Environment and Ecology: UPSC Previous Year Questions (Prelims)
259 previous year UPSC Prelims Environment and Ecology questions are on this page, from 1996 to 2025, in 10 chapters. Species, Pollution, Environmental Laws and Conventions and Climate Change are the largest, and recent papers lean on statement-pairs about news items: Direct Air Capture, the Nature Restoration Law, PFAS and the Peacock tarantula. Filter by chapter to revise one area, or by year for a single paper.
Explanations state facts as of the year each question was asked; words like “recently” refer to that year.
Showing 31–40 of 259 questions
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UPSC 2023Environment and Ecology · Biodiversity
Q31. 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 a highly acidic environment with a pH below 3. How many of the above statements are correct?
Explanation
Microorganisms are classified into three primary groups on the basis of their preferred range of temperature:
Statement 1 is correct: Hyperthermophiles such as Pyrobolus and Pyrodictium can grow at temperatures exceeding 100°C especially in high-pressure environments like deep-sea hydrothermal vents.
Statement 2 is correct: Psychrophiles such as Colwellia psy-chrerythraea and Pseudomonas syringae can grow at temperatures as low as -10°C and remain metabolically active even at -20°C in environments like Arctic permafrost, deep-sea polar waters, and glacial ice. These microbes produce cryoprotectants such as antifreeze proteins to prevent ice crystal formation in-side their cells.
Statement 3 is correct: Acidophiles such as Ferroplasma acidar-manus and Acidithiobacillus ferrooxidans thrive in environments with pH as low as 0.5, such as acidic hot springs, acid mine drain-ages, and volcanic sulfur pools. These microbes have evolved mechanisms to pump out excess protons (H ions) to maintain internal pH stability. Some acidophiles like Thermoplasma lack a cell wall but possess specialized membrane structures to withstand extreme acidity.
Exam tip:
"Some" = possibility logic, not absolute. If even one species of organism does something, the statement is likely correct. UPSC uses "some" to lower the burden of proof harder to eliminate. Hence all statements are likely correct.
UPSC 2023Environment and Ecology · Biodiversity
Q32. 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?
Explanation
Orangutans are highly intelligent great apes known for their tool-using abilities. They have been observed breaking off small branches and using them as tools to scrape insects from holes in trees or logs. This behavior demonstrates their advanced cognitive skills, problem-solving abilities, and adaptability in foraging. None of the other listed animals.
UPSC 2023Environment and Ecology · Biodiversity
Q33. Consider the following statements: 1. In India, the Biodiversity Management Committees are key to the realisation 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?
Explanation
Statement 1 is correct: In India, Biodiversity Management Committees (BMCs) are established at the local level under the Biological Diversity Act, 2002. The National Biodiversity Authority (NBA) and State Biodiversity Boards (SBBs) work with BMCs to regulate access to biological resources and traditional knowledge, ensuring compliance with the Nagoya Protocol.
Statement 2 is correct: Biological Diversity Act, 2002 empowers BMCs to determine Access and Benefit Sharing (ABS) mechanisms for biological resources found within their jurisdiction. They can levy collection fees on any person or entity accessing biological resources for commercial use.
UPSC 2023Environment and Ecology · Pollution
Q34. Consider the following: 1. Aerosols 2. Foam agents 3. Fire retardants 4. Lubricants In the making of how many of the above are hydrofluorocarbons used?
Explanation
Hydrofluorocarbons (HFCs) are a climate "Super-Pollutant" - Greenhouse gases with hundreds to thousands of times the heat-trapping power of carbon dioxide (CO₂). HFCs are synthetic gases used in air conditioning systems, aerosol propellants, foam- blowing agents, solvents, and flame retardants. These gases were first developed as alternatives to ozone- depleting chemicals, but after their rollout, it was learned that their release to the atmosphere during manufacturing processes and leakage during use, servicing, and retirement/replacement of equipment poses a grave threat to our climate. Lubricants are typically based on oils and synthetic esters, not HFCs.
UPSC 2023Environment and Ecology · Pollution
Q35. Consider the following statements regarding mercury pollution:
Explanation
Statement 1 is correct: Mercury is used in Artisanal Small-Scale Gold Mining (ASGM). The majority of the mercury emissions associated with the ASGM sector come from the burning of mercury-gold amalgam, which is responsible for 38% of all anthropogenic mercury emissions to the atmosphere.
Statement 2 is correct: Mercury is released into the atmosphere via the burning of coal and other fossil fuels. Because coal has far higher mercury content than other fossil fuels, coal-fired power stations frequently produce more mercury pollution than power plants that burn other fossil fuels.
Statement 3 is incorrect: The Occupational Safety and Health Administration (OSHA) considers mercury vapor concentrations above 0.01 mg/m³ hazardous for prolonged exposure, with an acceptable limit of 0.1 mg/m³ based on an 8-hour time-weighted average. Both American Conference of Governmental Industrial Hygienists (ACGIH) and National Institute for Occupational Safety and Health (NIOSH) recommend even lower exposure levels to minimize health risks.
UPSC 2023Environment and Ecology · Pollution
Q36. Consider the following statements: Statement-I: According to the United Nations’ World Water Development Report, 2022’, India extracts more than a quarter of the world’s groundwater withdrawal each year. Statement-II: India needs to extract more than a quarter of the world’s groundwater each year to satisfy the drinking water and sanitation needs of almost 18% of the world’s population living in its Territory. Which one of the following is correct in respect of the above statements?
Explanation
Statement-I is correct: According to the United Nations’ World Water Development Report 2022, India extracts more than a quarter of the world’s groundwater withdrawal each year. This indicates that India has a significant reliance on groundwater resources for various purposes, including irrigation, drinking water, and industrial use. Statement-II is not correct: Approximately 89% of India’s groundwater is utilised for irrigation purposes. The primary portion of the total groundwater extracted in India serves irrigation needs rather than being allocated for drinking and sanitation purposes. Only a small portion of groundwater is utilized for domestic and industrial purposes.
UPSC 2023Environment and Ecology · Climate Change
Q37. Consider the following statements: Statement-I: Carbon markets are likely to be one of the most widespread tools in the fight against climate change. Statement-II: Carbon markets transfer resources from the private sector to the State. Which one of the following is correct in respect of the above statements?
Explanation
Statement I is correct: Carbon markets are trading systems in which carbon credits are sold and bought. Companies or individuals can use carbon markets to compensate for their greenhouse gas emissions by purchasing carbon credits from entities that remove or reduce greenhouse gas emissions. One tradable carbon credit equals one tonne of carbon dioxide or the equivalent amount of a different greenhouse gas reduced, sequestered or avoided. Carbon markets, including compliance and voluntary markets, are widely recognized as effective tools for reducing greenhouse gas emissions. They incentivize emission reductions by allowing entities to trade carbon credits, making them a key mechanism in global climate action.
Statement II is correct: Carbon markets help reduce green-house gas emissions by assigning value to carbon and creating a market for trading carbon credits, which represent the right to emit a certain amount of greenhouse gases. They enable more efficient allocation of emission reduction efforts and facilitate the exchange of allowances between public and private entities, of-ten involving financial transactions. Carbon markets can generate revenue for governments through mechanisms like the sale of emission allowances in compliance markets. However, this is not their primary purpose, as carbon markets primarily facilitate trading between private entities to reduce emissions efficiently.
UPSC 2023Environment and Ecology · Protected Areas for the Biodiversity Conservation
Q38. Consider the following statements: Once the Central Government notifies an area as a ‘Community Reserve’. 1. The Chief Wildlife Warden of the State becomes the governing authority of such forest. 2. Hunting is not allowed in such areas. 3. People of such areas are allowed to collect non-timber forest produce. 4. People of such areas are allowed traditional agricultural practices. How many of the above statements are correct?
Explanation
Statement 1 is incorrect: The State Government will establish a Community Reserve management committee, which will be in charge of conserving, maintaining, and overseeing the community reserve in accordance with Section 36 D of the Wild-life Protection Act (WLPA). The committee will choose a chairman who will serve as the community reserve’s Honorary Wild Life Warden.
Statement 2 is correct: Community Reserves are designated to protect wildlife and biodiversity. Under the Wildlife Protection Act, 1972 hunting is strictly prohibited in all protected areas including Community Reserves. Section 9 of the Act prohibits hunting of wild animals listed in Schedules I, II, III, and IV.
Statement 3 is correct: In a Community Reserve, the collection of non-timber forest produce by the local communities is subject to the specific rules and regulations governing the Community Reserve. It may be regulated or restricted to ensure sustainable use and conservation of resources.
Statement 4 is incorrect: After a forest has been made into a community reserve, people cannot use it for agricultural practices, leave alone jhum cultivation.
UPSC 2023Environment and Ecology · Species
Q39. Invasive Species Specialist Group’ (that develops the Global Invasive Species Database) belongs to which one of the following organisations?
Explanation
The Invasive Species Specialist Group (ISSG) is a global network of scientific and policy experts on invasive species, organised under the auspices of the Species Survival Commission (SSC) of the International Union for Conservation of Nature (IUCN). The ISSG fosters and enables the worldwide exchange of knowledge and information concerning invasive species. It also ensures the linkage between knowledge, practice, and policy to ensure that decisions are based on well-informed insights.
UPSC 2023Environment and Ecology · Species
Q40. 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?
Explanation
Statement 1 is correct: Mushrooms possess antibacterial properties, enhance the immune system, and aid in lowering cholesterol levels. Moreover, they serve as significant reservoirs of bioactive compounds. Consequently, certain mushroom extracts are utilised to support human health and are available in the form of dietary supplements.
Statement 2 is correct: Psychoactive properties refer to substances that influence brain function, resulting in alterations in mood, awareness, cognition, emotions, or behaviour. Psilocybin is a hallucinogenic compound found in specific mushrooms commonly known as magic mushrooms.
Statement 3 is correct: In recent times, there has been a growing discovery of insecticidal compounds within mushrooms.
Statement 4 is correct: Bioluminescence refers to the generation and release of light by living organisms. Panellus stipticus stands out as one of the most luminous bioluminescent mushrooms found on our planet. The newly discovered species, designated as Roridomyces phyllostachydis found in Meghalaya, now joins the ranks of the 97 recognised types of bioluminescent fungi world- wide.
Exam tip:
"Some" = possibility logic, not absolute. If even one species of organism does something, the statement is likely correct. UPSC uses "some" to lower the burden of proof harder to eliminate. Hence all statements are likely correct.
Answer key for these questions
Q
UPSC year
Correct answer
31
2023
(c) All three
32
2023
(b) Orangutan
33
2023
(c) Both 1 and 2
34
2023
(c) Only three
35
2023
(b) Coal-based thermal power plants cause mercury pollution.
36
2023
(c) Statement-I is correct but Statement-II is incorrect
37
2023
(b) Both Statement-I and Statement-II are correct and Statement-II is not the correct explanation for Statement-I
38
2023
(b) Only two
39
2023
(a) The International Union for Conservation of Nature
40
2023
(d) All four
What UPSC has tested in Environment and Ecology
Species questions ask for classification and habitat: which is an insect, a filter feeder, or not a bird, and where an animal is found.
Law and convention questions ask which body or instrument covers what, such as the Wildlife Protection Act’s schedules, the e-Waste Rules and the Ramsar Convention.
Climate questions in 2025 covered Article 6 of the Paris Agreement, COP28, Direct Air Capture and wet-bulb temperatures.
Protected-area questions combine locations with distinctive features, such as the swamp park of Keibul Lamjao and Critical Tiger Habitats.
Frequently asked questions
How many previous year UPSC questions are there on Environment and Ecology?
This page covers 259 previous year UPSC Prelims GS Paper-I questions on Environment and Ecology, asked from 1996 to 2025. Each has the correct answer and an explanation.
Which Environment chapters have the most questions?
Species has the most with 43 questions, followed by Pollution and Environmental Laws, Conventions and Policies with 39 each, and Climate Change with 30. Environmental Organisations and Miscellaneous are the smallest.
How can I revise Environment and Ecology using these questions?
Take a chapter at a time with the Chapter filter, attempt the questions and read the facts UPSC has tested. Revise Species and Protected Areas with a map and a list of national parks at hand.
Are the 2025 Environment questions included?
Yes. The 2025 paper’s Environment questions on activated carbon, cement emissions, COP28, Article 6, Direct Air Capture, the Gooty tarantula, plastics and the Nature Restoration Law are included with full explanations.
