Consider the following statements: Statement-I. Marsupials are not naturally found in India. Statement-II. Marsupials can thrive only in montane grasslands with no predators. Which one of the following is correct in respect of the above statements?

(a) Both Statement-I and Statement-II are correct and Statement-II is the correct explanation for Statement-I

(b) Both Statement-I and Statement-II are correct and Statement-II is not the correct explanation for Statement-I

(d) Statement-I is incorrect but Statement-II is correct

Prelims · Environment & ecology · 67 questions

Biodiversity, plants & animals

Every UPSC Prelims question on this topic, 2016–2026, newest first. Tap an option to check yourself; the answer and explanation open below it.

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UPSC syllabus: “General issues on Environmental ecology, Bio-diversity and Climate Change - that do not require subject specialization.” See the full syllabus →

Prelims 2023 · Q3

Easy

Consider the following trees:

1.Jackfruit (Artocarpus heterophyllus)
2.Mahua (Madhuca indica)
3.Teak (Tectona grandis)

How many of the above are deciduous trees?

Answer & explanation

Answer: (b) Only two

Teak and mahua are typical trees of India's tropical deciduous (monsoon) forests and shed their leaves in the dry season. Jackfruit keeps its leathery leaves all year and is an evergreen tree, so only two of the three are deciduous.

✗ 1. Jackfruit is an evergreen tree with glossy, leathery leaves; it does not drop its foliage in a dry season.
✓ 2. Mahua is listed among the main species of India's tropical deciduous forests, which shed leaves in the dry months.
✓ 3. Teak is the best-known tree of the tropical deciduous (monsoon) forests of India.

Remember · Tropical deciduous (monsoon) forests: teak, sal, shisham, mahua, amla, semul, kusum, sandalwood. Jackfruit is an evergreen tree.

📘 Read it in NCERT: Class 11 India: Physical Environment, Ch 5 (practise this chapter)

Sources

NCERT Class 11 · India: Physical Environment, Chapter 5 “Teak, sal, shisham, hurra, mahua, amla, semul, kusum, and sandalwood etc. are the main species of these forests.”
Feedipedia (INRAE, CIRAD, AFZ and FAO): Jackfruit (Artocarpus heterophyllus) ↗ · reference work “Artocarpus heterophyllus is an evergreen tree reaching 8-25 m high.”

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2023 · Q12

Easy

Consider the following statements:

Statement-I: Marsupials are not naturally found in India.
Statement-II: Marsupials can thrive only in montane grasslands with no predators.

Which one of the following is correct in respect of the above statements?

Answer & explanation

Answer: (c) Statement-I is correct but Statement-II is incorrect

Pouched mammals (marsupials) occur naturally only in Australia, New Guinea and nearby islands and in the Americas, so none are native to India. But they are not confined to predator-free mountain grasslands: they live in deserts, trees, burrows and even water, often alongside predators.

✓ Statement-I About 200 marsupial species live in Australia, New Guinea and neighbouring islands and about 70 in the Americas, mostly South and Central America. India has no native marsupials.
✗ Statement-II Marsupials occupy many habitats: burrowing, ground-living, tree-living and semi-aquatic species exist. Wallabies, bilbies and the marsupial mole live in the Australian deserts, where NCERT lists dingoes, cats, foxes and snakes among the predators.

Remember · Marsupials (kangaroo, koala, wombat, opossum) are native only to Australasia and the Americas, in habitats from deserts to trees and water; none are native to India.

📘 Read it in NCERT: Class 8 Exploring Society: India and Beyond (Part 2), Ch 1 (practise this chapter)

Sources

Encyclopaedia Britannica, Marsupial ↗ · reference work “Some 200 species of marsupials are found in Australia, New Guinea, and neighbouring islands. Some 70 species live in the Americas, mainly in South and Central America. … Marsupials can be burrowing species, such as wombats ; terrestrial, such as kangaroos ; semiaquatic, such as the water opossum ; or arboreal, such as the koala .”
NCERT Class 8 · Exploring Society: India and Beyond (Part 2), Chapter 1 “The deserts are home to many animals, like reptiles, skinks, wallabies, bilbies, and feral camels. Predators include dingoes, large lizards, cats, foxes, and snakes.”

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink ·

Prelims 2023 · Q13

Easy

‘Invasive Species Specialist Group’ (that develops Global Invasive Species Database) belongs to which one of the following organizations?

Answer & explanation

Answer: (a) The International Union for Conservation of Nature

The Invasive Species Specialist Group (ISSG) is one of the expert groups of IUCN's Species Survival Commission, and it built and runs the Global Invasive Species Database (GISD).

✓ (a) The GISD was developed and is managed by the ISSG of the Species Survival Commission (SSC) of the International Union for Conservation of Nature (IUCN).
✗ (b) UNEP is the UN's environment agency; it does not house the ISSG, which sits inside IUCN's commission structure.
✗ (d) WWF is an independent conservation NGO; the ISSG and its database are part of IUCN, the body that also publishes the Red List.

Remember · ISSG → IUCN Species Survival Commission → runs the Global Invasive Species Database (GISD). IUCN also compiles the Red List.

Sources

IUCN ISSG, Global Invasive Species Database ↗ · reference work “The Global Invasive Species Database was developed and is managed by the Invasive Species Specialist Group (ISSG) of the Species Survival Commission (SSC) of the International Union for Conservation of Nature (IUCN).”

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2023 · Q14

Hard

Consider the following fauna:

1.Lion-tailed Macaque
2.Malabar Civet
3.Sambar Deer

How many of the above are generally nocturnal or most active after sunset?

Answer & explanation

Answer: (a) Only one

UPSC's official answer: (a) · the answer UPSC accepted, and the one that counts in the exam

What we believe is right: (b)

The lion-tailed macaque is a day-active, tree-dwelling monkey, so it is not counted on any reading. The Malabar civet is nocturnal and is the one animal UPSC's key counts.
The sambar is the disputed one. The Kerala Forest and Wildlife Department describes it as 'primarily nocturnal, grazing in open areas at night and seeking refuge in the forests during the day', and Museums Victoria says sambar 'are active at dawn and twilight (crepuscular) and night (nocturnal)'.
The stem asks for animals 'generally nocturnal or most active after sunset'; a deer whose activity peaks at dusk and through the night satisfies it, which makes two, option (b).
UPSC's key counts one; it presumably treats the sambar's daytime grazing in undisturbed forest as making it neither generally nocturnal nor mainly active after sunset.

UPSC's key counts only the Malabar civet; official and museum descriptions of the sambar as nocturnal or crepuscular make it two, giving (b). In the exam, learn each species' activity pattern from an official or IUCN description rather than from general impressions.

Kerala Forest & Wildlife Department: Fauna (Sambar Deer) ↗“Sambar deer are primarily nocturnal, grazing in open areas at night and seeking refuge in the forests during the day to escape the heat and predators.”
Museums Victoria Collections (State of Victoria, Australia): Sambar, Rusa unicolor ↗“They are active at dawn and twilight (crepuscular) and night (nocturnal).”

This box is Minimalist IAS's analysis, with its sources; it does not change UPSC's answer.

UPSC's key counts one animal: the Malabar civet, a secretive night-time carnivore of the Western Ghats. The lion-tailed macaque is a day-active, tree-dwelling monkey. The sambar is not counted: it feeds mainly at dusk and by night but is also seen grazing by day in quiet protected forests, and the key treats this mixed pattern as not 'generally nocturnal'.

✗ 1. The lion-tailed macaque, endemic to the evergreen forests of the Western Ghats, is arboreal and diurnal: its troops feed and move through the canopy by day.
✓ 2. The Malabar civet is nocturnal and so elusive that researchers have to search for it at night; it is among India's most threatened mammals.
✗ 3. The key does not count the sambar. Its activity peaks at dusk and through the night, but in undisturbed forests it is also active by day, and the key treats this crepuscular, mixed pattern as falling short of 'generally nocturnal'.

Remember · Malabar civet: nocturnal, Western Ghats, Critically Endangered. Lion-tailed macaque: diurnal, arboreal, Western Ghats endemic. Sambar: largest Indian deer; most active at dusk and night, also seen by day — not counted as nocturnal in UPSC's key.

Sources

Wildlife Trust of India, Searching for India's most endangered mammal ↗ · reference work “Since Malabar civets are nocturnal, the chances of sighting them at night are high, therefore, I had to keep up the search even at night”
Animal Diversity Web (University of Michigan), Macaca silenus ↗ · reference work “Lion-tailed macaques are arboreal and diurnal. They travel in a family group consisting of 10 to 20 members, but there can be as many as 34 members”
Kerala Forest & Wildlife Department: Fauna (Sambar Deer) ↗ “Sambar deer are primarily nocturnal, grazing in open areas at night and seeking refuge in the forests during the day to escape the heat and predators.”

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink ·

Prelims 2023 · Q15

Easy

Which of the following organisms perform waggle dance for others of their kin to indicate the direction and the distance to a source of their food?

Answer & explanation

Answer: (c) Honeybees

The waggle dance is the honeybee's way of telling hive-mates where food lies. Karl von Frisch decoded it and shared the 1973 Nobel Prize in Physiology or Medicine for this work.

✓ (c) A forager returning from a source more than about 50 m away runs a straight line on the vertical comb while wagging her abdomen; the angle of that run shows the direction relative to the sun, and the vigour of wagging signals distance.
✗ (d) Wasps are social insects too, but they do not use a symbolic dance to point nestmates to food.
✗ (a) Butterflies are solitary foragers and have no dance language for sharing the location of nectar.

Remember · Honeybees: round dance for food close to the hive, waggle dance for food farther away (direction relative to the sun plus distance). Decoded by Karl von Frisch (Nobel 1973).

Sources

NobelPrize.org, Nobel Prize in Physiology or Medicine 1973, press release ↗ “If the source of honey is situated at a distance more than about 50 m from the hive, the returning bee performs a “waggle dance” instead. … The direction of the straight distance informs the hive bees about the direction of the honey source relative to the position of the sun”

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2023 · Q16

Easy

Consider the following statements:

1.Some mushrooms have medicinal properties.
2.Some mushrooms have psychoactive properties.
3.Some mushrooms have insecticidal properties.
4.Some mushrooms have bioluminescent properties.

How many of the above statements are correct?

Answer & explanation

Answer: (d) All four

Mushrooms are the fruiting bodies of a very diverse group of fungi, and each property in the list is shown by at least some species: medicine (reishi, turkey tail), mind-altering chemicals (psilocybin), insect-deterring proteins and compounds, and a natural glow.

✓ 1. NCERT notes that wild edible mushrooms have high nutritional and medicinal values. Medicinal mushrooms such as reishi and turkey tail have been used against infections for centuries in Asia, and for over 30 years have been approved as an add-on to standard cancer treatment in Japan and China.
✓ 2. Psilocybin, a hallucinogen found in certain mushrooms ("magic mushrooms"), alters perception, mood and thought.
✓ 3. Some mushrooms are rarely attacked by insects; studies of their fruit bodies have found insecticidal proteins and antifeedant compounds that are being explored for pest control.
✓ 4. Several gilled mushrooms glow in the dark through a luciferin–luciferase reaction.

Remember · Fungi, including mushrooms, give medicines (reishi), psychoactive psilocybin, insecticidal proteins and bioluminescence (luciferin–luciferase light).

📘 Read it in NCERT: Class 9 Exploration, Ch 12 (practise this chapter)

Sources

NCERT Class 9 · Exploration, Chapter 12 “Wild edible mushrooms are a valuable dietary food with high nutritional and medicinal values.”
US National Cancer Institute, Medicinal Mushrooms (PDQ), Patient Version ↗ “Medicinal mushrooms are mushrooms that are used as medicine. They have been used to treat infection for hundreds of years, mostly in Asia. … For more than 30 years, medicinal mushrooms have been approved as an addition to standard cancer treatments in Japan and China.”
US National Institute on Drug Abuse, Psilocybin (Magic Mushrooms) ↗ “Psilocybin is a chemical in certain types of mushrooms that grow on nearly every continent.”
Berestetskiy & Hu (2021), The Chemical Ecology Approach to Reveal Fungal Metabolites for Arthropod Pest Management, Microorganisms (PMC) ↗ “Mushrooms were found to be promising producers of antifeedant compounds as well as insecticidal proteins.”
Silva-Filho et al. (2023), Eoscyphella luciurceolata gen. and sp. nov., Journal of Fungi (PMC) ↗ “Some species of gilled mushroom are well known and stand out for their natural light emission with a luciferin/luciferase chemical reaction”

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink ·

Prelims 2023 · Q17

Medium

Consider the following statements regarding the Indian squirrels:

1.They build nests by making burrows in the ground.
2.They store their food materials like nuts and seeds in the ground.
3.They are omnivorous.

How many of the above statements are correct?

Answer & explanation

Answer: (b) Only two

The three-striped palm squirrel, a common Indian squirrel, nests in treetops, not in burrows. Like other squirrels it buries nuts and seeds to eat later, and its diet mixes fruit and nuts with insects, larvae and eggs, so it is omnivorous. So statements 2 and 3 are right.

✗ 1. The three-striped palm squirrel builds its nest in treetops out of grass and branches, not in burrows in the ground.
✓ 2. Squirrels bury nuts and seeds and return to some of these caches later; the nuts they forget can grow into trees.
✓ 3. The palm squirrel eats mainly fruit and nuts but also takes insects, larvae, eggs and small birds, so it is omnivorous.

Remember · Indian palm squirrel: tree-nesting (not burrowing), buries nuts and seeds, omnivorous (fruit, nuts, insects, eggs).

Sources

Samson et al. (2020), Three-striped Palm Squirrel roadkills, Mudumalai Tiger Reserve, Journal of Threatened Taxa 12(10) ↗ · reference work “It is an omnivore with a diet based largely on fruit and nuts that also includes eggs, small birds, larvae, and insects … Squirrels mate throughout the year and build nests in treetops using grass and branches.”
Encyclopaedia Britannica, Is It True That Squirrels Forget Where They Bury About Half of Their Food? ↗ · reference work “Squirrels remember where they bury some nuts, but they also forget where they bury others. … Forgotten nuts and acorns grow into trees , so squirrel absentmindedness produces some ecological benefits.”

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink ·

Prelims 2023 · Q18

Easy

Consider the following statements:

1.Some microorganisms can grow in environments with temperature above the boiling point of water.
2.Some microorganisms can grow in environments with temperature below the freezing point of water.
3.Some microorganisms can grow in highly acidic environment with a pH below 3.

How many of the above statements are correct?

Answer & explanation

Answer: (c) All three

Microbes live in places no other life can: hot vents, snow and ice, and strongly acidic sites. Such extremophiles (thermophiles, psychrophiles, acidophiles) make all three statements true.

✓ 1. Hyperthermophiles thrive in hydrothermal vents. Under high pressure, the methanogen Methanopyrus kandleri strain 116 has multiplied at 122 °C in the laboratory, above water's normal boiling point of 100 °C.
✓ 2. Cold-loving microbes (psychrophiles) live in permafrost, sea ice and under thick snow, where they stay active below 0 °C in films of salty, unfrozen water.
✓ 3. Acidophiles grow in highly acidic places such as acid mine drainage and acidic hot springs; some archaea grow best at a pH below 1.

Remember · Extremophiles: thermophiles (up to 122 °C under pressure), psychrophiles (below 0 °C), acidophiles (pH < 3), halophiles (salt).

📘 Read it in NCERT: Class 12 Biology, Ch 8 (practise this chapter)

Sources

NCERT Class 12 · Biology, Chapter 8 “sites such as deep inside the geysers (thermal vents) where the temperature may be as high as 1000C, deep in the soil, under the layers of snow several metres thick, and in highly acidic environments.”
Takai et al. (2008), Cell proliferation at 122°C by a hyperthermophilic methanogen, PNAS 105(31) (PMC) ↗ “Elevated hydrostatic pressures extend the temperature maximum for possible cell proliferation from 116°C at 0.4 MPa to 122°C at 20 MPa, providing the potential for growth even at 122°C under an in situ high pressure.”

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2023 · Q19

Easy

Which one of the following makes a tool with a stick to scrape insects from a hole in a tree or a log of wood?

Answer & explanation

Answer: (b) Orangutan

Among the options, only the orangutan, a great ape, fashions tools from sticks: some wild orangutan populations modify small sticks and use them to probe tree trunks for food such as honey.

✓ (b) Some wild orangutan populations modify small sticks and probe tree trunks with them for food such as honey; Sumatran orangutans also modify sticks to open Neesia fruits.
✗ (d) The sloth bear eats termites and ants, but it digs them out with its long curved claws and sucks them up; it is not known to make tools.
✗ (c) Otters are not known for making stick tools to scrape insects out of wood.

Remember · Orangutan: stick tools to probe tree trunks for food such as honey. Sloth bear: claws and suction to eat termites, no tools.

Sources

Smithsonian's National Zoo, Orangutan ↗ · reference work “Orangutans in some wild populations modify small sticks, which they hold in their lips while probing in tree trunks for food such as honey. … including the modification of sticks by a population of Sumatran orangutans to open Neesia fruits and more efficiently harvest their seeds”
Smithsonian's National Zoo, Sloth bear ↗ · reference work “Sloth bears have shaggy, dusty-black coats; pale, short-haired muzzles; and long, curved claws which they use to excavate termites and ants. … Adult sloth bears are missing their top two front teeth (incisors), which enables them to suck up termites and other insects with ease.”

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink ·

Prelims 2023 · Q69

Medium

'Aerial metagenomics' best refers to which one of the following situations?

Answer & explanation

Answer: (a) Collecting DNA samples from air in a habitat at one go

Aerial metagenomics means collecting DNA from the air in a habitat and sequencing it all together to see which organisms are present. Metagenomics studies the combined genetic material of many organisms in one bulk sample, and here the sample is air.

✓ (a) Air carries tiny particles (bioaerosols) shed by microbes, plants and animals. Sampling that air and sequencing the DNA in it at one go reveals the species around, without catching or disturbing any animal.
✗ (b) This describes genetic study of birds only. Metagenomics covers a whole mixed community of organisms in one sample, not one group such as avian species.
✗ (d) Drones collecting physical plant and animal samples from land and water are a sampling method, not a study of DNA collected from air.

Remember · Metagenomics reads the DNA of a whole community from one bulk sample. In aerial metagenomics that sample is air, giving a snapshot of the species around.

Sources

Metagenomics, Talking Glossary of Genomic and Genetic Terms (National Human Genome Research Institute, US NIH) ↗ “Metagenomics is the study of the structure and function of entire nucleotide sequences isolated and analyzed from all the organisms (typically microbes) in a bulk sample.”
AirDNA sampler: airborne environmental DNA for metagenomic applications (PLoS One, 2023, via PubMed Central) ↗ “metagenomic approach has allowed detection of DNA of plants, invertebrate animals, and vertebrate animals from bioaerosols as a comprehensive mean of diversity analysis in a particular environment”

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink ·

Prelims 2023 · Q79

Medium

Consider the following statements:

1.In India, the Biodiversity Management Committees are key to the realization of the objectives of the Nagoya Protocol.
2.The Biodiversity Management Committees have important functions in determining access and benefit sharing, including the power to levy collection fees on the access of biological resources within its jurisdiction.

Which of the statements given above is/are correct?

Answer & explanation

Answer: (c) Both 1 and 2

Both statements are correct. The Nagoya Protocol is about fair sharing of benefits from genetic resources, and in India the Biological Diversity Act, 2002 gives village-level Biodiversity Management Committees (BMCs) a say in access decisions and the power to levy collection fees.

✓ 1. The Nagoya Protocol aims at fair and equitable sharing of benefits from genetic resources. India's law for this, the Biological Diversity Act, 2002, requires the National Biodiversity Authority and State Biodiversity Boards to consult the local BMC before decisions on using resources in its area, which makes BMCs the local channel for access and benefit sharing.
✓ 2. Section 41(3) of the Act says BMCs may levy charges by way of collection fees from any person accessing or collecting biological resources for commercial purposes from their territorial jurisdiction.

Remember · BMCs are set up by local bodies under Section 41 of the Biological Diversity Act, 2002. They are consulted on access to local biological resources and can levy collection fees, which is India's ground-level route to Nagoya-style benefit sharing.

Sources

The Biological Diversity Act, 2002, section 41 (India Code) ↗ “The Biodiversity Management Committees may levy charges by way of collection fees from any person for accessing or collecting any biological resource for commercial purposes from areas falling within its territorial jurisdiction. … The National Biodiversity Authority and the State Biodiversity Boards shall consult the Biodiversity Management Committees while taking any decision relating to the use of biological resources and knowledge associated with such resources”
Nagoya Protocol on Access and Benefit-sharing, Article 1 (CBD Secretariat) ↗ “The objective of this Protocol is the fair and equitable sharing of the benefits arising from the utilization of genetic resources, including by appropriate access to genetic resources”

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

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