Here are all 83 Ecology questions asked in UPSC Zoology Optional Paper I from 2004 to 2026, arranged under the 7 topics of the official syllabus. Within each topic the latest questions come first.
Each question ends with a code such as [2024/15m/3b] – the year, the marks, the word limit (where UPSC set one) and the question number in the paper.
2.1] Biosphere and community ecology
32 questions
Green house effect. [2026/10m/150w/5a]
Biome. [2025/10m/150w/5e]
Give an illustrated account of carbon cycle with suitable diagram. [2025/15m/8b]
What is ecological succession? Explain the different types and theories of ecological succession. [2024/20m/6a]
Ecological niche. [2023/10m/150w/5a]
What are ecotones? Explain by giving examples. Also write a note on ‘edge effect’. [2022/10m/150w/5a]
Explain biological, non-biological and industrial fixation of nitrogen. [2022/15m/8b]
Ecological succession. [2021/10m/150w/5d]
Division of biosphere. [2020/10m/150w/5a]
Phosphorus biogeochemical cycle. [2020/10m/150w/5c]
Greenhouse effect and its impact on the atmosphere. [2019/10m/150w/5a]
Biome. [2019/10m/150w/5b]
What is Biogeochemical cycle? Discuss in detail the Nitrogen cycle. [2019/20m/6a]
What is community ecology? Explain different stratification in biotic community. Add a note on species abundance and species diversity. [2019/15m/7b]
What is ecological succession? Give an account of the causes, types and general process of ecological succession in nature. [2018/20m/6a]
What are Ecotones? Are wetlands ecotones? Justify. [2017/10m/150w/5b]
List different human-induced changes in the atmosphere. Describe greenhouse effect and its impact. [2016/10m/150w/5a]
Define ecological succession. Differentiate between primary and secondary succession. Explain various steps involved in the mechanism of ecological succession. [2016/20m/6a]
Enlist the various biomes of the biosphere and discuss the problems and adaptations of the animals of marine and desert biomes. [2016/20m/7a]
What are biogeochemical cycles? Discuss nitrogen cycle indicating the role of atmospheric N-fixation, the role of bacteria and the impact of human activity. [2015/20m/6c]
Distinguish between edge, border and ecotone. Why do edges and ecotones often support a greater diversity of species than the adjoining communities? [2014/10m/150w/5a]
Distinguish between a dominant and keystone species. Add a note on the crucial role played by the keystone species on the community structure and structure of a food web. [2014/20m/7a]
Describe the carbon cycle and discuss its peculiarities. How do human activities interfere with the carbon cycle? [2013/25m/6a]
State briefly what are biomes, ecotones and ecological succession. Give an account of the causes, trends and general process of ecological succession in nature. [2013/25m/7a]
With suitable examples and diagrams, explain the concept of ecological succession. [2012/12m/150w/5c]
Draw a flow diagram of nitrogen cycle, and give accounts of nitrogen fixation, nitrification and denitrification. [2011/15m/150w/5a]
Mention the various steps of sulphur biogeochemical cycle and draw a well labelled diagram. Discuss its significance. [2010/20m/200w/5a]
Describe ecological succession giving suitable examples. [2009/30m/6a]
What is ecological succession? Describe its process in a pod or lake. [2007/20m/200w/5a]
Define the terms Biome and Ecotone and describe major terrestrial biomes. [2006/60m/6]
Discuss Carbon Cycle. Add a note on the greenhouse effect. [2005/20m/200w/5a]
Green house gases and green house effect. [2004/20m/200w/5a]
2.2] Ecosystem
10 questions
Food Web. [2024/10m/150w/5a]
Define food chain. Describe different types of food chain with suitable examples. [2023/15m/6b]
Write a note on ecological pyramids with suitable examples. [2021/15m/6b]
Define ecosystem. Discuss the structure and functions of ecosystem. [2021/20m/8a]
Elaborate the term ‘Ecosystem’ and explain its structural components with examples. Comment on Trophic Dynamics concept. [2017/15m/7b]
Explain adaptations of animals inhabiting fast flowing waters. [2017/15m/8c]
Enlist the various biomes of the biosphere and discuss the problems and adaptations of the animals of marine and desert biomes. [2016/20m/7a]
Define ecosystem. Discuss the dynamics of the ecosystem and the factors influencing it. [2013/25m/6b]
Draw diagrams to differentiate between ecological pyramids based on predator-prey relationship and energy flow in an ecological niche. [2012/12m/150w/5a]
Discuss briefly the degradation of terrestrial ecosystem by human activities. [2011/30m/8a]
2.3] Population ecology
7 questions
Enumerate various population characteristics. Explain the following characteristics in detail: (i) Natality and mortality (ii) Population dispersion. [2026/20m/6a]
Define population. Explain the different characteristics of population. [2024/15m/8b]
Lotka-Volterra model. [2023/10m/150w/5e]
Population dynamics. [2018/10m/150w/5b]
What is meant by distribution? Explain patterns of distribution in natural populations. [2015/15m/6b]
“A population is a self-regulating system.” (Wynne Edwards.) Explain. [2011/30m/6a]
What is meant by the population? Describe various characteristics of a population. Discuss the phenomenon of stabilization of populations. [2004/60m/6]
Preparing for Prelims too?
Our UPSC Prelims Topic-wise PYQ eBook covers every Prelims question with detailed explanations, so you can see exactly where UPSC asks from.
View the BookDownload Free Sample2.4] Biodiversity and conservation
10 questions
Differentiate among alpha, beta and gamma diversity. Explain various factors which threaten the biodiversity. [2026/20m/7a]
Biodiversity hot spots. [2025/10m/150w/5a]
What is meant by biodiversity? Explain various means of in situ conservation of biodiversity. [2022/20m/7a]
Biodiversity hotspots. [2021/10m/150w/5e]
Endemism with reference to India. [2018/10m/150w/5c]
What is meant by Biodiversity? Explain Protected Area Networking w.r.t. their establishment, monitoring and management. [2017/15m/8b]
Define biodiversity hot-spot and mention the criteria of its selection. Write about biodiversity hot-spots of the Indian sub-region giving their salient features. [2015/20m/7c]
Distinguish between in situ and ex situ conservation of animals. Provide suitable examples. [2011/30m/6c]
Define sustainable development. Discuss the principles of sustainable development in the conservation of natural resources. [2010/20m/6a]
Discuss the strategies adopted for conservation of natural resources and biological diversity in India. [2005/60m/6]
2.5] Wildlife of India
4 questions
Red Data Book. [2024/10m/150w/5e]
What is Project Tiger? Discuss the various threats and conservation strategies to protect tigers in India. [2023/15m/7b]
What is meant by Biodiversity? Explain Protected Area Networking w.r.t. their establishment, monitoring and management. [2017/15m/8b]
Enlist five mammalian wildlife endangered species of India. Discuss the present scenario of conservation methods employed for Gir lion. [2010/30m/7b]
2.6] Remote sensing for sustainable development
5 questions
Describe the uses of remote sensing in sustainable development. [2020/15m/6b]
Define remote sensing. Explain how it can be used as an effective tool for sustainable development. [2016/15m/7b]
Define sustainable development. What are the merits of remote sensing in sustainable development? Give examples. [2014/20m/6a]
What are the merits of remote sensing in sustainable development? Give examples. [2012/12m/150w/5b]
Applying remote sensing in studying distribution of animals. [2009/20m/200w/7c]
2.7] Pollution and biodegradation
15 questions
Define air pollution. Explain the types, sources, consequences and control measures of air pollution. [2025/20m/6a]
Differentiate between primary and secondary pollutants. [2022/5m/6b(i)]
Explain primary and secondary treatment of waste water. [2022/10m/6b(ii)]
Give an account of causes, consequences and control of water pollution. Comment on “Ganga action plan”. [2019/20m/8a]
Ozone layer depletion. [2018/10m/150w/5a]
Give an account of sources, impacts and prevention of air pollution. Comment on Montreal and Kyoto protocol also. [2018/20m/7a]
Discuss Thermal Pollution and its preventive measures. [2017/10m/150w/5c]
Discuss environmental degradation with regards to inland water resources. Suggest measures to restore the water quality of our rivers, lakes and reservoirs. [2017/20m/8a]
What is ‘Ganga action plan’? Explain. [2015/10m/150w/5a]
Give an account of causes and consequences of pollution of aquatic resources and the problem of cultural eutrophication. Suggest measures for abatement of water degradation. [2015/15m/7b]
What is ozone layer? Describe the mechanism of degradation of ozone layer and its impact. [2014/15m/8b]
Give the mechanism of ozone degradation by chlorofluorocarbons. [2011/15m/150w/5b]
Environmental biodegradation. [2009/20m/200w/7b]
What is pollution? Describe water pollution, its sources and prevention. [2007/60m/6]
The ozone layer and its impact. [2006/20m/200w/5a]
Strengthen your GS papers
Our UPSC Mains Topic-wise & Year-wise PYQ eBook (2013–2026) maps every GS question to the syllabus, so you know what UPSC asks and how often.
View the BookDownload Free SampleSpotted an error? Tell us.
We classify every PYQ with care, but mistakes can slip in. If a question is in the wrong topic, has a typo, the wrong year, or is missing, let us know. We review every report and update the page.
Report an Error« Previous: Non-Chordata and Chordata | Next: Ethology »
Back to: Zoology Optional PYQs – Topic-wise | Also see: Zoology Optional year-wise question papers
Last updated: 31 October 2026