UPSC CSE Prelims
Environment & Ecology Previous Year Questions (PYQs)
Solved Previous Year Questions (PYQs) for Environment & Ecology in UPSC CSE Prelims in English & Hindi Medium.
Chapter Breakdown: Scroll →
Consider the following statements with reference to India's response to climate change :
I. India's Long-Term Low Emission Development Strategy (LT-LEDS) is a crucial tool for achieving net-zero emissions by 2070.
II. India's 4th Biennial Update Report (BUR-4) submitted in December, 2024 recorded around 8% decrease in Greenhouse gas emissions in 2020 over 2019.
III. Climate-resilient development necessarily depends on quick and short-term achievement of emission reduction targets.
Which of the following relationships among the above statements is/are correct ?
- Statement I is empirically supported by statement II.
- Statement III contradicts the approach implicit in statement I.
- Statement I and statement III together establish the premise of long-term sustainability.
Select the answer using the code given below :
Detailed Explanation:
This is a tricky "relationship-type" question. Let's understand each base statement first, then check the relationships.
Base Statement I — Correct on its own. LT-LEDS is India's roadmap to reach net-zero by 2070.
Base Statement II — Misleading. Yes, emissions dropped 8% in 2020 vs 2019 — but this was due to COVID-19 lockdowns, not real climate policy success. So it's a temporary effect, not proof that LT-LEDS strategy is working.
Base Statement III — Correct on its own. Real climate resilience needs fast, urgent action now — not just long-term planning.
Now checking the Relationships:
- Relationship 1 — Correct. "Statement I is empirically supported by Statement II" — wait, this says I IS supported by II. But actually the BUR-4 drop was due to COVID, NOT due to LT-LEDS strategy working. So this relationship statement is describing a FALSE claim — and the question asks which relationship statements are correct descriptions of the logical relationship, here pointing out that II does NOT really support I, hence...
Actually — let's simplify: The model answer says relationships 1 and 2 are correct. Relationship 1 says I is supported by II — and the explanation says this is not true (COVID caused the drop, not strategy). So actually relationship statement 1 must be interpreted as a false pairing that the question wants us to identify as the "stated relationship," which the explanation contradicts.
Given the official explanation, the test-makers consider:
- Relationship 2 — Correct: Statement III (need urgent short-term action) contradicts the long-term-only approach of Statement I (LT-LEDS, focused on 2070).
Memory Trick: Long-term plans (2070 target) vs urgent short-term action — these two philosophies are in tension with each other. COVID-linked emission drops are not genuine policy success.
With respect to the Western Hoolock Gibbons, which of the following statements is/are correct?
- A Sanctuary in North-east India is home to this ape species listed as Endangered in the International Union for Conservation of Nature (IUCN) Red List.
- They have specialized brachiation and can easily swing between trees.
- They possess a strong and heavy build like gorillas, yet are remarkably agile tree climbers.
Select the answer using the code given below:
Detailed Explanation:
Statement 1 — Correct. Hollongapar Gibbon Sanctuary in Assam is dedicated to this species. The Western Hoolock Gibbon is listed as Endangered on the IUCN Red List.
Statement 2 — Correct. They move through brachiation — using their long arms to swing quickly from branch to branch. This is their main way of moving through forests.
Statement 3 — Incorrect. Gibbons are "lesser apes" (small apes), NOT like gorillas (great apes). They are small, slender, and lightweight — only 6 to 9 kg. Their light body is exactly WHY they can swing so agilely — a heavy gorilla-like build would make this impossible.
Memory Trick: Gibbons = Light + Long arms = Great swingers. Gorillas = Heavy + Strong = Ground-based. Don't mix them up!
Which of the following best explain(s) the rationale for protecting mangrove ecosystems in the context of climate resilience?
- Mangroves reduce tidal energy and store freshwater, making them ideal sites for paddy cultivation in saline estuarine belts.
- Their salt-sensitive roots filter seawater, making mangroves key to converting coastal land into freshwater aquaculture zones.
- 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:
Detailed Explanation:
Statement 1 — Incorrect. Mangroves do NOT store freshwater and are NOT suited for paddy cultivation. In fact, clearing mangroves to make paddy fields is one of the main reasons mangroves are being destroyed — exactly the opposite of conservation.
Statement 2 — Incorrect. Mangroves are halophytes — meaning their roots are salt-tolerant, not salt-sensitive. They don't convert land into freshwater zones. In fact, clearing mangroves for shrimp farming/aquaculture is a major threat to them.
Statement 3 — Correct. Mangroves act as natural bio-shields:
- Their roots (stilt roots, pneumatophores) reduce tidal energy and protect coasts from storms/cyclones
- They provide livelihood resources — timber, honey, fish breeding — for coastal communities
Memory Trick: Mangroves PROTECT coasts and PROVIDE livelihoods — they are NOT meant to be cleared for farming or freshwater use. Anything suggesting "convert" or "clear mangroves for X" is automatically wrong.
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Which of the following statements in relation to NIRANTAR (National Institute for Research and Application of Natural Resources to Transform, Adapt and Build Resilience), a platform of institutions under the Ministry of Environment, Forest and Climate Change, is/are correct ?
- Ecosystem Survey and Analysis is a vertical under this platform, the lead institute of which is Botanical Survey of India, Kolkata.
- Research and Management of Ecosystem Service is a vertical under this platform, the lead institute of which is Central Zoo Authority, New Delhi.
- Capacity Development Support is a vertical under this platform, the lead institute of which is Indian Institute of Forest Management, Bhopal.
Select the answer using the code given below :
Detailed Explanation:
NIRANTAR is a platform under the Ministry of Environment, Forest and Climate Change with 4 thematic verticals — each led by a specific institute.
Statement 1 — Correct. Ecosystem Survey & Analysis vertical → led by Botanical Survey of India (BSI), Kolkata.
Statement 2 — Incorrect. Research and Management of Ecosystem Service vertical → led by ICFRE, Dehradun — NOT Central Zoo Authority. CZA is just a participating institute, not the lead.
Statement 3 — Correct. Capacity Development Support vertical → led by Indian Institute of Forest Management (IIFM), Bhopal.
Memory Trick:
| Vertical | Lead Institute |
|---|---|
| Ecosystem Survey & Analysis | BSI, Kolkata |
| Research & Mgmt of Ecosystem Service | ICFRE, Dehradun |
| Capacity Development Support | IIFM, Bhopal |
Which of the following statements with regard to the arrival of Amur Falcons at Doyang Lake in Nagaland each year from Mongolia is/are correct?
- It showcases how sustained local conservation efforts can contribute to the arrival and protection of international migratory birds.
- It reflects the global success of advanced tracking technologies that guide migratory birds back to their stopover sites.
- It confirms that Amur Falcons have adapted to permanent residency in India due to favourable habitat changes.
Select the answer using the code given below:
Detailed Explanation:
Statement 1 — Correct. Doyang Lake is a conservation success story. Earlier, falcons were hunted in huge numbers. After efforts by NGOs, the Forest Department, and local communities, hunting stopped completely. Nagaland is now called "Falcon Capital of the World."
Statement 2 — Incorrect. Tracking devices (solar-powered transmitters) only collect data for scientists — they don't guide the birds. Falcons find their way using their own natural instincts, not technology.
Statement 3 — Incorrect. Falcons are not permanent residents of India — they're long-distance migrants. They breed in Siberia/Northern China, then fly to Southern Africa for winter — about 22,000 km journey. Doyang Lake is just a temporary stopover (Oct-Nov) to gain fat reserves before crossing the Arabian Sea.
Consider the following statements about Rhynchostylis retusa (Foxtail orchid) :
- It is an epiphytic orchid.
- The species is endemic to North-east India.
- It is the State flower of Arunachal Pradesh and Assam.
Which of the statements given above is/are correct ?
Detailed Explanation:
Statement 1 — Correct. It's an epiphytic orchid — it grows on tree trunks/branches, using the tree only for support and taking moisture from air. It's not a parasite, doesn't harm the tree.
Statement 2 — Incorrect. Not endemic to North-east India. It's found across Tropical Asia — China, Nepal, Sri Lanka, Bhutan, Myanmar, Thailand, Malaysia, Indonesia, Philippines. Even within India, it grows in Odisha, Andhra Pradesh, Andaman & Nicobar too — not just North-east.
Statement 3 — Correct. It is the State flower of both Assam and Arunachal Pradesh. In Assam, it's called Kopou Phool — culturally important, worn during Bihu dance and weddings.
Memory Trick: "Epiphyte + Endemic" sound similar but mean different things — epiphyte = grows on trees; endemic = found only in one place. Don't confuse the two!
Which one of the following is the first Plan Vivo certified Reducing Emissions from Deforestation and Forest Degradation (REDD+) project in India ?
Detailed Explanation:
This project in Meghalaya is India's first REDD+ project certified under Plan Vivo Standard (a fair-trade-style framework for community forest carbon projects).
Key Facts:
- Location: East Khasi Hills, Meghalaya, near Umiam River
- Managed by: A federation of 10 Khasi tribal kingdoms (called "Synjuk"), covering 60+ communities
- What it does: Protects sacred forest groves (REDD+) and restores degraded forests (Assisted Natural Regeneration)
Why other options are wrong:
- Uttarakhand — only did readiness/pilot work, not the first certified project
- ICFRE-ICIMOD — a broader regional capacity-building program, not a single certified community project
- Sikkim — good conservation work, but not the first
With reference to Madhav National Park, which of the following statements is/are correct ?
- It was declared a Tiger Reserve in India in 2025.
- Sakhya Sagar, which is designated as a Ramsar Site, is situated within this National Park.
- Its area is shared between Madhya Pradesh and Rajasthan.
Select the answer using the code given below :
Detailed Explanation:
Statement 1 is Correct: Madhav National Park was declared India’s 58th Tiger Reserve in March 2025, becoming the 9th Tiger Reserve in Madhya Pradesh.
Statement 2 is Correct: Sakhya Sagar, located within the National Park, was designated as a Ramsar Site in 2022 due to its rich wetland biodiversity and migratory bird habitat.
Statement 3 is Incorrect: Madhav National Park is located entirely in Shivpuri district of Madhya Pradesh. It does not extend into Rajasthan.
Therefore, statements 1 and 2 are correct, making Option B the correct answer.
Madhav National Park
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Located in Shivpuri, Madhya Pradesh, Madhav National Park is part of the Upper Vindhyan Hills ecosystem.
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It gained national importance after being notified as India's 58th Tiger Reserve in 2025 and contains the Ramsar-listed Sakhya Sagar Wetland.
Which organization has enacted the Nature Restoration Law (NRL) to tackle climate change and biodiversity loss?
Detailed Explanation:
Correct Answer: ✅ Option 1 — The European Union
The European Union enacted the Nature Restoration Law (NRL) to restore degraded ecosystems, enhance biodiversity, and strengthen climate resilience. It is one of the world's most ambitious legally binding nature restoration frameworks.
✅ Option A is Correct: The European Union adopted the Nature Restoration Law (2024) with legally binding restoration targets for ecosystems across member states.
❌ Option B is Incorrect: The World Bank provides financing and technical assistance but does not enact such laws.
❌ Option C is Incorrect: The Organisation for Economic Co-operation and Development offers policy recommendations but does not pass binding environmental legislation.
❌ Option D is Incorrect: The Food and Agriculture Organization supports food security and agriculture but does not enact regional laws like the NRL.
Short Notes: Nature Restoration Law (NRL)
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The Nature Restoration Law was adopted by the European Union in 2024.
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It aims to restore degraded terrestrial, freshwater, coastal, and marine ecosystems.
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The law supports the EU's Biodiversity Strategy 2030.
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It contains legally binding restoration targets for member states.
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Restoration of wetlands, forests, grasslands, rivers, and pollinator habitats is a key focus.
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Healthy ecosystems help in carbon sequestration and climate adaptation.
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The NRL is considered a major step in tackling biodiversity loss and climate change simultaneously.
The World Bank warned that India could become one of the first places where wet-bulb temperatures routinely exceed 35 °C. Which of the following statements best reflect(s) the implication of the above‐said report?
I. Peninsular India will most likely suffer from flooding, tropical cyclones and droughts.
II. The survival of animals including humans will be affected as shedding of their body heat through perspiration becomes difficult.
Select the correct answer using the code given below.
Detailed Explanation:
Correct Answer: ✅ Option 3 (Both I and II)
Wet-bulb temperature combines air temperature and humidity. A wet-bulb temperature of 35°C is considered a critical threshold because the human body can no longer cool itself effectively through sweating. The World Bank has warned that parts of India could face dangerous heat stress conditions due to climate change.
✅ Statement I is Correct: Rising temperatures and climate change are expected to increase the frequency and intensity of floods, tropical cyclones, droughts, and other extreme weather events, particularly affecting Peninsular India.
✅ Statement II is Correct: At a wet-bulb temperature of 35°C, sweat cannot evaporate efficiently. As a result, humans and animals are unable to release body heat, creating life-threatening conditions.
Short Notes: Wet-Bulb Temperature
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Wet-bulb temperature combines heat and humidity into a single measure.
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A wet-bulb temperature of 35°C is considered the upper limit of human survivability for prolonged exposure.
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High humidity reduces the effectiveness of evaporative cooling (sweating).
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Climate change is increasing the frequency of extreme heat events.
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India is considered one of the most vulnerable countries to heat stress.
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Wet-bulb temperature is often used to assess human health risks during heatwaves.
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Heat stress can affect agriculture, labor productivity, livestock, and public health.
Artificial way of causing rainfall to reduce air pollution makes use of
Detailed Explanation:
Correct Answer: ✅ Option 1 (Silver iodide and Potassium iodide)
Artificial rainfall, also known as cloud seeding, is a weather modification technique used to induce precipitation. It is sometimes employed to reduce severe air pollution by washing pollutants and particulate matter out of the atmosphere.
✅ Option A is Correct: Silver iodide (AgI) and Potassium iodide (KI) are commonly used cloud-seeding agents. Their crystal structure resembles ice, helping water droplets condense and form rain.
❌ Option B is Incorrect: Silver nitrate is not a standard cloud-seeding material.
❌ Option C is Incorrect: Potassium nitrate is not used for inducing rainfall through cloud seeding.
❌ Option D is Incorrect: Neither silver nitrate nor potassium chloride is used as a conventional cloud-seeding agent.
Short Notes: Cloud Seeding
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Cloud seeding is an artificial technique used to enhance rainfall.
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Common seeding agents include silver iodide (AgI), potassium iodide (KI), and dry ice (solid CO₂).
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These substances act as condensation or ice nuclei.
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Cloud seeding is used to reduce air pollution, increase water availability, and mitigate drought.
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It works only when suitable clouds are already present.
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The technique cannot create clouds from a clear sky.
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Several countries, including India, China, UAE, and the USA, have experimented with cloud seeding.
Consider the following statements:
Statement I: Circular economy reduces the emissions of greenhouse gases.
Statement II: Circular economy reduces the use of raw materials as inputs.
Statement III: Circular economy reduces wastage in the production process.
Which one of the following is correct in respect of the above statements?
Detailed Explanation:
Correct Answer: ✅ Option 1
A Circular Economy aims to keep products, materials, and resources in use for as long as possible through reuse, repair, recycling, and efficient production. This reduces resource extraction, waste generation, and energy consumption, thereby lowering greenhouse gas emissions.
✅ Statement I is Correct: Circular economy helps reduce greenhouse gas (GHG) emissions by minimizing waste, reducing resource extraction, and improving resource efficiency.
✅ Statement II is Correct: It reduces the need for raw materials by promoting reuse, recycling, remanufacturing, and longer product lifecycles.
✅ Statement III is Correct: It minimizes wastage in production processes through efficient design, resource recovery, and sustainable manufacturing practices.
✅ Statement II explains Statement I: Reduced extraction and processing of raw materials lower energy use and associated GHG emissions.
✅ Statement III explains Statement I: Reduced waste generation means lower emissions from manufacturing, disposal, and resource processing.
Short Notes: Circular Economy
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Circular economy follows the principles of Reduce, Reuse, Repair, Refurbish, and Recycle.
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It aims to keep materials in use for the maximum possible time.
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Reduces dependence on virgin raw materials.
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Helps lower greenhouse gas emissions and environmental degradation.
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Minimizes waste sent to landfills and incinerators.
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Supports resource efficiency and sustainable production.
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It is an alternative to the traditional Linear Economy (Take–Make–Dispose) model.
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?
Detailed Explanation:
Correct Answer: ✅ Option 2 (II only)
Most people associate oxygen production with forests, but the oceans are actually the largest source of Earth's oxygen. Marine phytoplankton, algae, and photosynthetic bacteria contribute roughly half of the global oxygen production. Also, atmospheric air contains much higher oxygen concentrations than water.
❌ Statement I is Incorrect: Oceans produce more oxygen than rainforests. Marine phytoplankton are responsible for a major share of global oxygen production.
✅ Statement II is Correct: Marine phytoplankton and photosynthetic bacteria produce about 50% of the world's oxygen through photosynthesis.
❌ Statement III is Incorrect: Atmospheric air contains about 21% oxygen, whereas even well-oxygenated water contains only a small amount of dissolved oxygen. Water does not contain several times more oxygen than air.
Short Notes: Oxygen Cycle and Marine Phytoplankton
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Marine phytoplankton produce nearly 50% of Earth's oxygen.
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Phytoplankton are microscopic photosynthetic organisms found in oceans.
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Oceans are the largest contributor to global oxygen production.
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Atmospheric air contains about 21% oxygen.
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Dissolved oxygen in water is usually measured in mg/L, much lower than oxygen concentration in air.
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Photosynthesis converts CO₂ + Water → Glucose + Oxygen.
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Healthy oceans are essential for maintaining Earth's oxygen balance and climate system.
Consider the following statements:
I. Carbon dioxide (CO₂) emissions in India are less than 0.5 t CO₂/capita.
II. In terms of CO₂ emissions from fuel combustion, India ranks second in Asia-Pacific region.
III. Electricity and heat producers are the largest sources of CO₂ emissions in India.
Which of the statements given above is/are correct?
Detailed Explanation:
Statement I — Incorrect. India's per capita CO₂ emissions are around 1.9–2.0 tonnes, NOT less than 0.5 tonnes. The number given is too low and wrong.
Statement II — Correct. India ranks second in the Asia-Pacific region for CO₂ emissions from fuel combustion — after China (which ranks first).
Statement III — Correct. Electricity and heat production (mostly coal-based) is the largest source of CO₂ emissions in India.
Regarding Peacock tarantula (Gooty tarantula), consider the following statements:
I. It is an omnivorous crustacean.
II. Its natural habitat in India is only limited to some forest areas.
III. In its natural habitat, it is an arboreal species.
Which of the statements given above is/are correct?
Detailed Explanation:
Answer: Option 4 — II and III
Simple Explanation:
Statement I — Incorrect. It is NOT a crustacean — it's a spider (arachnid), specifically a tarantula. Crustaceans (like crabs/shrimp) are a completely different animal group.
Statement II — Correct. Its habitat is restricted to certain forest areas in India, specifically the Eastern Ghats.
Statement III — Correct. It is arboreal — meaning it lives in trees and tree crevices/hollows, not on the ground.
📝 Short Notes: Peacock Tarantula / Gooty Tarantula
| Feature | Detail |
|---|---|
| Scientific Name | Poecilotheria metallica |
| Type | Spider (Arachnid) — NOT a crustacean |
| Habitat | Eastern Ghats, limited forest patches in India (Andhra Pradesh region) |
| Lifestyle | Arboreal — lives in trees/tree hollows |
| Color | Metallic blue with peacock-like patterns |
| Conservation Status | Critically Endangered (IUCN) |
| Significance | One of the rarest and most sought-after tarantulas in the exotic pet trade — major poaching threat |