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.

Asked in 10 of 11 years · most in 2024 (6)

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

Prelims 2024 · Q18

Hard

Consider the following:

1.Carabid beetles
2.Centipedes
3.Flies
4.Termites
5.Wasps

Parasitoid species are found in how many of the above kind of organisms?

Answer & explanation

Answer: (b) Only three

A parasitoid is an insect whose larva lives on or inside a single host and eventually kills it. Almost all parasitoids are wasps and flies, with a smaller number of beetles, including some carabid (ground) beetles. Centipedes are free-living predators and termites are social decomposers, so only three groups qualify.

✓ 1. Some carabid beetles are parasitoids: for example, the larvae of Lebia grandis develop on and kill the pupae of the Colorado potato beetle.
✗ 2. Centipedes are active predators that kill prey with venomous claws; they do not develop inside a host.
✓ 3. Many flies are parasitoids — tachinid and conopid flies, for example, grow inside other insects and kill them.
✗ 4. Termites are social insects that feed on wood and plant matter; none lives as a parasitoid.
✓ 5. Parasitic wasps are the largest parasitoid group: they lay eggs inside other insects and the host dies, which is why they are used in biological pest control.

Remember · Parasitoids kill their host (unlike true parasites). Main groups: wasps (Hymenoptera), flies (Diptera), some beetles. Used widely for biological pest control.

Sources

FAO, Vegetable IPM Regional Training on Biological Control (Thailand DoAE): parasitoids ↗ “Parasitoids are parasitic insects whose larvae feed on the living tissues of an arthropod host. Most are wasps (Hymenoptera), but a few are flies (Diptera).”
USDA Agricultural Research Service (Weber, Saska and Chaboo), Carabid Beetles (Coleoptera: Carabidae) as Parasitoids ↗ “Several genera of carabid beetles are ectoparasitoids as larvae. The parasitoid habit is uncommon in beetles; only eleven beetle families include parasitoid species … Lebia species number over 450 and the genus is cosmopolitan, with 47 in North America. Adults typically seek prey in plant canopies, and all known larvae are ectoparasitoids of chrysomelid beetle pupae”
USDA Agricultural Research Service, AgResearch Magazine: Identifying Tiny Wasps ↗ “And correct identification is critical, as these parasitic wasps lay their eggs inside other insect species, killing the host insect in the process. As a result, these wasps are used extensively, worldwide, to control pest insect populations in agriculture.”

Question and answer: UPSC's official GS Paper I (2024, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2024 · Q19

Easy

Consider the following plants:

1.Groundnut
2.Horse-gram
3.Soybean

How many of the above belong to the pea family?

Answer & explanation

Answer: (c) All three

The pea family is Fabaceae (Leguminosae), the legumes — plants that bear pods and host nitrogen-fixing bacteria in root nodules. Groundnut (Arachis hypogaea), horse-gram (Macrotyloma uniflorum) and soybean (Glycine max) are all legumes, so all three belong to it.

✓ 1. Groundnut (Arachis hypogaea) is an oilseed legume whose pods ripen underground.
✓ 2. Horse-gram (Macrotyloma uniflorum, kulthi) is a drought-hardy pulse legume grown mainly in peninsular India.
✓ 3. Soybean (Glycine max) is a legume with the highest protein content among them, grown for oil and food.

Remember · Pea family = Fabaceae/Leguminosae: pulses (gram, horse-gram, lentil, pea) and oilseed legumes (groundnut, soybean) — all fix nitrogen via root nodules.

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

Sources

NCERT Class 9 · Exploration, Chapter 12 “Kingdom Plantae Phylum Magnoliophyta Class Magnoliopsida Order Fabales Family Fabaceae Genus Pisum Species P. sativum”
FAO, Quality declared seed: technical guidelines for standards and procedures (crop list with botanical families): groundnut and soybean ↗ “Arachis hypogaea L. – Fabaceae – Groundnuts 65 Brassica napus L. – Brassicaceae – Rape 67 Brassica nigra (L.) W. D. J. Koch – Brassicaceae – Mustard 69 Glycine max (L.) Merr. – Fabaceae – Soybean”
ICAR-Indian Institute of Pulses Research, Horsegram ↗ “Horsegram (Macrotyloma uniflorum(L.) Verdc.) is a native to India and is an important food legume crop in the peninsular region.”
FAO AGROVOC multilingual thesaurus, concept: legumes ↗ “Legumes are the fruit or seed of plants of the legume family (such as peas or beans) used for food.”

Question and answer: UPSC's official GS Paper I (2024, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2024 · Q20

Medium Dropped by UPSC

Consider the following statements:

Statement-I: The Indian Flying Fox is placed under the "vermin" category in the Wild Life (Protection) Act, 1972.
Statement-II: The Indian Flying Fox feeds on the blood of other animals.

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

Why UPSC dropped it · explanation

UPSC dropped this question from evaluation in its final answer key.

UPSC dropped this question from evaluation in its final answer key. Statement-II is plainly wrong - the Indian flying fox is a fruit bat that eats fruit and nectar, not blood. Statement-I was also out of date by 2024: the 2022 amendment removed the Act's vermin schedule, so none of the four options fits.

✗ Statement-I The Wild Life (Protection) Amendment Act, 2022 cut the schedules from six to four and removed the vermin schedule, so by 2024 the statement was out of date. Under the amended section 62, the Central Government may declare a Schedule II animal to be vermin by notification, for a stated area and period.
✗ Statement-II The Indian flying fox (Pteropus medius) is one of India's largest fruit bats; it feeds on fruits and nectar and helps pollinate flowers and disperse seeds. Blood-feeding vampire bats live only in the Americas.

Remember · Indian flying fox = fruit bat (fruit, nectar; Nipah virus reservoir). WPA amendment 2022: four schedules, no vermin schedule; the Central Government declares vermin by notification under Section 62.

📘 Read it in NCERT: Class 7 Exploring Society: India and Beyond (Part 1), Ch 8 (practise this chapter)

Sources

Haryana Forest Department: Wild Life (Protection) Act ↗ “Schedules reduce from six to four by reducing the number of schedules for specially protected animals to two, removing the schedule for vermin species, and inserting a new schedule for CITES specimens.”
The Wild Life (Protection) Act, 1972 as amended to 2022, section 62 (India Code; Internet Archive copy) ↗ “to be vermin for any area and for such period as may be specified therein and so long as such notification is in force”
PubMed Central (US NIH): Sequencing the Genome of Indian Flying Fox, Natural Reservoir of Nipah Virus ↗ “Indian fruit bats, flying fox Pteropus medius was identified as an asymptomatic natural host of recently emerged Nipah virus”
NCERT Class 7 · Exploring Society: India and Beyond (Part 1), Chapter 8 “Besides, bats play a critical role in the pollination of flowers and in the dispersal of seeds.”

Question and answer: UPSC's official GS Paper I (2024, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink ·

Prelims 2024 · Q21

Easy

The organisms "Cicada, Froghopper and Pond skater" are:

Answer & explanation

Answer: (c) Insects

All three are insects, and all three belong to Hemiptera, the true bugs. The cicada is the loud 'singing' insect of trees, the froghopper (spittlebug) is a small jumping insect whose young hide in blobs of froth on plants, and the pond skater (water strider) runs across the surface film of still water.

✓ (c) Cicadas and froghoppers (spittlebugs) are grouped in the Auchenorrhyncha, and water striders (pond skaters) in the Heteroptera; both groups are true bugs (order Hemiptera), and true bugs are insects with six legs and a body in three parts.
✗ (b) The pond skater lives on water but never under it: water-repellent hairs on its legs let it stand on the surface, and it breathes air like other insects.
✗ (d) 'Froghopper' is only a name for its frog-like leap; it is a small bug, not a reptile or an amphibian.

Remember · Cicada (Cicadidae), froghopper or spittlebug (Cercopidae) and pond skater or water strider (Gerridae) are all insects of the bug group Hemiptera.

Sources

U.S. National Park Service, Highlights of the Hemiptera BioBlitz: groups of true bugs ↗ “The Auchenorrhyncha (Free-living hemipterans): froghoppers, spittlebugs, cicadas, leafhoppers, planthoppers … The Heteroptera (“Different wings”), which include stink bugs, squash bugs, bed bugs, chinch bugs, milkweed bugs, boxelder bugs, backswimmers, water striders, water boatmen, assassin bugs, and more”
U.S. National Park Service, Species Spotlight: Water Striders (pond skaters) ↗ “Also known as pond skaters or water skippers, striders populate the Gerridae family of insects, of which there are about 1700 species worldwide”
U.S. National Park Service, I Didn't Know That! Emerging Cicadas ↗ “Cicadas belong to the order Hemiptera, or the “true bugs.” Young cicadas, or “nymphs,” live underground, feeding from tree roots until they emerge and molt into adults.”

Question and answer: UPSC's official GS Paper I (2024, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2024 · Q23

Medium

Consider the following pairs:

	Country	Animal found in its natural habitat
1.	Brazil	Indri
2.	Indonesia	Elk
3.	Madagascar	Bonobo

How many of the pairs given above are correctly matched?

Answer & explanation

Answer: (d) None

Every pair is shuffled. The indri is a lemur that lives only in Madagascar, the bonobo is an African ape found in the Congo basin forests of the Democratic Republic of the Congo, and the elk is a large deer of North America and the cold uplands of Asia; none of them occurs wild in the country it is paired with.

✗ 1. The indri (Indri indri), the largest of the lemurs, lives in the eastern rainforests of Madagascar and is Critically Endangered on the IUCN Red List. Lemurs do not occur naturally in South America, so Brazil is wrong.
✗ 2. The elk (wapiti) is a large deer known from North America, where scientists call it Cervus canadensis, and it is also found in parts of Central and East Asia. Tropical Indonesia has no wild elk.
✗ 3. The bonobo, or pygmy chimpanzee, is an African great ape; UNESCO notes it as a threatened species of Salonga National Park in the Democratic Republic of the Congo. Madagascar has no apes.

Remember · Indri = Madagascar (largest lemur). Bonobo = DR Congo only (Salonga NP). Elk/wapiti = North America and Central/East Asia. Madagascar has lemurs but no apes.

Sources

IUCN, Lemurs of Madagascar: A Strategy for Their Conservation 2013-2016 (Ankeniheny-Zahamena Corridor) ↗ “one of the largest continuous rainforests remaining in Madagascar and comprises several management units, from national parks to community-managed sustainable-use reserves. The corridor supports a remarkable 17 species of lemur, including the emblematic and Critically Endangered indri (Indri indri).”
IUCN, Amazing Lemurs (Indri) ↗ “Indris are the largest of the lemurs and are revered in Malagasy culture - legends tell of humans descending from Indri!”
UNESCO World Heritage Centre: Salonga National Park (Democratic Republic of the Congo) ↗ “it constitutes the habitat of numerous threatened species such as the pygmy chimpanzee (or bonobo), the bush elephant and the Congo peacock.”
U.S. National Park Service, Elk, Yellowstone National Park ↗ “The North American elk is considered by some experts to be the same species as the red deer of Europe ( Cervus elaphus ). This is an ongoing taxonomic debate. Currently, most scientists refer to elk in North America as Cervus canadensis .”

Question and answer: UPSC's official GS Paper I (2024, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2024 · Q25

Medium

Consider the following statements:

1.Lions do not have a particular breeding season.
2.Unlike most other big cats, cheetahs do not roar.
3.Unlike male lions, male leopards do not proclaim their territory by scent marking.

Which of the statements given above are correct?

Answer & explanation

Answer: (a) 1 and 2 only

Lions mate at any time of the year, and cheetahs, which are not in the roaring genus Panthera, chirp, purr and growl instead of roaring. Statement 3 fails because male leopards do scent-mark: they hold their territories through boundary scent-marking.

✓ 1. Lions have no fixed breeding season. Females give birth about every 20 months if they raise their cubs, and sooner if they lose them, so lions can breed at any time of year.
✓ 2. The lion and tiger belong to the roaring genus Panthera (NCERT); the cheetah is the only living species of a separate genus, Acinonyx, and does not roar. It purrs, barks, growls, hisses and chirps.
✗ 3. Male leopards maintain their territories through a boundary scent-marking strategy, so they do proclaim territory by scent.

Remember · Roaring cats = genus Panthera (lion, tiger and kin); the cheetah (genus Acinonyx) purrs and chirps, and cannot roar. Lions breed year-round. Male leopards, like lions, scent-mark their territory.

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

Sources

Convention on Migratory Species (CMS, UN), Proposal on Panthera leo: lion biology ↗ “Lions have no fixed breeding season. Females give birth every 20 months if they raise their cubs to maturity, but the interval can be as few as 4-6 weeks if they lose their cubs.”
Smithsonian's National Zoo and Conservation Biology Institute: Cheetah ↗ · reference work “Cheetahs do not roar, but they make sounds including purrs, barks, growls, hisses and chirps that are unlike those of any other cat.”
NCERT Class 9 · Exploration, Chapter 12 “Panthera tigris (tiger) and Panthera leo (lion) under the genus Panthera — the roaring cats (possessing the ability to roar), have similar skull structure”
Verschueren et al., Animal Behaviour 200 (2023) 115-124: Social organization of a solitary carnivore, the leopard, inferred from behavioural interactions at marking sites (peer-reviewed; author copy) ↗ · reference work “Male leopards maintain territories through a boundary scent-marking strategy”

Question and answer: UPSC's official GS Paper I (2024, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink ·

Prelims 2024 · Q28

Easy

Which one of the following shows a unique relationship with an insect that has coevolved with it and that is the only insect that can pollinate this tree?

Answer & explanation

Answer: (a) Fig

Fig trees and fig wasps are the classic case of coevolved mutualism. Many fig species can be pollinated only by one partner wasp species; the female wasp pollinates the fig inflorescence while looking for a place to lay her eggs, and her larvae feed on some of the developing seeds.

✓ (a) NCERT describes a tight one-to-one link between many fig species and their pollinating wasps: a given fig can be pollinated only by its 'partner' wasp, which in turn needs the fig to breed.
✗ (b) Mahua's strong-smelling flowers open at night and are a major attraction for bats, which Down To Earth calls essential for its pollination and seed dispersal; it has no single insect partner.
✗ (d) The red silk cotton tree (Bombax ceiba) is pollinated by generalist birds, not by one coevolved insect.

Remember · Fig–fig wasp: obligate, coevolved, often one-to-one mutualism. The wasp pollinates the fig inflorescence and lays eggs in the fruit; each depends on the other.

📘 Read it in NCERT: Class 12 Biology, Ch 11 (practise this chapter) · Class 12 Biology, Ch 11 (practise this chapter)

Sources

NCERT Class 12 · Biology, Chapter 11 “In many species of fig trees, there is a tight one-to-one relationship with the pollinator species of wasp (Figure 11.4). It means that a given fig species can be pollinated only by its 'partner' wasp species and no other species.”
NCERT Class 12 · Biology, Chapter 11 “plant-animal interactions often involve co-evolution of the mutualists, that is, the evolutions of the flower and its pollinator species are tightly linked with one another.”
Down To Earth: Mahua, the lifeline of Central India's tribal communities ↗ · reference work “Its dull-coloured, strong-smelling flowers, which bloom at night and hang openly, are a major attractant for bats, essential for pollination and seed dispersal.”
Frontiers in Plant Science (2022): Pollen dispersal and multiple paternity in bird-pollinated Bombax ceiba (peer-reviewed) ↗ · reference work “migratory omnivorous (generalist) birds, such as those of Zosteropidae, Sturnidae, and Laniidae families, were the frequent and efficient pollinators of B. ceiba”

Question and answer: UPSC's official GS Paper I (2024, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink ·

Prelims 2024 · Q29

Easy

Consider the following:

1.Butterflies
2.Fish
3.Frogs

How many of the above have poisonous species among them?

Answer & explanation

Answer: (c) All three

Each group includes species that are toxic to eat or touch, a defence that makes predators avoid them. The monarch butterfly stores a poison from the weed its caterpillar eats, many pufferfish carry the deadly nerve toxin tetrodotoxin, and poison frogs secrete toxins through their skin.

✓ 1. The monarch butterfly is distasteful and harmful to birds because of a chemical it takes in as a caterpillar feeding on a poisonous weed.
✓ 2. Pufferfish carry tetrodotoxin, a potent neurotoxin usually concentrated in the ovaries, liver, intestine and skin; it is not destroyed by cooking, and eating badly prepared fish can be fatal.
✓ 3. NCERT notes that some frogs are poisonous and are therefore left alone by predators; the brightly coloured poison dart frogs of Central and South America are the best-known case.

Remember · Poisonous = harmful when eaten or touched (monarch butterfly, pufferfish, poison dart frog); venomous = injects toxin (snake, scorpion). Both are anti-predator defences.

📘 Read it in NCERT: Class 12 Biology, Ch 11 (practise this chapter) · Class 12 Biology, Ch 11 (practise this chapter)

Sources

NCERT Class 12 · Biology, Chapter 11 “Some are poisonous and therefore avoided by the predators. The Monarch butterfly is highly distasteful to its predator (bird) because of a special chemical present in its body.”
NCERT Class 12 · Biology, Chapter 11 “Some species of insects and frogs are cryptically-coloured (camouflaged) to avoid being detected easily by the predator. Some are poisonous and therefore avoided by the predators.”
US CDC Yellow Book, Food Poisoning from Marine Toxins: pufferfish (fugu) poisoning ↗ “Pufferfish poisoning occurs after ingestion of fish containing tetrodotoxin, a potent neurotoxin. Potentially toxic fish are distributed widely worldwide and include pufferfish, porcupine fish, and ocean sunfish. The toxin is usually concentrated in the ovaries, liver, intestine, and skin of the fish.”

Question and answer: UPSC's official GS Paper I (2024, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2024 · Q30

Medium

Consider the following:

1.Cashew
2.Papaya
3.Red sanders

How many of the above trees are actually native to India?

Answer & explanation

Answer: (a) Only one

Only red sanders is Indian by origin: it grows wild in a small tract of the southern Eastern Ghats. Cashew and papaya are both American plants brought to India in the sixteenth and seventeenth centuries, even though India is now a leading grower of both.

✗ 1. Cashew (Anacardium occidentale) is a native of eastern Brazil. The Portuguese introduced it to India in the 16th century, first in Goa, from where it spread along the coasts.
✗ 2. Papaya came from the New World (the Americas) along with the pineapple, tomato, potato and chilli during the Mughal period, as NCERT's history text notes.
✓ 3. Red sanders (Pterocarpus santalinus, 'rakta chandan') is native to southern India, found on dry, rocky hills of the south-eastern peninsula; it is prized and heavily smuggled for its red heartwood.

Remember · Red sanders = native, endemic to the southern Eastern Ghats (mainly Andhra Pradesh). Cashew (Brazil) and papaya (tropical America) were introduced by the Portuguese.

📘 Read it in NCERT: Class 12 Themes in Indian History, Part II, Ch 4 (practise this chapter)

Sources

FAO Ecocrop: Pterocarpus santalinus (red sanders) ↗ “Red sandalwood is native of southern India. In southeastern India, it is found at elevations from 150-1000 m. It usually occur on dry hilly and often rocky ground.”
NCERT Class 12 · Themes in Indian History, Part II, Chapter 4 “Vegetables like tomatoes, potatoes and chillies were introduced from the New World at this time, as were fruits like the pineapple and the papaya.”
Directorate of Cashewnut and Cocoa Development (Ministry of Agriculture, Government of India), Crop history: Cashew ↗ “a native of Eastern Brazil introduced to India just as other commercial crops like Rubber, Coffee, Tea etc. by the Portuguese nearly five centuries back. The first introduction of cashew in India was made in Goa”
APEDA (Ministry of Commerce and Industry, Government of India), Cashew ↗ “one of the most important cash crops introduced to India in 16th century by Portuguese. In India, Cashew was initially introduced in Goa and further expanded to other states.”

Question and answer: UPSC's official GS Paper I (2024, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

The same topic in Mains

Conservation, pollution & EIAGS 3 syllabus

Read it in NCERT

Class 12 Biology, Chapter 11cited in 4 explanations
Class 9 Exploration, Chapter 12cited in 2 explanations
Class 7 Exploring Society: India and Beyond (Part 1), Chapter 8cited in 1 explanation
Class 12 Themes in Indian History, Part II, Chapter 4cited in 1 explanation

Biodiversity, plants & animals

The same topic in Mains

Read it in NCERT

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