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UPPCS Prelims PYQ · 2019–2023
78 questions organized across 9 themes — from ecosystem basics to current affairs. Click any question to reveal the explanation.
Ecosystem types, food chains, ecological niches, succession, and foundational ecology concepts.
Example of Lotic ecosystem is–
Given below are two statements one is labelled as Assertion (A) and the other as Reason (R). Assertion (A) : Phytoplankton grow in abundance in the limnetic zone. Reason (R): Limnetic zone is open water zone. Select the correct answer from the code given below: Code:
With reference to ecological niche, which of the following statements is/are correct? 1. It represents the range of conditions that it can tolerate the resources it utilizes and its functional role in ecological system. 2. Each species has a distinct niche. Select the correct answer from the code given below: Code:
Given below are two statements, one is labelled as Assertion (A) and other as Reason (R). Assertion (A): Various components of an ecosystem are not inter-dependent. Reason (A): Human activities have the impacts on the environment. Select the correct answer using the codes given below. Codes.
The entire sequence of communities that successively change in a given area are called as:
Generally, environment can be classified as following categories. Which among the following is not a part of such category?
Which one of the following is NOT a major cause of Wildlife Extinction?
With reference to Eutrophication, which of the following statement(s) is/are correct? 1. It decreases dissolved oxygen of water. 2. It is a phenomenon of nutrient enrichment of a water body. Select the correct answer from the codes given below: Codes:
The movement of nutrient elements through the various components of an ecosystem is called:
The concept of 'Ecological Transition' was first used by : Youtube - @UPSCneil
What is true about ecosystem?
The environment modified by human activities is called:
Which of the following statement is NOT true?
Which one of the following is the well known example of bio indicator of air pollution?
Given below are two statements, one is labeled as Assertion (A) and the other as Reason (R). Assertion (A): Maximum number of the species of butterflies is found in tropical countries. Reason (R): Butterflies can not tolerate low temperatures. Select the correct answer using the codes given below: Codes:
The amount of energy during transfer from one tropic level to another in an ecosystem
Which of the following is associated with biological nitrogen fixation?
Wildlife protection, biodiversity hotspots, national parks, sanctuaries, and conservation strategies.
Air, water, soil pollution, waste management, environmental impact assessment, and remediation.
Balancing development with environmental protection, green practices, and sustainability principles.
Government programs, environmental policies, conservation acts, and national initiatives.
International environmental agreements, COP meetings, protocols, and global cooperation.
Important environmental days, their themes, significance, and observances.
Renewable and non-renewable energy, solar, wind, nuclear power, and energy policy.
Recent environmental developments, reports, indices, and contemporary environmental issues.
Classification of Ecosystems Based on Water Flow: Lotic Ecosystems (Flowing Water): Rivers Lentic Ecosystems (Stagnant Water): Swamps, Ponds, Marshy area 2022
Year: UPPCS 2023Theme: BasicsThe limnetic zone is an open water area where sunlight penetrates, essential for phytoplankton. Other Aquatic Zones: Littoral Zone: Shallow waters near the shore; sunlight reaches the bottom, supporting diverse aquatic plants and animals. Profundal Zone: Deeper water below the limnetic zone; less light, supporting fewer photosynthetic organisms, more reliant on nutrients sinking from above. Benthic Zone: Bottom of the lake or pond, home to organisms that live in close association with or on the lake bed. 2022
Year: UPPCS 2022Theme: BasicsAn ecological niche includes a species' environmental tolerance, resource use, and functional role, with each species having a distinct niche reflecting its unique adaptations and interactions within the ecosystem. 2021
Year: UPPCS 2022Theme: BasicsEcosystem components are interdependent, ensuring stability, while human activities like pollution and habitat destruction disrupt this balance, affecting ecosystem sustainability. 2020
Year: UPPCS 2021Theme: BasicsA sere represents the progressive sequence of ecological communities, evolving from a pioneer stage to a climax community during ecological succession. The process continues until the ecosystem reaches a stable, balanced state, which is often resilient to change unless disturbed by external factors like human activities or natural disasters.
Year: UPPCS 2020Theme: BasicsPhysical Environment: Refers to the natural surroundings, including landforms, climate, water bodies, and atmosphere. Cultural Environment: Encompasses human-made surroundings and societal structures, such as traditions, customs, and heritage. Youtube - @UPSCneil Biological Environment: Includes all living organisms (plants, animals, and microorganisms) and their interactions with the surroundings.
Theme: Basics"To make fire in the forest" is not a major cause of wildlife extinction because forest fires, though harmful, are often part of natural cycles and can help regenerate ecosystems. While uncontrolled or human-induced fires can cause local harm, they are not typically a leading cause of large-scale wildlife extinction compared to habitat loss, illegal trade, or population pressure.
Theme: BasicsEutrophication involves nutrient enrichment (nitrogen, phosphorus) from runoff, leading to excessive algae growth. When algae decompose, oxygen consumption increases, resulting in reduced dissolved oxygen levels, which can cause hypoxic conditions and harm aquatic life.
Theme: BasicsThe bio-geo-chemical cycle refers to the movement of nutrient elements through the living (biotic) and non-living (abiotic) components of an ecosystem. These cycles include the carbon cycle, nitrogen cycle, water cycle, and others, each of which plays a crucial role in maintaining the balance and flow of essential nutrients in the environment.
Theme: BasicsBennett first used the concept of ‘Ecological Transition,’ which refers to changes in ecological conditions that lead to a shift in the distribution of species across an area. This concept is part of broader discussions on how environments and ecosystems evolve and respond to various factors, including human influence. Elton: Charles Elton was pivotal in developing the concept of food chains and ecological niches, not specifically ecological transitions. Ratzel: Friedrich Ratzel, a geographer, contributed to human geography and the notion of Lebensraum but was not the originator o
Theme: BasicsProducers outnumber primary consumers in most ecosystems, ensuring sufficient energy flow and resources to support higher trophic levels.
Year: UPPCS 2019Theme: Basics“Anthropogenic” means originating in human activity, highlighting how human interventions transform natural landscapes and ecosystems.
Theme: BasicsSpecies diversity generally decreases as one moves from the equator towards the poles. The equatorial regions, known for their warm climate and consistent sunlight, support a greater variety of species than the colder polar regions.
Theme: BasicsLichens absorb water and nutrients from the air, making them highly susceptible to airborne pollutants, which directly impact their growth and vitality.
Theme: BasicsButterflies generally struggle with low temperatures, which can impair their physiological functions and restrict their distribution to warmer climates. However, the reason butterflies are more numerous in tropical countries isn’t solely their inability to tolerate cold but also the richness of the environment which supports a diverse range of species.
Theme: BasicsThe energy transfer efficiency between trophic levels is generally around 10%, known as the 10% rule. This rule explains why higher trophic levels have less energy available and support fewer individuals compared to lower levels.
Theme: BasicsBlue-green algae, also known as cyanobacteria, are associated with biological nitrogen fixation. These organisms have specialized cells called heterocysts that provide an anaerobic environment necessary for the enzyme nitrogenase to function, facilitating the conversion of atmospheric nitrogen into ammonia, a form usable by Youtube - @UPSCneil plants. This process is crucial for enriching soil nitrogen content and supporting plant growth, especially in aquatic environments and rice paddies. SUSTAINABLE DEVELOPMENT 2023
Theme: BasicsThe definition of sustainable development used here originates from the Brundtland Report (officially titled “Our Common Future”), published in 1987 by the World Commission on Environment and Development (WCED).
Theme: Sustainable DevelopmentStatement 2: False. The Global Sustainable Development Report is produced every four years (quadrennial) to inform the High-Level Political Forum on Sustainable Development and not once every quarter. This report provides an in-depth review and analysis to support the discussions at the United Nations General Assembly and other high-level forums on sustainable development.
Theme: Sustainable DevelopmentRefer explanation of question 2 in this theme itself (sustainable development) Youtube - @UPSCneil 2019
Year: UPPCS 2020Theme: Sustainable DevelopmentSDG-6: Ensure availability and sustainable management of water and sanitation for all. SDG-7: Ensure access to affordable, reliable, sustainable, and modern energy for all. SDG-8: Promote sustained, inclusive and sustainable economic growth, full and productive employment and decent work for all. SDG-9: Build resilient infrastructure, promote inclusive and sustainable industrialization, and foster innovation.
Theme: Sustainable DevelopmentClub of Rome: In 1972, they published a report titled “The Limits to Growth,” which used computer models to project the consequences of unchecked economic and population growth with finite resource supplies. UNESCO: United Nations Educational, Scientific and Cultural Organization, primarily focused on promoting world peace and security through international cooperation in education, the sciences, and culture. Brundtland Commission: Officially known as the World Commission on Environment and Development, it is known for developing the concept of sustainable development Agenda 21
Theme: Sustainable DevelopmentXeri: Derived from the Greek word “xeros,” meaning dry. It is used to describe organisms or environments that are adapted to or characterized by dry, arid conditions. Arboreal: Pertaining to trees. Arboreal animals are those that live in trees and are adapted to climbing or moving among the branches. This term is used to describe organisms that spend a significant portion of their lives in trees. Fossorial: Relating to digging or burrowing. Fossorial animals are adapted for digging and often live underground, using their adaptations to create or navigate burrows.
Theme: ConservationIodine: Seaweeds are a significant source of iodine, an essential nutrient required for the production of thyroid hormones, which are critical for proper metabolism regulation in humans. Seaweeds, especially kelps and other brown algae, accumulate iodine from seawater, making them an important dietary source of this nutrient.
Theme: ConservationIn-situ Conservation: Refers to the conservation of species in their natural habitats. It is the most effective way of maintaining biological diversity and the evolutionary processes that go along with it. Examples include national parks, wildlife sanctuaries, and biosphere reserves. Ex-situ Conservation: Involves the conservation of species outside their natural habitats. This includes measures like botanical gardens, zoos, seed banks, and tissue culture. Ex-situ conservation is used primarily when in-situ conservation is not feasible or when species are extremely threatened in the
Theme: ConservationEucalyptus: Eucalyptus trees can be dangerous for the environment, particularly in areas where they are not native. These trees are known for their high water consumption, which can lead to decreased water availability for native plants and alteration of local water cycles. Additionally, eucalyptus trees produce chemicals that inhibit the growth of other plants around them (allelopathy), reducing biodiversity. Their highly flammable oils can also increase the risk and intensity of wildfires, posing further threats to ecosystems.
Year: UPPCS 2022Theme: ConservationThe Eco mark certification process evaluates products based on their ecological impact, including factors such as energy consumption, toxicity, and the ability to recycle or safely dispose of the product.
Theme: ConservationTropical Savanna Region: The tropical savanna region, also known as savanna or grassland, is famously known as the “Land of Big Game.” This region is characterized by its rolling grasslands, scattered trees, and diverse and abundant wildlife, including large mammals such as elephants, lions, and rhinoceroses. The savannas are most notably found in Africa, particularly in countries like Kenya, Tanzania, and South Africa, where wildlife safaris are a major attraction. POLLUTION 2023
Year: UPPCS 2019Theme: ConservationPesticide: Pesticides are typically not biodegradable and are considered persistent environmental pollutants. They can accumulate in the environment and in the tissues of organisms, leading to long-term ecological damage. Unlike natural waste products, many synthetic pesticides do not break down easily and can contaminate soil, water, and other natural resources. Youtube - @UPSCneil
Year: UPPCS 2023Theme: PollutionPollution assay in aquatic ecosystems: Biological Oxygen Demand (BOD) is a measure used to determine the amount of organic pollution in water. It refers to the amount of oxygen required by aerobic microorganisms to break down the organic materials present in a water sample at a certain temperature over a specific period of time. BOD is a critical indicator of the organic pollution level in water bodies, commonly used to assess the effectiveness of wastewater treatment and the impact of wastewater discharge on natural waters. 2022
Theme: PollutionOzone: Photochemical smog, often referred to as “summer smog,” is a type of air pollution that results from the interaction between sunlight and certain pollutants like volatile organic compounds (VOCs) and nitrogen oxides (NOx). Ozone is a primary component of photochemical smog. It is formed by the reaction of sunlight with these pollutants, particularly in urban areas with heavy traffic. Ozone at ground level, as part of smog, can be harmful to human health and the environment.
Year: UPPCS 2022Theme: PollutionNon-biodegradable pollutant: Dichloro-diphenyl-trichloroethane (DDT) is classified as a non-biodegradable pollutant. This means that it does not easily break down in the environment, leading to its accumulation in the soil and water bodies over time. DDT is known for its persistence and its ability to bioaccumulate in the food chain, leading to significant environmental and health impacts, including effects on wildlife and potential human health risks.
Theme: PollutionBangladesh: Bangladesh is notably affected by natural arsenic contamination in its groundwater. This issue is one of the largest environmental health disasters in terms of scale and severity. Millions of people in Bangladesh are exposed to drinking water with high levels of arsenic, which occurs naturally in high concentrations in the groundwater in many parts of the country.
Theme: PollutionNoble Gases: Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), Radon (Rn) Prominent Greenhouse Gases: Carbon dioxide (CO2), Methane (CH4), Nitrous oxide (N2O), Chlorofluorocarbons (CFCs), Water vapor (H2O)
Theme: PollutionWhisper: 30 dB; Normal conversation, Air Conditioner: 60 dB; Busy street traffic: 70-85 dB; Lawn mower, Vacuum cleaner: 85-90 dB; Concert, Sporting events: 95-110 dB; Motorcycles, Fireworks: 100-120 dB; Sirens: 110-129 dB; Rock concerts, Jackhammer: 110-120 dB 2021
Theme: PollutionThermal power plant: Fly ash pollution is predominantly caused by thermal power plants. Fly ash is a byproduct of burning pulverized coal in electric power generating plants. It consists of fine particles that rise with the flue gases. When coal is combusted, it generates ash, part of which becomes bottom ash collected at the furnace bottom, and the finer part, known as fly ash, is carried up into the exhaust stack.
Year: UPPCS 2021Theme: PollutionLichen: Lichens are well-known indicators of air pollution, particularly sulfur dioxide and other toxic compounds present in the atmosphere. Lichens are symbiotic organisms made up of fungi and algae (or cyanobacteria), which are sensitive to air quality changes. Their ability to absorb everything from the atmosphere due to their lack of roots makes them excellent bioindicators. When air pollution levels are high, lichen diversity and abundance typically decrease. 2020
Theme: PollutionNitrogen oxide: The term “nitrogen oxide” generally refers to several chemical compounds composed of nitrogen and oxygen, such as nitric oxide (NO) and nitrogen dioxide (NO2). These are not typically classified as naturally occurring greenhouse gases in the Earth’s atmosphere. They are primarily pollutants emitted from human activities like combustion processes (vehicles, power plants) and are major contributors to smog and acid rain.
Year: UPPCS 2020Theme: PollutionRise in Sea Level: Caused by the melting of ice and thermal expansion of seawater. Melting of Glaciers: Leads to reduced freshwater availability and contributes to sea- level rise. Spread of Diseases: Warmer temperatures enable the expansion of disease vectors like mosquitoes. Bleaching of Coral Reefs: Increased sea temperatures stress corals, causing bleaching and potential die-off. 2019
Theme: PollutionOxide of nitrogen and sulphur: Smog, particularly the type known as “industrial smog” or “gray smog,” is primarily caused by the atmospheric presence of oxides of nitrogen and sulfur. These compounds react with other elements in the atmosphere, often in the presence of particulate matter, under specific climatic conditions to form smog. This type of smog typically occurs in industrial areas and can be exacerbated by cold, damp weather. ENVIRONMENT SUMMITS AND OUTCOME 2023
Year: UPPCS 2019Theme: PollutionSustainable development: Agenda 21, adopted at the Earth Summit in Rio de Janeiro in 1992, is a comprehensive plan of action to be taken globally, nationally, and locally by organizations of the United Nations, governments, and major groups in every area in which humans impact the environment. Its primary focus is on sustainable development, encompassing social, economic, and environmental dimensions to achieve a balance among these factors for future generations. 2021
Year: UPPCS 2023Theme: Environment SummitsKyoto Protocol: The concept of ‘Carbon credit’ primarily originated from the Kyoto Protocol, which was adopted in December 1997 and came into force in February 2005. The protocol introduced mechanisms like the Clean Development Mechanism (CDM), Joint Implementation (JI), and Emissions Trading, which are all systems designed to help countries and corporations economically manage their carbon emissions. Carbon credits are part of these mechanisms, allowing entities to earn credits by reducing greenhouse gas emissions, which can then be traded to help meet international emissions reducti
Year: UPPCS 2021Theme: Environment SummitsKyoto Protocol is focused on reducing greenhouse gas emissions to mitigate climate change, not specifically on water conservation efforts. Cartagena Protocol — Biosafety: Correctly matched. It addresses the safe handling of genetically modified organisms. Stockholm Convention — Persistent Organic Pollutant: Correctly matched. It targets the reduction and elimination of persistent organic pollutants. Montreal Protocol — Ozone layer: Correctly matched. It aims to protect the ozone layer by phasing out substances that deplete it. NATIONAL CONSERVATION EFFORTS 2023
Year: UPPCS 2019Theme: Environment Summits1974: The Water (Prevention and Control of Pollution) Act was enacted in 1974 in India. This legislation was one of the first of its kind to explicitly focus on water pollution and aimed to prevent and control water pollution, as well as maintain or restore the wholesomeness of water. The act established the framework for regulating discharges of pollutants into waters to ensure water quality. 2022
Year: UPPCS 2023Theme: National Conservation Efforts1986: The Environment (Protection) Act was passed by the Government of India in 1986. This comprehensive legislation was enacted after the Bhopal Gas Tragedy and provides for the protection and improvement of the environment. It empowers the government to take all necessary measures to protect the environment and tackle various environmental challenges comprehensively. 2021
Year: UPPCS 2022Theme: National Conservation EffortsThe National Clean Air Programme (NCAP) was officially launched by the Government of India in January 2019. NCAP is a comprehensive plan to reduce air pollution levels across the country, with a target to achieve a 20-30% reduction in particulate matter concentrations by 2024, taking 2017 as the base year. The programme emphasizes city-specific air pollution reduction strategies, including measures to address vehicular emissions, industrial pollutants, and dust management.
Year: UPPCS 2020Theme: National Conservation EffortsWildlife Protection Act - Enacted in 1972, this act provides a legal framework for the protection of various species of plants and animals, sets up protected areas, and regulates hunting. Project Tiger - Launched in 1973, Project Tiger was initiated to protect tigers in India, which were at the time facing extinction, by establishing dedicated tiger reserves. Project Elephant - Initiated in 1992, this project aims to ensure the long-term survival of viable populations of elephants in their natural habitats by protecting them, their habitats, and migration corridors. Biological
Theme: National Conservation Efforts2 February is celebrated globally as World Wetlands Day. This date marks the anniversary of the signing of the Convention on Wetlands, also known as the Ramsar Convention, in Ramsar, Iran, on 2 February 1971. 2022
Year: UPPCS 2023Theme: Environment Related DaysApril 18: World Heritage Day May 22: International Day of Biodiversity July 29: International Tiger Day December 5: World Soil Day
Year: UPPCS 2022Theme: Environment Related DaysRenewable: Non-conventional energy sources are those energy sources that are renewable. This means they are derived from natural processes that are replenished at a faster rate than they are consumed. Examples include solar, wind, hydro (water), geothermal, and biomass energies. These sources are considered non-conventional mainly due to their sustainable nature and the technology used to harness them, which differs from traditional fossil fuel-based energy generation. Youtube - @UPSCneil 2022
Year: UPPCS 2023Theme: Energy SourcesNuclear energy is not an example of biomass energy. Biomass energy is derived from organic materials such as plant materials and animal waste, which are used to produce heat, electricity, or fuel. In contrast, nuclear energy is generated through nuclear fission processes using elements like uranium and thorium, which are not organic and do not originate from biological sources. 2021
Year: UPPCS 2022Theme: Energy SourcesPetroleum is a non-renewable energy source. It is formed from the decayed organic materials under high pressure and heat over millions of years, which means it cannot be replenished within a human lifespan or even many generations. Its extraction and consumption deplete existing reserves, leading to eventual scarcity. CURRENT AFFAIRS INSPIRED 2022
Year: UPPCS 2021Theme: Energy SourcesRachel Carson is the author of “Silent Spring,” published in 1962. This seminal work is often credited with launching the global environmental movement. In her book, Carson highlighted the adverse effects of pesticides on the environment, particularly on birds, and presented a compelling case against the indiscriminate use of synthetic chemical pesticides. 2019
Year: UPPCS 2020Theme: Current Affairs