Daily Static Quiz (Environment) Dec 20, 2025

Daily Static Quiz (Environment) Dec 20, 2025

Question 1

With reference to chemical processes occurring in water bodies, consider the following statements:

1. Biological Oxygen Demand (BOD) measures only the amount of organic matter that microorganisms can decompose under anaerobic conditions.

2. Chemical Oxygen Demand (COD) measures the amount of oxygen required to oxidize all oxidizable substances in water, both biodegradable and non-biodegradable.

3. A high BOD/COD ratio indicates that the pollutants in water are more readily biodegradable.

Which of the statements given above is/are correct?

(a) 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3

Question 2

Consider the following statements about kelp forests:

1. Kelp forests are found exclusively in tropical and subtropical waters with high temperatures.

2. Kelp can grow up to 60 centimeters (2 feet) in a single day under ideal conditions.

3. Kelp forests account for a significant portion of global primary productivity despite covering only a small fraction of Earth’s coastal areas.

4. Sea urchins play a role in ecosystem dynamics by controlling kelp growth, and their population explosions can lead to “urchin barrens.”

Which of the statements given above is/are correct?

(a) 1 and 2 only
(b) 2, 3 and 4 only
(c) 2 and 3 only
(d) 1 and 4 only

Question 3

The Global Mangrove Alliance was established to address which of the following environmental concerns?

1. Carbon sequestration in coastal ecosystems

2. Prevention of coastal erosion and storm surge protection

3. Reduction of microplastic accumulation in coastal waters

4. Restoration of biodiversity in tropical rainforests

Select the correct answer using the code given below:

(a) 1 and 2 only
(b) 1, 2 and 3 only
(c) 2, 3 and 4 only
(d) All of the above

Question 4

With reference to bioluminescence in marine organisms, consider the following:

1. Bioluminescence is produced when the enzyme luciferase catalyzes the oxidation of luciferin in the presence of oxygen.

2. Bioluminescence is primarily used by deep-sea organisms as a defense mechanism and for predator-prey interactions.

3. In the pelagic zones of the ocean, more than 75% of macro-planktonic organisms can emit light.

Which of the statements given above is/are correct?

(a) 1 only
(b) 1 and 2 only
(c) 2 and 3 only
(d) 1, 2 and 3

Question 5

Regarding India’s National Coal Gasification Mission, which of the following statements is/are correct?

1. The mission aims to achieve 100 million tonnes of coal gasification by 2030.

2. Underground Coal Gasification (UCG) pilot projects have been initiated in multiple coal-rich states.

3. Coal gasification is intended to replace coal burning entirely, eliminating all coal-based power generation.

4. The mission focuses on utilizing high-ash coal through gasification plants set up on BOO/BOM/LSTK basis.

Which of the above statements is/are correct?

(a) 1, 2 and 4 only
(b) 1 and 3 only
(c) 2 and 4 only
(d) All of the above

Question 6

The RoHS (Restriction of Hazardous Substances) Directive restricts the use of specific hazardous substances in electrical and electronic equipment. Which of the following substances fall under RoHS restrictions?

1. Polybrominated biphenyls (PBBs)

2. Lead and mercury compounds

3. Cadmium compounds

4. Certain phthalates and hexavalent chromium compounds

Select the correct answer:

(a) 1 and 2 only
(b) 1, 2 and 3 only
(c) 1, 2, 3 and 4
(d) 2 and 3 only

Question 7

With respect to radioactive effluents from nuclear power plants, consider the following statements:

1. Liquid radioactive effluents released from nuclear plants during normal operations are typically released at concentrations exceeding public dose limits set by regulatory agencies.

2. Noble gases such as xenon and krypton are among the primary contributors to atmospheric radioactive releases from nuclear plants.

3. Nuclear plants release more radioactive material during normal operations than coal-fired power plants.

Which of the statements given above is/are correct?

(a) 1 only
(b) 2 only
(c) 1 and 3 only
(d) 2 and 3

Question 8

With reference to methane hotspots and their detection, consider the following statements:

1. Methane hotspots are defined as concentrated areas of enhanced methane emissions that can be detected and monitored using satellite-based remote sensing technology.

2. Natural wetlands (such as the Sudd in South Sudan) are the largest persistent methane emission hotspots globally, surpassing anthropogenic sources.

3. The Methane Alert and Response System (MARS), powered by Copernicus Sentinel-5P satellite data, currently detects large methane plumes and hotspots in multiple sectors including fossil fuels, coal mining, waste, and agriculture.

4. Rice paddies account for approximately 10-12% of global methane emissions annually, primarily due to anaerobic decomposition facilitated by methanogenic archaea in continuously flooded conditions.

Which of the statements given above is/are correct?

(a) 1, 2 and 4 only
(b) 1, 3 and 4 only
(c) 1 and 4 only
(d) 2 and 3 only

Question 9

Consider the following statements about biomes and their characteristics:

1. Terrestrial biomes are primarily classified based on climate factors such as temperature, precipitation, and soil type.

2. Aquatic biomes are categorized into three main types based on salinity: freshwater (salinity less than 0.5 ppt), estuarine/brackish (salinity between 0.5 and 35 ppt), and marine (salinity greater than 35 ppt).

3. Boreal forests are characterized by permafrost and have higher biodiversity compared to tropical rainforests.

4. Biomes represent large geographical areas with distinct communities of organisms adapted to specific environmental conditions.

Which of the statements given above is/are correct?

(a) 1, 2 and 4 only
(b) 2, 3 and 4 only
(c) 1 and 3 only
(d) 1, 2, 3 and 4

Question 10

The Living Planet Index (LPI), which is used to track global biodiversity trends, is based on:

1. Population trends of vertebrate species across terrestrial, freshwater, and marine habitats.

2. Data from approximately 31,821 populations of over 5,230 vertebrate species.

3. Calculations using the geometric mean of relative abundance of populations.

4. Assessments conducted exclusively by governmental agencies without international collaboration.

Which of the statements given above is/are correct?

(a) 1, 2 and 3 only
(b) 2, 3 and 4 only
(c) 1 and 4 only
(d) 1 and 2 only

Answer Key and Explanations

Question 1: Answer – (b) 2 and 3 only

Explanation:

Statement 1 is INCORRECT. BOD measures the amount of oxygen required by microorganisms to decompose organic matter under aerobic conditions, not anaerobic. BOD is a standard indicator of water quality that reflects the degradation of organic pollutants by bacteria in the presence of dissolved oxygen.

Statement 2 is CORRECT. COD (Chemical Oxygen Demand) measures the total amount of oxygen needed to oxidize all oxidizable substances in water—both biodegradable organic compounds and non-biodegradable chemical substances. Unlike BOD, COD includes substances that microorganisms cannot decompose.

Statement 3 is CORRECT. A high BOD/COD ratio indicates that a substantial portion of the pollutants are biodegradable. Conversely, a low BOD/COD ratio suggests the presence of recalcitrant (non-biodegradable) compounds. This ratio is crucial for wastewater treatment decisions and environmental management.

Related Concept: UPSC frequently tests water quality parameters and the distinction between biodegradable and non-biodegradable pollutants. Understanding BOD/COD helps in assessing pollution severity and treatment feasibility.

Question 2: Answer – (b) 2, 3 and 4 only

Explanation:

Statement 1 is INCORRECT. Kelp forests thrive in cold, nutrient-rich waters, not tropical waters. They are found in temperate and polar coastal oceans. Kelp requires cool temperatures, attachment to the seafloor, and shallow water with adequate sunlight. They do not overlap with tropical ecosystems like coral reefs or mangrove forests.

Statement 2 is CORRECT. Kelp is a brown macroalga that can grow up to 60 centimeters (2 feet) per day under ideal physical conditions. Some kelp species can reach heights of 150 feet (45 meters), making them one of the fastest-growing organisms on Earth. The maximum growth rate is 60-61 centimeters per day.

Statement 3 is CORRECT. Although kelp forests and coral reefs combined cover only 0.1% of Earth’s total surface area, they account for approximately 0.9% of global primary productivity. This highlights their exceptional ecological importance despite their limited spatial extent.

Statement 4 is CORRECT. Sea urchins are primary herbivores in kelp forests. When sea urchin populations explode (often due to loss of predators or favorable conditions), they can overgraze kelp forests, preventing the growth of new kelp and creating “urchin barrens”—areas devoid of kelp and with reduced biodiversity. This is a classic example of trophic cascades in marine ecosystems.

Related Concept: Kelp forests represent one of Earth’s most productive ecosystems and are crucial for carbon sequestration. Recent declines due to climate change, warming waters, and invasive species are emerging environmental concerns tested in competitive exams.

Question 3: Answer – (b) 1, 2 and 3 only

Explanation:

Statement 1 is CORRECT. Mangroves are among the most carbon-rich ecosystems globally. The Global Mangrove Alliance was established with a primary focus on carbon sequestration and climate mitigation. Mangrove forests absorb 4-5 times more carbon emissions than tropical forests and store up to 15% of the world’s organic carbon in sediments. They are recognized as “blue carbon” ecosystems.

Statement 2 is CORRECT. Mangroves provide critical coastal protection by reducing the impact of storm surges, cyclones, and tsunamis. Their intricate root systems dissipate wave energy and prevent coastal erosion. This protective function has been demonstrated historically and is emphasized in international conservation initiatives.

Statement 3 is CORRECT. Research has revealed that mangroves act as a sink for microplastics. Their complex root structures trap and accumulate microplastics from the surrounding water, thereby reducing microplastic contamination in coastal and marine ecosystems. This environmental function was highlighted during recent World Environment Day discussions.

Statement 4 is INCORRECT. The Global Mangrove Alliance focuses specifically on coastal mangrove ecosystems, not tropical rainforests. While both are important for biodiversity and climate regulation, they are distinct ecosystems with different conservation strategies.

Related Concept: The Global Mangrove Alliance is a recent initiative mentioned in contemporary environmental discussions. Mangroves’ role in climate change mitigation, particularly through blue carbon sequestration, is an emerging topic in UPSC examinations.

Question 4: Answer – (d) 1, 2 and 3

Explanation:

Statement 1 is CORRECT. Bioluminescence is produced through a chemical reaction where the enzyme luciferase catalyzes the oxidation of the substrate luciferin in the presence of oxygen. This reaction releases energy in the form of visible light. The light produced is usually blue-green in color, which is the wavelength that transmits most efficiently through seawater.

Statement 2 is CORRECT. Bioluminescence serves multiple adaptive functions in deep-sea and marine organisms. These include: (1) predator defense—some organisms release a luminous cloud to confuse predators; (2) prey attraction—many deep-sea fishes use luminous lures to attract food; (3) species recognition and mating signals; and (4) visual communication in the darkness of the ocean depths where sunlight does not penetrate.

Statement 3 is CORRECT. A comprehensive study of deep-sea organisms shows that in pelagic (open ocean) ecosystems, more than 75% of macro-planktonic organisms are categorized as bioluminescent or likely bioluminescent. This demonstrates the prevalence and importance of bioluminescence in pelagic food webs, as opposed to benthic (seafloor) ecosystems where the percentage is lower.

Related Concept: Bioluminescence has emerged as an important ecological principle in recent environmental and marine biology discussions. It exemplifies adaptation to extreme environments and is relevant to understanding deep-ocean biodiversity and ecosystem functioning.

Question 5: Answer – (a) 1, 2 and 4 only

Explanation:

Statement 1 is CORRECT. The National Coal Gasification Mission, launched by India’s Ministry of Coal, explicitly aims to achieve 100 million tonnes (100 MT) of coal gasification capacity by 2030. This aligns with India’s energy security and climate change mitigation goals.

Statement 2 is CORRECT. India has initiated multiple coal gasification projects. Notably, Coal India Limited (CIL) and its subsidiaries have begun India’s first underground coal gasification (UCG) pilot project at the Kasta coal block in Jamtara, Jharkhand, positioning India at the forefront of this technology adoption.

Statement 3 is INCORRECT. Coal gasification is designed to complement, not replace, coal-based power generation. It is intended to provide alternative uses for coal (such as producing syngas for chemical synthesis, fertilizers, or fuel), thereby reducing dependence on coal combustion for electricity. Coal-based power generation will continue alongside gasification initiatives.

Statement 4 is CORRECT. Given India’s low availability of low-ash coal and the abundance of high-ash coal reserves, the National Coal Gasification Mission focuses on utilizing high-ash coal. Gasification plants are established on Build-Operate-Own (BOO), Build-Operate-Maintain (BOM), or Lump-Sum-Turnkey (LSTK) contract basis, with Coal India Limited responsible for coal mining and product marketing.

Related Concept: Coal gasification is part of India’s strategy to address climate change commitments while utilizing indigenous coal reserves. It falls under science and technology topics relevant to energy and environment in UPSC examinations.

Question 6: Answer – (c) 1, 2, 3 and 4

Explanation:

The RoHS (Restriction of Hazardous Substances) Directive is a European Union regulation restricting hazardous substances in electrical and electronic equipment. It currently restricts 10 substances:

Statement 1 is CORRECT: Polybrominated biphenyls (PBBs) are flame retardants restricted to a maximum of 1000 parts per million (ppm). Their use in electronics is prohibited due to their toxicity and persistence in the environment.

Statement 2 is CORRECT: Lead (Pb) and Mercury (Hg) are among the primary restricted substances in RoHS. Lead is present in solder, batteries, and certain components; mercury is found in switches and fluorescent displays. Both are highly toxic and persistent.

Statement 3 is CORRECT: Cadmium (Cd) is a toxic heavy metal restricted in RoHS because of its carcinogenic properties. It was historically used in certain electroplating processes and batteries.

Statement 4 is CORRECT: Hexavalent chromium (Cr6+) is a carcinogenic substance with a maximum allowed concentration of 1000 ppm. Certain phthalates (DEHP, BBP, DBP, and DIBP) are restricted plasticizers due to their reproductive and developmental toxicity.

Related Concept: RoHS compliance is increasingly relevant as India engages in electronics manufacturing and international trade. Understanding hazardous substance restrictions is important for environmental management and industrial policy.

Question 7: Answer – (b) 2 only

Explanation:

Statement 1 is INCORRECT. Radioactive effluents released from nuclear power plants during normal operations are carefully regulated and remain well within public dose limits set by regulatory bodies such as the U.S. Nuclear Regulatory Commission (NRC) and the Environmental Protection Agency (EPA). Plants follow the “As Low As Is Reasonably Achievable” (ALARA) principle to minimize releases.

Statement 2 is CORRECT. Noble gases such as xenon and krypton are among the primary contributors to atmospheric radioactive releases from nuclear plants. Xenon-133 (5.2-day half-life) is particularly common, and in some cases, krypton isotopes with shorter half-lives (krypton-87 with 76-minute half-life, krypton-88 with 2.8-hour half-life) are also released. These releases have been a focus of operational improvements over decades.

Statement 3 is INCORRECT. Coal-fired power plants actually release more radioactive material than nuclear plants during normal operations. Coal ash contains naturally occurring radioactive elements such as uranium, thorium, and their daughter nuclides. The radioactive content of coal fly ash can exceed that of nuclear plant effluents. This is a critical environmental fact that often surprises students.

Related Concept: Nuclear power plant effluents and their environmental impact represent a nuanced topic in environmental studies. Understanding both the actual risks and public perception is important for informed environmental policy discussions.

Question 8: Answer – (b) 1, 3 and 4 only

Explanation:

Statement 1 is CORRECT. Methane hotspots are defined as concentrated areas of enhanced methane emissions that can be detected and precisely monitored using satellite-based remote sensing technology. These point sources can be identified through imaging spectrometry and other advanced detection methods from space-based instruments like the Tropomi sensor on Copernicus Sentinel-5P, which provides daily global coverage with resolution of 7 km x 5.5 km. Hotspots are particularly significant because they represent localized, quantifiable emission sources that can be addressed through targeted mitigation efforts.

Statement 2 is INCORRECT. While natural wetlands (such as the Sudd in South Sudan with 4.5 million tonnes per year) are among the largest persistent methane emission hotspots, they do not surpass anthropogenic sources when considered globally. According to the Global Methane Assessment (GMA) conducted by UNEP and the Climate and Clean Air Coalition, anthropogenic methane accounts for 60% of total methane emissions, with the largest anthropogenic hotspot being oil and gas fields on the west coast of Turkmenistan (3.5 million tonnes per year). Additionally, rice paddies contribute 10-12% of global methane emissions from human activities.

Statement 3 is CORRECT. The Methane Alert and Response System (MARS), established by the United Nations Environment Programme (UNEP), uses Copernicus Sentinel-5P satellite data to detect large methane plumes and concentrated hotspots. As of 2025, MARS currently focuses on fossil fuels (oil and gas operations) with expansion to coal mining and waste sectors planned for 2025. MARS has sent over 3,500 alerts in 33 countries since its launch in 2022. It integrates data from multiple satellites to provide rapid, actionable, and transparent information for mitigation action.

Statement 4 is CORRECT. Rice paddies account for approximately 10-12% of global methane emissions annually. This is confirmed by the Intergovernmental Panel on Climate Change (IPCC) and multiple research studies. The high methane emissions from rice cultivation result from the anaerobic decomposition of organic matter in flooded soil conditions. Methanogenic archaea (microorganisms) utilize hydrogen and carbon dioxide in these oxygen-depleted environments to produce methane. Traditional continuous flooding practices maximize these anaerobic conditions. However, practices like alternate wetting and drying (AWD) can reduce methane emissions by 41.37% by introducing oxygen into the soil.

Related Concept: Methane hotspots and their detection through satellite monitoring have emerged as critical topics in contemporary environmental management and climate change mitigation strategies. The MARS system represents a significant development in global environmental governance and is directly relevant to India’s climate change commitments under the Global Methane Pledge and UNFCCC agreements.

Question 9: Answer – (a) 1, 2 and 4 only

Explanation:

Statement 1 is CORRECT. Terrestrial biomes are primarily classified based on abiotic factors, particularly:

• Climate: Temperature ranges and seasonal variations

• Precipitation: Annual rainfall and distribution patterns

• Soil type: Composition, nutrient content, and water retention capacity

These factors determine the type of vegetation and the animal communities adapted to each biome (e.g., deserts are characterized by low precipitation, tundras by extreme cold and permafrost, tropical rainforests by high temperature and rainfall).

Statement 2 is CORRECT. Aquatic biomes are classified based on salinity levels:

• Freshwater biomes: Salinity less than 0.5 parts per thousand (ppt) (rivers, lakes, ponds, streams)

• Estuarine/Brackish water: Salinity between 0.5 and 35 ppt – transitional zones between rivers and oceans

• Marine biomes: Salinity greater than 35 ppt (oceans, seas, coral reefs)

This classification reflects the physiological adaptations of organisms to different osmotic environments. Estuarine zones are further subdivided into oligohaline (0.5-5.0 ppt), mesohaline (5.0-18.0 ppt), and polyhaline (18.0-30.0 ppt) categories.

Statement 3 is INCORRECT. Boreal forests (taiga) have LOWER biodiversity compared to tropical rainforests. Boreal forests are characterized by:

• Low biodiversity with limited species

• Dominance of conifers and limited understory vegetation

• Short growing seasons and permafrost

In contrast, tropical rainforests are among the most biodiverse ecosystems on Earth, with thousands of plant and animal species per hectare. This is a fundamental ecological principle.

Statement 4 is CORRECT. A biome is defined as a large geographical area characterized by specific environmental conditions (temperature, precipitation, soil type) that support a distinct community of organisms (plants, animals, microorganisms) adapted through evolution to those particular conditions. Examples include deserts, grasslands, forests, and tundras.

Related Concept: Biome classification and characteristics are foundational concepts in ecology and have appeared in UPSC examinations, particularly in questions about ecosystem distribution, biodiversity hotspots, and environmental management.

Question 10: Answer – (a) 1, 2 and 3 only

Explanation:

Statement 1 is CORRECT. The Living Planet Index (LPI) is defined as an indicator of global biological diversity based on trends in vertebrate populations across all major habitat types:

• Terrestrial habitats: Mammals, birds, reptiles, amphibians

• Freshwater habitats: Freshwater fish, amphibians, and other vertebrates

• Marine habitats: Fish and marine mammals

The LPI thus provides a comprehensive picture of vertebrate population trends globally.

Statement 2 is CORRECT. As of 2022, the LPI is statistically constructed from peer-reviewed journal studies, online databases (e.g., GBIF – Global Biodiversity Information Facility), and government reports. The index encompasses data from approximately 31,821 populations of over 5,230 vertebrate species (including mammals, birds, reptiles, amphibians, and fish). This makes it one of the most comprehensive biodiversity assessment tools.

Statement 3 is CORRECT. The LPI calculations are based on the geometric mean of relative abundance of populations. This approach is mathematically chosen because:

• It provides a sensitive metric for detecting biodiversity change

• It serves as a “leading indicator” that can detect early signs of population decline

• It is statistically robust for comparing changes across disparate populations and species

The geometric mean gives equal weight to proportional changes in population sizes, making it suitable for comparing populations that vary widely in size.

Statement 4 is INCORRECT. The Living Planet Index is managed through international collaboration, not exclusively by governmental agencies. The Zoological Society of London (ZSL) manages the index in cooperation with the World Wide Fund for Nature (WWF). Additionally, data comes from scientists, research institutions, and conservation organizations worldwide. The LPI is also used by international organizations including the Convention on Biological Diversity (CBD) and is incorporated into the Kunming-Montreal Global Biodiversity Framework.

Related Concept: The Living Planet Index is an important international indicator of biodiversity status and has been adopted by multiple global biodiversity frameworks. It is increasingly relevant in discussions about climate change, conservation priorities, and sustainable development, making it a probable topic for UPSC examinations on global environmental initiatives and biodiversity assessment.

Daily Static Quiz