Ecology & Ecosystems PYQs

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1. Prelims 2026Q33Ecology & Ecosystems

   Which of the following best explain(s) the rationale for protecting mangrove ecosystems in the context of climate resilience ?

   1.Mangroves reduce tidal energy and store freshwater, making them ideal sites for paddy cultivation in saline estuarine belts.

   2.Their salt-sensitive roots filter seawater, making mangroves key to converting coastal land into freshwater aquaculture zones.

   3.By withstanding tidal surges and offering biomass resources, mangroves function both as natural bio-shields and livelihood bases for rural communities.

   Select the answer using the code given below :

   a1 onlyb1 and 2c2 and 3d3 only
2. Prelims 2025Q40Ecology & Ecosystems

   With reference to the planet Earth, consider the following statements :

   I.Rain forests produce more oxygen than that produced by oceans.

   II.Marine phytoplankton and photosynthetic bacteria produce about 50% of world's oxygen.

   III.Well-oxygenated surface water contains several folds higher oxygen than that in atmospheric air.

   Which of the statements given above is/are correct?

   aI and IIbII onlycI and IIIdNone of the above statements is correct
3. Prelims 2024Q16Ecology & Ecosystems

   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 ?

   aAmazon BasinbCongo BasincKikori BasindRio de la Plata Basin
4. Prelims 2024Q28Ecology & Ecosystems

   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 ?

   aFigbMahuacSandalwooddSilk cotton
5. Prelims 2022Q43Ecology & Ecosystems

   “If rainforests and tropical forests are the lungs of the Earth, then surely wetlands function as its kidneys.” Which one of the following functions of wetlands best reflects the above statement ?

   aThe water cycle in wetlands involves surface runoff, subsoil percolation and evaporation.bAlgae form the nutrient base upon which fish, crustaceans, molluscs, birds, reptiles and mammals thrive.cWetlands play a vital role in maintaining sedimentation balance and soil stabilization.dAquatic plants absorb heavy metals and excess nutrients.
6. Prelims 2022Q49Ecology & Ecosystems

   “Biorock technology” is talked about in which one of the following situations ?

   aRestoration of damaged coral reefsbDevelopment of building materials using plant residuescIdentification of areas for exploration/extraction of shale gasdProviding salt licks for wild animals in forests/protected areas
7. Prelims 2021Q20Ecology & Ecosystems

   In the 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.

   a1 and 4 onlyb2 onlyc2 and 3d1, 3 and 4
8. Prelims 2021Q22Ecology & Ecosystems

   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?

   a1 and 2b2 and 3c3 and 4d1 and 4
9. Prelims 2021Q26Ecology & Ecosystems

   Which one of the following is a filter feeder?

   aCatfishbOctopuscOysterdPelican
10. Prelims 2021Q27Ecology & Ecosystems

    In case of which one of the following biogeochemical cycles, the weathering of rocks is the main source of release of nutrient to enter the cycle?

    aCarbon cyclebNitrogen cyclecPhosphorus cycledSulphur cycle
11. Prelims 2021Q28Ecology & Ecosystems

    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.

    a1, 2 and 4 onlyb2, 3, 4 and 5 onlyc1, 3 and 5 onlyd1, 2, 3, 4 and 5
12. Prelims 2021Q30Ecology & Ecosystems

    Which of the following have species that can establish symbiotic relationship with other organisms?

    1.Cnidarians

    2.Fungi

    3.Protozoa

    Select the correct answer using the code given below.

    a1 and 2 onlyb2 and 3 onlyc1 and 3 onlyd1, 2 and 3
13. Prelims 2018Q2Ecology & Ecosystems

    Which of the following leaf modifications occur(s) in the desert areas to inhibit water loss ?

    1.Hard and waxy leaves

    2.Tiny leaves

    3.Thorns instead of leaves

    Select the correct answer using the code given below :

    a2 and 3 onlyb2 onlyc3 onlyd1, 2 and 3
14. Prelims 2018Q87Ecology & Ecosystems

    Consider the following statements :

    1.Most of the world's coral reefs are in tropical waters.

    2.More than one-third of the world's coral reefs are located in the territories of Australia, Indonesia and Philippines.

    3.Coral reefs host far more number of animal phyla than those hosted by tropical rainforests.

    Which of the statements given above is/are correct ?

    a1 and 2 onlyb3 onlyc1 and 3 onlyd1, 2 and 3
15. Prelims 2017Q21Ecology & Ecosystems

    Due to some reasons, if there is a huge fall in the population of species of butterflies, what could be its likely consequence/consequences ?

    1.Pollination of some plants could be adversely affected.

    2.There could be a drastic increase in the fungal infections of some cultivated plants.

    3.It could lead to a fall in the population of some species of wasps, spiders and birds.

    Select the correct answer using the code given below :

    a1 onlyb2 and 3 onlyc1 and 3 onlyd1, 2 and 3
16. Prelims 2015Q84Ecology & Ecosystems

    Which one of the following is the best description of the term 'ecosystem'?

    aA community of organisms interacting with one anotherbThat part of the Earth which is inhabited by living organismscA community of organisms together with the environment in which they livedThe flora and fauna of a geographical area
17. Prelims 2014Q19Ecology & Ecosystems

    Which of the following adds/add carbon dioxide to the carbon cycle on the planet Earth?

    1.Volcanic action

    2.Respiration

    3.Photosynthesis

    4.Decay of organic matter

    Select the correct answer using the code given below.

    a1 and 3 onlyb2 onlyc1, 2 and 4 onlyd1, 2, 3 and 4
18. Prelims 2014Q22Ecology & Ecosystems

    Lichens, which are capable of initiating ecological succession even on a bare rock, are actually a symbiotic association of

    aalgae and bacteriabalgae and fungicbacteria and fungidfungi and mosses
19. Prelims 2014Q41Ecology & Ecosystems

    Which of the following have coral reefs?

    1.Andaman and Nicobar Islands

    2.Gulf of Kachchh

    3.Gulf of Mannar

    4.Sunderbans

    Select the correct answer using the code given below.

    a1, 2 and 3 onlyb2 and 4 onlyc1 and 3 onlyd1, 2, 3 and 4
20. Prelims 2014Q80Ecology & Ecosystems

    Which one of the following is the correct sequence of a food chain?

    aDiatoms–Crustaceans–HerringsbCrustaceans–Diatoms–HerringscDiatoms–Herrings–CrustaceansdCrustaceans–Herrings–Diatoms
21. Prelims 2013Q22Ecology & Ecosystems

    In the grasslands, trees do not replace the grasses as a part of an ecological succession because of

    ainsects and fungiblimited sunlight and paucity of nutrientscwater limits and firedNone of the above
22. Prelims 2013Q23Ecology & Ecosystems

    Which one of the following is the correct sequence of ecosystems in the order of decreasing productivity?

    aOceans, lakes, grasslands, mangrovesbMangroves, oceans, grasslands, lakescMangroves, grasslands, lakes, oceansdOceans, mangroves, lakes, grasslands
23. Prelims 2013Q31Ecology & Ecosystems

    With reference to food chains in ecosystems, consider the following statements:

    1.A food chain illustrates the order in which a chain of organisms feed upon each other.

    2.Food chains are found within the populations of a species.

    3.A food chain illustrates the numbers of each organism which are eaten by others.

    Which of the statements given above is/are correct?

    a1 onlyb1 and 2 onlyc1, 2 and 3dNone
24. Prelims 2013Q34Ecology & EcosystemsAnswer disputed

    Which of the following adds/add nitrogen to the soil?

    1.Excretion of urea by animals

    2.Burning of coal by man

    3.Death of vegetation

    Select the correct answer using the codes given below.

    a1 onlyb2 and 3 onlyc1 and 3 onlyd1, 2 and 3
25. Prelims 2013Q48Ecology & Ecosystems

    Which one of the following terms describes not only the physical space occupied by an organism, but also its functional role in the community of organisms?

    aEcotonebEcological nichecHabitatdHome range
26. Prelims 2013Q53Ecology & Ecosystems

    With reference to the food chains in ecosystems, which of the following kinds of organism is/are known as decomposer organism/organisms?

    1.Virus

    2.Fungi

    3.Bacteria

    Select the correct answer using the codes given below.

    a1 onlyb2 and 3 onlyc1 and 3 onlyd1, 2 and 3
27. Prelims 2013Q97Ecology & Ecosystems

    Mycorrhizal biotechnology has been used in rehabilitating degraded sites because mycorrhiza enables the plants to

    1.Resist drought and increase absorptive area

    2.Tolerate extremes of pH

    3.Resist disease infestation

    Select the correct answer using the codes given below:

    a1 onlyb2 and 3 onlyc1 and 3 onlyd1, 2 and 3
28. Prelims 2012Q91Ecology & Ecosystems

    Consider the following kinds of organisms :

    1.Bat

    2.Bee

    3.Bird

    Which of the above is/are pollinating agent/agents?

    a1 and 2 onlyb2 onlyc1 and 3 onlyd1, 2 and 3
29. Prelims 2012Q94Ecology & Ecosystems

    The Millennium Ecosystem Assessment describes the following major categories of ecosystem services—provisioning, supporting, regulating, preserving and cultural. Which one of the following is supporting service?

    aProduction of food and waterbControl of climate and diseasecNutrient cycling and crop pollinationdMaintenance of diversity
30. Prelims 2012Q99Ecology & Ecosystems

    What would happen if phytoplankton of an ocean is completely destroyed for some reason?

    1.The ocean as a carbon sink would be adversely affected.

    2.The food chains in the ocean would be adversely affected.

    3.The density of ocean water would drastically decrease.

    Select the correct answer using the codes given below :

    a1 and 2 onlyb2 onlyc3 onlyd1, 2 and 3