23 centimetres (9.1 in) in length. Therefore, the correct answer is (a)

Q.6. Which one of the following protected areas is the of the (Barasingha) that thrives well
on hard ground well-known for conservation of a sub-species Indian swamp deer and is
exclusively graminivorous ?

(a) Kanha National Park
(b) Manas National Park
(c) Mudumalai Wildlife Sanctuary
(d) Tal Chhapar Wildlife Sanctuary

Answer: (a)
The revival of BaraSingha, an endangered and endemic cervid, belonging to the cervidae
family, in the Kanha Tiger Reserve is hailed as one of the most successful and inspiring
conservation projects in the world. While Kanha’s name may be synonymous with the tiger, it
is actually the hard ground barasingha that has consistently challenged the professionalism,
including foresightedness and managerial adaptability, of the Kanha management.
Therefore, the correct answer is (a)

Q 7. In the context of recent advances in human reproductive technology, “Pronuclear
Transfer” is used for

(a) fertilization of egg in vitro by the donor sperm
(b) genetic modification of sperm-producing cells
(c) development of stem cells into functional embryos
(d) prevention of mitochondrial diseases in offspring

Answer: (a)
In pronuclear transfer, the mother’s egg is first fertilized with the father’s sperm, producing a
zygote. The pro-nuclei of the egg and sperm are then removed from the zygote and inserted
into a donor egg that has been fertilized and has had its own nucleus removed (a pronucleus
is the nucleus of the egg or sperm at the stage of fertilization prior to nucleus fusion). The
zygote derived from the donor egg is then implanted into the mother’s uterus. It is thus used
in the process of three-parent baby. Three-parent baby, human offspring produced from the
genetic material of one man and two women through the use of assisted reproductive
technologies, specifically mitochondrial manipulation (or replacement) technologies and
three-person in vitro fertilization (IVF). In general, the reproductive technologies used to
produce three-parent babies focus on replacing or otherwise reducing the effects of
mutations that occur in the DNA of cellular organelles known as mitochondria, which reside
in the cell cytoplasm. The various approaches could help women to overcome infertility and
could prevent the transmission to their offspring of potentially debilitating mitochondrial
Therefore, the correct answer is (d).

Q 8. With reference to carbon nanotubes, consider the following statements:
1. They can be used as carriers of drugs and antigens in the human body.
2. They can be made into artificial blood capillaries for an injured part of human body.
3. They can be used in biochemical sensors.
4. Carbon nanotubes are biodegradable.

Which of the statements given above are correct?
(a) 1 and 2 only
(b) 2, 3 and 4 only
(c) 1, 3 and 4 only
(d) 1, 2, 3 and 4

Answer: (d)
Explanation: Carbon nanotubes (CNTs) are allotropes of carbon, made of
graphite and constructed in cylindrical tubes with nanometer in diameter and several
millimeters in length. Their impressive structural, mechanical, and electronic properties are
due to their small size and mass, their strong mechanical potency, and their high electrical
and thermal conductivity. CNTs have been successfully applied in pharmacy and medicine
due to their high surface area that is capable of adsorbing or conjugating with a wide variety
of therapeutic and diagnostic agents (drugs, genes, vaccines, antibodies, biosensors, etc.).
They have been first proven to be an excellent vehicle for drug delivery directly into cells
without metabolism by the body. Then other applications of CNTs have been extensively
performed not only for drug and gene therapies but also for tissue regeneration, biosensor
diagnosis, enantiomer separation of chiral drugs, extraction and analysis of drugs and
pollutants. Hence, statements 1 and 3 are true. CNTs are used in various biomedical
applications like biosensors, diagnostic agents to visualize cancer cells. A multiwalled
carbon nanotube–polyurethane nanocomposite (MWCNT-PU) can be used as vascular graft
or blood capillaries. The disruption of red blood cells by PU and MWCNT-PU has been
studied by measuring the absorbance of free hemoglobin. It has been found that the
MWCNTs with an oxygen-containing functional group are well dispersed in polyurethane
matrix. The number of platelets adhered to the MWCNTPU nanocomposite surface was
remarkably reduced in comparison to that of the PU surface. Investigation of platelet
activation was done by the analysis of conformational changes in glycoprotein measured via
flow cytometry. It is expected that this enabling technology would facilitate the making of
nanodevices using these blood-compatible nanomaterials as building blocks for biomedical
application such as artificial implants, including structural tissue replacements, that is,
artificial blood vessels, or functional devices such as drug delivery matrixes. Hence,
statement 2 is true. Multiple types of microbes including bacteria and fungi have the ability to
degrade carbon nanotubes (CNTs), graphene (GRA), and their derivatives and in the future
more species with this ability will be found. Hence, CNTs are biodegradable. Therefore,
statement 4 is true. Therefore, the correct answer is (d).

Q 9. Consider the following activities:
1. Spraying pesticides on a crop field
2. Inspecting the craters of active volcanoes
3. Collecting breath samples from spouting whales for DNA analysis
4. At the present level of technology, which of the above activities can be successfully
carried out by using drones?

(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
Answer: (d)

Explanation: Drones are already well known to spread pesticides and inspecting volcanoes
remotely. Hence statements 1 and 2 are true. Since 2015 Researchers at the Woods Hole
Oceanographic Institute in Cape Cod have begun using a helicopter-style drone to monitor
humpback whales off the coast, collecting breath samples from their blowholes and taking
aerial pictures. Getting a breath sample from a whale isn’t the easiest task in the world. But
with the help of a hexacopter, scientists are getting the job done. Therefore, the correct
answer is (d).

Q 10. Consider the following statements:
1. Genetic changes can be introduced in the cells that produce eggs or sperms of a
prospective parent.
2. A person’s genome can be edited before birth at the early embryonic stage.
3. Human-induced pluripotent stem cells can be injected into the embryo of a pig.

Which of the statements given above is/are correct?
(a) 1 only
(b) 2 and 3 only
(c) 2 only
(d) 1, 2 and 3

Answer: (d)
Explanation: Gene editing of male and female germ cells An alternative to the
zygote/embryo approach is to perform gene modifications during early gametogenesis. In
this manner, growing immature oocytes or sperm or even pre- cursor cells (primordial germ
cells) can be gene targeted by using the CRISPR/Cas system, producing genetically
corrected mature sperm or oocytes that subsequently can be used for ART. In the male germ
cell line, spermatogonial stem cells (SSC) can be harvested more and more efficiently, and
in vitro culture systems are being developed, also in the human, and optimized for efficient
production of sperm in vitro. So far, animal models have indicated that SSC can be
propagated as clones in culture and then transplanted back into the testis to generate
mature and functional sperm . So a potential strategy would be to select SSC clones that
have undergone correct genomic editing and are free from off-target mutations. These can
then be transplanted to undergo final maturation in vivo. Alternatively, the gene edited SSC
can be directly differentiated in vitro to mature gene-corrected sperm, to be used for IVF.
Still, optimisation of in vitro culture systems is warranted, especially in the human, so that
gene editing technologies can be employed safely and with high efficiency. In the female
germ line, the oocyte is more easily accessible for genetic manipulation, but currently
technical hurdles remain, such as the small number of oocytes that are available . It has
been suggested that oogonia-like stem cells could be harvested, cultured and expanded
followed by culture in vitro to the mature metaphase II stage . However, there is still
controversy over the existence of such oocyte precursor cells in the female and the
efficiency at which mature, developmentally competent oocytes can be derived from them.
Gene editing in zygotes or pre-implantation embryos For germ-line modifications in
experimental settings the genomic editing system is mostly injected into the cytoplasm or
pronuclei of zygotes or into pre-implantation embryos, after which genetic screening is used
to select the embryos with a corrected genomic pattern in the absence of detectable
off-target genetic modifications. Should this turn out to be safe and effective, then similar
applications in the clinic are conceivable. Subsequently, prenatal testing using either cell-free
foetal DNA from the pregnant woman’s blood or one of the more invasive methods (chorionic
villus sampling or amniocentesis), could in theory verify whether or not a foetus shows
molecular or genomic mosaicism. Mosaic embryos arise as a result of inefficient cutting of
the nucleases or inaccurate DNA repair before the embryo has reached the stage of
cleavage. The pre-implantation embryo stage is generally not favoured for genome editing
as it would most likely lead to a mosaic individual and possibly to more unforeseen
detrimental effects. Various studies in different animal models have demonstrated the
feasibility of gene editing in animals at the zygote stage. Hence, statements 1 and 2 are
Hence, statements 1 and 2 are correct. The controversial idea of growing human organs in
host animals has passed through a reality check. Despite recent successes at growing
mouse organs in rats, using the same trick to grow human organs in larger animals such as
pigs is a long way off, new research shows. The researchers tried combining human induced
pluripotent stem cells (reprogrammed adult cells that have regained the characteristics of
embryonic cells) with pig embryos. After they implanted the chimeras into surrogate mothers,
they let the embryos develop for just 3 or 4 weeks, to check whether and where the human
cells were contributing. The researchers implanted more than 2000 human-pig chimeric
embryos into 41 surrogate sows, resulting in 18 pregnancies and 186 embryos a month later.
However, many of the embryos were much smaller than normal and seemed to grow more
slowly, the group reports today in Cell. Hence, so far there has not been success in growing
human organs in pigs. But this experiment shows that human induced pluripotent cells can
be injected into pigs embryo. Hence statement 3 is also correct. Therefore, the correct
answer is (d).

Q 11. If a particular plant species is placed under Schedule VI of The Wildlife Protection Act,
1972, what is the implication?

(a) A licence is required to cultivate that plant
(b) Such a plant cannot be cultivated under any circumstances
(c) It is a Genetically Modified crop plant
(d) Such a plant is invasive and harmful to the ecosystem

Answer: (a)
Explanation: The specified endemic plants in Schedule VI are prohibited from cultivation and
planting. As such a licence is required to cultivate that plant. Therefore, the correct answer is

Q 12. What is/are the advantage/advantages of zero tillage in agriculture?
1. Sowing of wheat is possible without burning the residue of the previous crop
2. Without the need for the nursery of rice saplings, direct planting of paddy seeds in
the wet soil is possible.
3. Carbon sequestration in the soil is possible.

Select the correct answer using the code given below:
(a) 1 and 2 only
(b) 2 and 3 only
(c) 3 only
(d) 1, 2 and 3

Answer: (d)
Explanation: Zero Tillage is the process of agriculture that promotes conservation
agriculture. Here the soil is not tilled and left with at least 30% of cover over soil which may
be previous crop. When wheat seeds are sown in soil using happy seeder, the rice stalks act
as mulch. It not only prevents harmful gases that are released when stubbles are burnt but
also provides enhanced nutrients and improves moisture holding capacity of the soil. The
same is also true for rice when it is directly sown without transplantation. As the soil is not
tilled the remains of previous crop hold carbon and prevent it from entering atmosphere as
carbon di oxide. All statements are correct. Therefore, the correct answer is (d).

Q 13. According to India’s National Policy on Biofuels, which of the following can be used as
raw materials for the production of biofuels?

1. Cassava
2. Damaged wheat grains
3. Groundnut seeds
4. Horse gram
5. Rotten potatoes
6. Sugar beet

Select the correct answer using the code given below:
(a) 1, 2, 5 and 6 only
(b) 1, 3, 4 and 6 only
(c) 2, 3, 4 and 5 only
(d) 1, 2, 3, 4, 5 and 6

Answer: (a)
Explanation: The National Policy on Biofuels expands the scope of raw material
for ethanol production by allowing use of Sugarcane Juice, Sugar containing materials like
Sugar Beet, Sweet Sorghum, Starch containing materials like Corn, Cassava, Damaged
food grains like wheat, broken rice, Rotten Potatoes, unfit for human consumption for
ethanol production. Therefore, the correct answer is (a).

Q 14. Which one of the following statements best describes the term ‘Social Cost of
Carbon’? It is a measure, in monetary value, of the

(a) long-term damage done by a tonne of CO2, emissions in a given year
(b) requirement of fossil fuels for a country to provide goods and services to its citizens,
based on the burning of those fuels
(c) efforts put in by a climate refugee to adapt to live in a new place
(d) contribution of an individual person to the carbon footprint on the planet Earth

Answer: (a)
Explanation: Scientists expect climate change to have increasingly negative consequences
for society, from rising sea levels to more frequent heatwaves. There is broad agreement
that initial, modest benefits – for instance, increased yields for some crops in some regions –
will be outweighed by costs as temperatures rise. One way to get a handle on this question
is through the social cost of carbon (SCC), which tries to add up all the quantifiable costs
and benefits of emitting one additional tonne of CO2, in monetary terms. This value can then
be used to weigh the benefits of reduced warming against the costs of cutting emissions.
Therefore, the correct answer is (a).

Q 15. In the context of India, which of the following is/are considered to be of practice(s) of
eco-friendly agriculture?

1. Crop diversification
2. Legume intensification
3. Tensiometer use
4. Vertical farming

Select the correct answer using the code given below:
(a) 1, 2 and 3 only
(b) 3 only
(c) 4 only
(d) 1, 2, 3 and 4

Answer: (d)
Explanation: Crop diversification refers to the addition of new crops or cropping systems to
agricultural production on a particular farm taking into account the different returns from
value added crops with complementary marketing opportunities. Introducing a greater range
of varieties in a particular agro – ecosystem leads to diversification of agricultural production
which can also increase natural biodiversity, strengthening the ability of the agro-ecosystem
to respond to these stresses. So (1) is correct. The discourse on Legume intensification is
currently framed as ‘Sustainable Intensification’ (SI), and commonly encompasses three
dimensions: (i) increased productivity; (ii) maintenance of ecosystem services; and (iii)
increased resilience to shocks. So (2) is correct. When the water pressure in the tensiometer
is determined to be in equilibrium with the water pressure in the soil, the tensiometer gauge
reading represents the matric potential of the soil. Such tensiometers are used in irrigation
scheduling to help farmers and other irrigation managers to determine when to water. Its
also considered as eco-friendly agriculture as it help control the excessive use of water
distorting the quality of the soil. So (3) is correct. Vertical farming is the practice of growing
crops in vertically stacked layers. It often incorporates controlled-environment agriculture,
which aims to optimize plant growth, and soilless farming techniques such as hydroponics,
aquaponics, and aeroponics. So (4) is correct. Therefore, the correct answer is (d).

Q 16. Consider the following minerals:
1. Bentonite
2. Chromite
3. Kyanite
4. Sillimanite

In India, which of the above is/are officially designated as major minerals?
(a) 1 and 2 only
(b) 4 only
(c) 1 and 3 only
(d) 2, 3 and 4 only

Answer: (d)
Explanation: Major minerals are those specified in the first schedule appended in the MMDR
Act. There is no official definition for “major minerals” in the MMDR Act. Hence, whatever is
not declared as a “minor mineral” may be treated as the major mineral. The central
government has the power to notify “minor minerals” under section 3 (e) of the MMDR Act,
1957. On the other hand, as per Section 15 of the MMDR Act, 1957 State Governments
have complete powers for making Rules for grant of concessions in respect of extraction of
minor minerals and levy and collection of royalty on minor mineralsThus, “Minor Minerals”
are building stones, gravel, ordinary clay, ordinary sand other than sand used for prescribed
purposes etc. Therefore, Chromite, Kyanite and Sillimanite are major minerals, whereas
Bentonite is a minor mineral. Therefore, the correct answer is (d).

Q 17. With reference to Ocean Mean Temperature (OMT), which of the following statements
is/are correct?

1. OMT is measured up to a depth of 26°C isotherm which is 129 meters in the
southwestern Indian Ocean during January — March.
2. OMT collected during January — March can be used in assessing whether the
amount of rainfall in monsoon will be less or more than a certain long-term mean.

Select the correct answer using the code given below:
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2
Answer: (b)
Explanation: • Sea surface temperature (SST) is routinely used for predicting whether the
total amount of rainfall that India receives during the monsoon season will be less or more
than the long-term mean of 887.5 mm. • Now, scientists from Pune’s Indian Institute of
Tropical Meteorology (IITM) find that Ocean Mean Temperature (OMT) has better ability to
predict this than the Sea Surface Temperature. Compared with SST which has 60% success
rate of predicting the Indian summer monsoon, OMT has 80% success rate. • OMT is
analysed by measuring the ocean thermal energy during the period from January to March.
Using OMT data, scientists are able to predict with 80% probability the monsoon of any year.
Hence, statement 2 is correct. • SST is restricted to a few millimetres of the top ocean layer,
whereas OMT which is measured up to a depth of 26 degree C isotherm, is more stable and
consistent, and the spatial spread is also less. The 26 degree C isotherm is seen at depths
varying from 50– 100 metres. During January–March, the mean 26 degree C isotherm depth
in the Southwestern Indian Ocean is 59 metres. Hence, statement 1 is not correct.
Therefore, the correct answer is (b).

Q 18. With reference to India’s Desert National Park, which of the following statements are

1. It is spread over two districts.
2. There is no human habitation inside the Park.
3. It is one of the natural habitats of the Great Indian Bustard.

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: (c)
• The Thar Desert or the Desert National Park (DNP) in north-western India is a unique and
the only habitat of its type in the Indian subcontinent.
• The Aravalli hills mark the eastern-most boundary limit of the Thar desert while the western
limit is defined by the fertile plains of the Indus. The Great Rann of Kutch forms a sharp
boundary in the south while its northern limits are formed by the riparian subHimalayan
• The Desert National Park (DNP) covers an area of 3162 km² of which 1900 km² is in
Jaisalmer district and remaining 1262 km² is in Barmer district of Rajasthan State.
Hence, statement 1 is correct.
• The area falls in the extreme hot and arid region of very low rainfall zone (<100mm) of the
country. DNP was gazetted in the year 1980.
• DNP is a home to Great Indian Bustard (locally called Godawan) along with more than
100 species of birds. Hence, statement 3 is correct.
• The Thar Desert is the most thickly populated desert in the world with an average density
of 83 persons/km² (compared to 7km² of other deserts). However, the human population
within the DNP is low (4-5 persons per km²). There are 73 villages and also settlements or
Dhanis existing within the Park. Hence, statement 2 is not correct.
Therefore, the correct answer is (c).

Q 19. Consider the following statements:
1. 36% of India’s districts are classified as “overexploited” or “critical” by the Central
Ground Water Authority (CGWA).
2. CGWA was formed under the Environment (Protection) Act.
3. India has the largest area under groundwater irrigation in the world.

Which of the statements given above is/are correct?
(a) 1 only
(b) 2 and 3 only
(c) 2 only
(d) 1 and 3 only

Answer: (b)
Explanation: Central Ground Water Authority (CGWA) has been constituted under Section 3
(3) of the Environment (Protection) Act, 1986 to regulate and control development and
management of ground water resources in the country. Hence, statement 2 is correct. India’s
irrigation is mostly groundwater well based. At 39 million hectares (67% of its total irrigation),
India has the world’s largest groundwater well equipped irrigation system (China with 19 mha
is second, USA with 17 mha is third). Hence, statement 3 is correct. According to National
Compilation of Groundwater Resource of India 2017, the average stage of ground water
extraction for the country as a whole works out to be about 63 %. The extraction of ground
water for various uses in different parts of the country is not uniform. Out of the total 6881
assessment units (Blocks/ Mandals/ Talukas/Firkas) in the country, 1186 units in various
States (17%) have been categorized as ‘Over-Exploited’ indicating ground water extraction
exceeding the annually replenishable ground water recharge. In these areas the percentage
of ground water extraction is more than 100 percent. In addition, 313 units (5%) are ‘Critical’,
where the stage of ground water extraction is between 90-100 %. There are 972 semi-critical
units (14%), where the stage of ground water extraction is between 70% and 90% and 4310
assessment units (63%) have been categorized as ‘Safe‘, where the stage of Ground water
extraction is less than 70 %. Apart from this, there are 100 assessment units (1%), which
have been categorized, as ‘Saline’ as major part of the ground water in phreatic aquifers is
brackish or saline. In January 2020, NGT had ordered the Centre to put on hold its new
norms on groundwater use. About 20,000 applications are pending before the CGWA.
Around 800,000 companies fall in overexploited, critical and semi-critical blocks,
representing 36% of 6,881 groundwater assessment units. Hence, statement 1 is not
correct. Therefore, the correct answer is (b).

Q 20. Among the following Tiger Reserves, which one has the largest area under “Critical
Tiger Habitat”?

(a) Corbett
(b) Ranthambore
(c) Nagarjunsagar-Srisailam
(d) Sunderbans

Answer: (c)
Tiger Reserve Area of the Core / Critical Tiger Habitat (in sq. Km)
Corbett 821.99
Ranthambore 1113.364
Nagarjunsagar-Srisailam 2595.72
Sunderbans 1699.62
Therefore, the correct answer is (c).

Q 21. Which of the following are the most likely places to find the musk deer in its natural

1. Askot Wildlife Sanctuary
2. Gangotri National Park
3. Kishanpur Wildlife Sanctuary
4. Manas National Park

Select the correct answer using the code given below:
(a) 1 and 2 only
(b) 2 and 3 only
(c) 3 and 4 only
(d) 1 and 4 only

Answer: (a)
The white-bellied musk deer or Himalayan musk deer (Moschus leucogaster) is a musk deer
species occurring in the Himalayas of Nepal, Bhutan, India, Pakistan and China. It is found
in Askot Wildlife Sanctuary and Gangotri National Park located in the Himalayan regions. It
is listed as endangered on the IUCN Red List because of overexploitation resulting in a
probable serious population decline. So, (1) and (2) are correct. The Kishanpur Wildlife
Sanctuary is a part of the Dudhwa Tiger reserve near Mailani in Uttar Pradesh, India and
Musk deer is not found here. So (3) is not correct. Manas National Park or Manas Wildlife
Sanctuary is a national park, UNESCO Natural World Heritage site, a Project Tiger reserve,
an elephant reserve and a biosphere reserve in Assam, India. The park is known for its rare
and endangered endemic wildlife such as the Assam roofed turtle, hispid hare, golden langur
and pygmy hog. Manas is famous for its population of the wild water buffalo. So (4) is not
correct. Therefore, the correct answer is (a).

Q 22. In rural road construction, the use of which of the following is preferred for ensuring
environmental sustainability or to reduce carbon footprint?
1. Copper slag
2. Cold mix asphalt technology
3. Geotextiles
4. Hot mix asphalt technology
5. Portland cement

Select the correct answer using the code given below:
(a) 1, 2 and 3 only
(b) 2, 3 and 4 only
(c) 4 and 5 only
(d) 1 and 5 only

Answer: (a)
Explanation: • The usage of Copper slag reduces the usage of primary materials as well as
reduces the construction depth which in turn reduces energy demand in building. So, (1) is
correct. • Cold asphalt mix is produced by mixing unheated mineral aggregate with either
emulsified bitumen or foamed bitumen. Unlike hot mix asphalt (HMA), cold asphalt mix does
not require any heating of aggregate which makes it economical and relatively pollution-free
(no objectionable fumes or odours). So, (2) is correct and (4) is not correct. • Geotextiles
reinforces the soil by adding tensile strength to i. It is used as a rapid de watering layer in the
roadbed. So, (3) is correct. • Portland cement production needs energy and can impact the
environment. So, (5) is not correct. Therefore, the correct answer is (a).

Q 23. Steel slag can be the material for which of the following?
1. Construction of base road
2. Improvement of agricultural soil
3. Production of cement

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: Steel slag, a by-product of steel making, is produced during the separation of
the molten steel from impurities in steel-making furnaces. The slag occurs as a molten liquid
melt and is a complex solution of silicates and oxides that solidifies upon cooling. It is used
in various activities such as in road construction, these are the preferred aggregates as they
harden well, enabling a thinner layer of pavement than what can be achieved with crushed
stone aggregates. Slag is also very hardy, resistant to both weather and wear. So, statement
1 is correct. Benefits of using steel slag for crops: Slag application favors the increase of pH
and the availability of nutrients such as Ca, Mg, and Si in the soil, which leads to the
increase in the absorption of these elements by the plant, favoring the growth and yield of
the crops. So, statement 2 is correct. Steel-slag can be used to produce energy-saving
cement by co-grinding with OPC clinker and blast furnace slag. It can replace Portland
cement in various applications and is especially suitable for projects where a low heat of
hydration is required. So, statement 3 is correct. Therefore, the correct answer is (d).

Q 24. Consider the following statements:
1. Coal ash contains arsenic, lead and mercury.
2. Coal-fired power plants release sulphur dioxide and oxides of nitrogen into the
3. High ash content is observed in Indian coal.

Which of the statements given above is/are correct?
(a) 1 only
(b) 2 and 3 only
(c) 3 only
(d) 1, 2 and 3

Answer: (d)
Explanation: Coal ash contains contaminants like mercury, cadmium and arsenic. Without
proper management, these contaminants can pollute waterways, ground water, drinking
water, and the air. The burning of coal releases many pollutants – oxides of nitrogen (NOx)
and sulfur (SOx) – and particulate matter. They also emit greenhouse gases, such as carbon
dioxide (CO2) and methane (CH4), which are known to contribute to global warming and
climate change. Coal India Limited announced that ash content of coal produced in the
country is generally 25 to 45 % whereas average ash content of imported coal varies from
10 to 20 %. Indian Coal has comparatively higher ash content than imported coal due to drift
theory of formation of coal deposits in India. Therefore, all statements are correct. Therefore,
the correct answer is (d).

Q 25. What is the use of biochar in farming?
1. ‘Biochar can be used as a part of the growing medium in vertical farming.
2. When biochar is a part of the growing medium, it promotes the growth of nitrogen
fixing microorganisms.
3. When biochar is a part of the growing- medium, it enables the growing medium to
retain water for longer time.

Which of the statements given above is/are correct?
(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Answer: (d)
Explanation: Biochar has the potential to produce farm-based renewable energy in an
eco-friendly way. Specifically, the quality of biochar depends on several factors, such as the
type of soil, metal, and the raw material used for carbonization, the pyrolysis conditions, and
the amount of biochar applied to the soil. In addition, the biochar amendment to the soil
proved to be beneficial to improve soil quality and retain nutrients, thereby enhancing plant
growth. Since biochar contains organic matter and nutrients, its addition increased soil pH,
electric conductivity (EC), organic carbon (C), total nitrogen (TN), available phosphorus (P),
and the cation-exchange capacity (CEC). Earlier, reported that the biochar application
affected the toxicity, transport, and fate of various heavy metals in the soil due to improved
soil absorption capacity. The presence of plant nutrients and ash in the biochar and its large
surface area, porous nature, and the ability to act as a medium for microorganisms have
been identified as the main reasons for the improvement in soil properties and increase in
the absorption of nutrients by plants in soils treated with biochar. Biochar application
decreased the tensile strength of soil cores, indicating that the use of biochar can reduce the
risk of soil compaction. A lot has already been discussed on the benefits of inoculation of
rhizobacteria in soil, but the addition of biochar can also provide more nutrients to the soil,
thus benefiting the agricultural crops. The mixing of the plant growth-promoting
microorganisms with biochar was referred to as the best combination for growth and yield of
French beans Therefore, all statements are correct. Therefore, the correct answer is (d).

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Environment Questions in UPSC Prelims 2020: Here’re the Prelims Questions with Detailed Answers
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Environment Questions in UPSC Prelims 2020: Here’re the Prelims Questions with Detailed Answers
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Shilpa is a professional web content writer and is in deep love with travelling. She completed her mass communication degree and is now dedicatedly playing with words to guide her readers to get the best for themselves. Developing educational content for UPSC, IELTS aspirants from breakthrough research work is her forte. Strongly driven by her zodiac sign Sagittarius, Shilpa loves to live her life on her own notes and completely agrees with the idea of ‘live and let live. Apart from writing and travelling, most of the time she can be seen in the avatar of 'hooman' mom to her pets and street dogs or else you can also catch her wearing the toque blanche and creating magic in the kitchen on weekends.

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