Prelims · Environment & ecology · 27 questions

Ecology & ecosystems

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 2024 · Q16

Medium

One of the following regions has the world's largest tropical peatland, which holds about three years worth of global carbon emissions from fossil fuels; and the possible destruction of which can exert detrimental effect on the global climate. Which one of the following denotes that region?

Answer & explanation

Answer: (b) Congo Basin

The Cuvette Centrale peatlands of the Congo Basin, spread across the Republic of Congo and the Democratic Republic of the Congo, form the world's largest tropical peatland. They lock away carbon equal to about three years of global greenhouse gas emissions, which would be released if the peat were drained or degraded.

✓ (b) The Congo Basin peat swamp forest stores around 29 billion tonnes of carbon, roughly three years of global emissions; the 2018 Brazzaville Declaration was signed to protect it.
✗ (a) The Amazon has peatlands too, but the single largest tropical peatland complex is the Congo Basin's Cuvette Centrale.
✗ (c) The Kikori Basin is a river basin in Papua New Guinea, rich in forest but not the world's largest tropical peatland.

Remember · Cuvette Centrale, Congo Basin: world's largest tropical peatland, ~29 billion tonnes of carbon ≈ three years of global emissions; Brazzaville Declaration (2018).

Sources

UNEP press release: Historic agreement signed to protect the world's largest tropical peatland ↗ “There is a lot at stake in the protection of these peatlands: the equivalent of three years of global greenhouse gas emissions are stored in the Congo Basin, emissions that could be released if the peatlands are degraded or the natural wetlands drained.”
UNEP story: Critical ecosystems — Congo Basin peatlands ↗ “The peat swamp forest of the Congo Basin stores around 29 billion tons of carbon – approximately equivalent to three years’ worth of global greenhouse gas emissions”

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 · 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 ·

The same topic in Mains

Conservation, pollution & EIAGS 3 syllabus

Read it in NCERT

Class 12 Biology, Chapter 11cited in 2 explanations