There were 15 Questions from Environment in 2024, of which

• 5 Questions were related to Climate Change
• 5 Questions were related to Environmental ecology
• 5 Questions were related to Bio-Diversity

The examiner covered areas such as the Basics of Climate Change, Global Climate Issues, Climate Change Initiatives, Alternate and Sustainable Fuels, the Basics of the Environmental ecology, the basics of biodiversity, Biodiversity in India, and Global Biodiversity and Environment Organisations.

The level of the questions was moderate.

Questions were aimed to test the basic and applied sections of  Environmental ecology,  Bio-Diversity.

Previous Year UPSC Environment Questions (PYQs) With Explanation 2024

1. One of the following regions has the world’s largest tropical peatland, which holds about three years worth of global carbon emissions from fossil fuels; and the possible destruction of which can exert detrimental effect on the global climate. Which one of the following denotes that region?

(a) Amazon Basin

(b) Congo Basin

(c) Kikori Basin

(d) Rio de la Plata Basin

1. Ans: b

Explanation: 

The Congo Basin is home to the world’s largest tropical peatlands, along with Brazil and Indonesia. The peat swamp forest of the Congo Basin stores around 29 billion tons of carbon – approximately equivalent to three years’ worth of global greenhouse gas emissions – while the Basin as a whole absorbs nearly 1.5 billion tons of carbon dioxide a year. The Basin stretches across six countries- Cameroon, Central African Republic, Democratic Republic of the Congo, Congo, Equatorial Guinea and Gabon. 

Hence, option b is correct. 

2. With reference to perfluoroalkyl and polyfluoroalkyl substances (PFAS) that are used in making many consumer products, consider the following statements:

1. PFAS are found to be widespread in drinking water, food and food packaging materials.

2. PFAS are not easily degraded in the environment.

3. Persistent exposure to PFAS, can lead to bioaccumulation in animal bodies.

Which of the statements given above are correct?

(a) 1 and 2 only

(b) 2 and 3 only·

(c) 1 and 3 only

(d) 1, 2 and 3

2. Ans: d

Explanation:

Perfluoroalkyl substances (PFASs) are substances commonly used in the production of various everyday objects, including among others kitchen dishes, cosmetics, or clothes. They penetrate to the environment and living organisms causing disturbances in the functioning of many internal organs and systems.

Per- and polyfluoroalkyl substances (PFAS) are a complex & ever-expanding group of manufactured chemicals widely used in everyday products. They are called ‘Forever Chemicals’ due to their non-degradability, long-term environmental persistence, and accumulation potential.

Hence, statement 2 is correct.

PFAS are used in many things we use daily and have extensive industrial and consumer applications, including non-stick cookware, food packaging, cleaning solutions, fire-fighting foam, stain/water resistant fabrics, and personal care items. 

PFAS compounds are considered ‘Contaminants of Emerging Concern’ as exposure to these has been associated with adverse human health issues such as reduced immune response, hormonal imbalances, low birth weight, etc., and even carcinogenic.

The presence of PFAS in drinking water due to the various environmental and health issues described above and in the environment is an urgent global public health issue that needs tremendous attention.

PFAS are used in the aerospace, automotive, construction, and electronics industries.  

Over time, PFAS may leak into the soil, water, and air.

Statement 1 is correct.

People are most likely exposed to these chemicals by consuming PFAS-contaminated water or food, using products made with PFAS, or breathing air containing PFAS. 

Multiple health effects associated with PFAS exposure have been identified and are supported by different scientific studies. Concerns about the public health impact of PFAS have arisen for the following reasons:

• Widespread occurrence: Studies find PFAS in the blood and urine of people, and scientists want to know if it causes health problems.
• Numerous exposures: PFAS are used in hundreds of products globally, with many opportunities for human exposure.
• Growing numbers: PFAS are a group of nearly 15,000 synthetic chemicals, according to a chemicals database (CompTox) maintained by the U.S. Environmental Protection Agency.
• Persistent: PFAS remain in the environment for an unknown amount of time.
• Bioaccumulation: People may encounter different PFAS chemicals in various ways. Over time, people may take in more of the chemicals than they excrete, a process that leads to bioaccumulation in bodies.

Statement 3 is correct.

3. Consider the following statements:

Statement-I: The Indian Flying Fox is placed under the “vermin” category in the Wild Life (Protection) Act, 1972.

Statement II: The Indian Flying Fox feeds on the blood of other animals.

Which one of the following is correct in respect of the above statements?

(a) Both Statement-I and Statement-II are correct and Statement-II explains Statement-I

(b) Both Statement-I and Statement-II are correct, but Statement-II does not explain Statement-I

(c) Statement-I is correct, but Statement-II is incorrect

(d) Statement-I is incorrect, but Statement-II is correct

3. Ans: c 

Explanation:

Vermin are wild animals or birds that destroy plants or food, or attack farm animals and birds

Wildlife Protection Act defines vermin –  “vermin” means any wild animal specified in Schedule V. 

SCHEDULE V of  Wild Life Protection Act consists of

 1. Common crow 

 2. Fruit bats 

 4. Mice 

 5. Rats 

Hence, statement 1 is correct.

The flying fox, also known as fruit bats or Pteropus gigante is listed as a ‘vermin’ in the Indian Wildlife (Protection) Act 1972, due to its destructive tendencies towards fruit farms.

The Indian flying fox is one of the largest species of bats in the world. Its wing length is 1.2-1.5m. It survives only on fruits.

Hence, statement 2 is incorrect.

4. The organisms “Cicada, Froghopper and Pond skater” are:

(a) Birds

(b) Fish

(c) Insects

(d) Reptiles

4. Ans: c

Explanation: 

Cicada, froghopper and pond skater all belong to the category of insects.

Hence, option c is correct. 

5. Consider the following statements:

Statement-I: Many chewing gums found in the market are considered a source of environmental pollution.

Statement-II: Many chewing gums contain plastic as gum base.

Which one of the following is correct in respect of the above statements?

(a) Both Statement-I and Statement-II are correct and Statement-II explains Statement-I

(b) Both Statement-I and Statement-II are correct, but Statement-II does not explain Statement-I

(c) Statement-I is correct, but Statement-II is incorrect

(d) Statement-I is incorrect, but Statement-II is correct

5. Ans: a

Explanation:

The earliest forms of gum were plant-based resins extracted from trees, most of the sticks we chew today are composed of synthetic petroleum derivatives – plastics. They include; butyl rubber, polythyene and polyvinyl acetate, which are also used in diesel, plastic bags and glue, respectively. These ingredients are often disguised under the name “gum base” on labels, and these plastics provide gum with chewiness.

Chewing gum contributes 100,000 tonnes of plastic pollution annually. An estimated 80-90% of chewing gum is not disposed of properly, making it the one of the most littered items on streets

Due to its plastic contents, chewing gum is non-biodegradable

Both statements  1 & 2 are correct, and statement 2  correctly explains statement 1.

6. Consider the following pairs:

How many of the pairs given above are correctly matched?

(a) Only one

(b) Only two

(c) All three

(d) None

6. Ans: d

Explanation:

Indris are the largest lemurs in the world. Like all lemurs, indris (Indri indri) are endemic to the island of Madagascar rainforests.

Elk, (Cervus elaphus canadensis), the largest and most advanced subspecies of red deer (Cervus elaphus), found in North America and in high mountains of Central Asia. It is a member of the deer family. 

Wild bonobos can only be found in forests south of the Congo River in the Democratic Republic of Congo (DRC). Bonobos and chimpanzees look very similar and both share 98.7% of their DNA with humans—making the two species our closest living relatives. Bonobos are usually a bit smaller, leaner, and darker than chimpanzees. 

None of the pairs are correctly matched, Hence, option d is correct. 

7. Consider the following statements:

1. Lions do not have a particular breeding season.

2. Unlike most other big cats, cheetahs do not roar.

3. Unlike male lions, male leopards do not proclaim their territory by scent marking.

Which of the statements given above are correct?

(a) 1 and 2 only

(b) 2 and 3 only

(c) 1 and 3 only

(d) 1, 2 and 3

7. Ans: a

Explanation:

There is no fixed breeding season, though the preponderance of mating appears to occur in winter. 

The Gir National Park spread across 1,412 sq km, was recently closed from June 16 to October 15  as part of lions mating season. 

Hence, statement 1 is correct.

Unlike other big cats, including lions, tigers, leopards, and jaguars, cheetahs don’t roar. They growl when there is danger, and usually only chirp, purr and meow.

Hence, statement 2 is correct.

Scent marking allows carnivores to communicate with each other by leaving their scent at prominent landmarks such as termite mounds and large trees in savannah ecosystems. These carnivores deposit their scent via scratching, rubbing, urinating, or defecating and often return to the same sites.

Such olfactory cues are used to mark territory, advertise dominance or reproductive status, and alert predators. 

Lions, Leopards and cheetahs will also ‘Sharpen their claws’ on the bark of a tree. Along with keeping their claws in good condition, there are glands in between their digits that leave their scent behind. The same glands deposit scent onto the ground and grass when the animal scratches their feet through the grass.

A male leopard locates and elicits response from a female in estrus, using scent marks and vocalisations.  

Hence, statement 3 is incorrect. 

8. Consider the following:

1. Battery storage

2. Biomass generators

3. Fuel cells

4. Rooftop solar photovoltaic units

How many of the above are considered “Distributed Energy Resources”?

(a) Only one

(b) Only two

(c) Only three

(d) All four

8. Ans: d

Explanation: 

Distributed energy resources are small, modular, energy generation and storage technologies that provide electric capacity or energy where you need it. 

DER systems can be made up of one or more primary technologies—such as internal combustion engines, combustion turbines, fuel cells, photovoltaics, wind turbines, and batteries 

DER technologies include wind turbines, photovoltaics (PV), fuel cells, microturbines, reciprocating engines, combustion turbines, cogeneration, and energy storage systems.

Examples of distributed energy resources that can be installed include:

• rooftop solar photovoltaic units
• wind generating units
• battery storage
• batteries in electric vehicles used to export power back to the grid
• combined heat and power units, or tri-generation units that also utilise waste heat to provide cooling
• biomass generators, which are fuelled with waste gas or industrial and agricultural by-products.
• open and closed cycle gas turbines
• reciprocating engines (diesel, oil)
• hydro and mini-hydro schemes
• fuel cells.

Hence, option d  is correct. `

9. Which one of the following shows a unique relationship with an insect that has coevolved with it and that is the only insect that can pollinate this tree?

(a) Fig

(b) Mahua

(c) Sandalwood

(d) Silk cotton

9. Ans: a

Explanation:

Figs have an obligate mutualism with tiny fig-pollinating wasps (family Agaonidae). Female wasps enter receptive syconia, where they pollinate female flowers. They also lay eggs in some flowers, where their larvae induce galls. Some weeks later, the wasp offspring emerge from their galls into the syconium, just as the male flowers have matured their pollen sacs. The new generation of female wasps leave the syconium through holes made by the males and carry pollen to receptive syconia elsewhere. This symbiosis is exploited by many species of fig-parasitic wasps. Most of them do not enter the syconium or contribute to pollination but use long ovipositors to inject eggs through the fig wall so that their larvae can feed on either fig flowers or other wasps.

Their interaction dominates the lives of both and, as each relies on the other for reproduction, 

 Figs are selected to raise some seeds (female function) and some wasps (male function as pollen vectors); however, wasps are selected to maximise their own offspring production, with no regard for seed production. This leads to the coevolution of various fig and wasp traits.

Hence, option a is correct. 

10. Which one of the following is the exhaust pipe emission from Fuel Cell Electric Vehicles, powered by hydrogen?

(a) Hydrogen peroxide

(b) Hydronium

(c) Oxygen

(d) Water vapour

10. Ans: d 

Explanation:

FUEL CELL ELECTRIC VEHICLE 

A fuel cell uses the chemical energy of hydrogen or other fuels to cleanly and efficiently produce electricity. If hydrogen is the fuel, the only products are electricity, water, and heat.

Fuel cell electric vehicles (FCEVs) powered by hydrogen are more efficient than conventional internal combustion engine vehicles. 

Hence, option d is correct.

11. Recently, the term “pumped-storage hydropower” is actually and appropriately discussed in the context of which one of the following? .

(a) Irrigation of terraced crop fields

(b) Lift irrigation of cereal crops

(c) Long-duration energy storage

(d) Rainwater harvesting system

11. Ans: c

Explanation:

PUMP STORAGE HYDROPOWER 

Pumped storage hydropower (PSH) is a type of hydroelectric energy storage. It is a configuration of two water reservoirs at different elevations that can generate power as water moves down from one to the other (discharge), passing through a turbine. 

Pumped storage hydropower plants store electricity by pumping water up from a lower reservoir to an upper reservoir and then releasing it through turbines when power is needed. They represent 30% of net hydropower additions through 2030 according to the IEA  forecast. 

The increasing need in many markets for system flexibility and storage to facilitate the integration of larger shares of variable renewables drives record growth of pumped storage projects between 2021 and 2030. 

Hence, option c is correct.

12. “Membrane Bioreactors” are often discussed in the context of:

(a) Assisted reproductive technologies

(b) Drug delivery nanotechnologies

(c) Vaccine production technologies

(d) Wastewater treatment technologies

12. Ans: d

Explanation:

Membrane Bioreactors (MBRs), have the advantage of combining a suspended growth biological reactor with solids removal via filtration. The membranes can be designed for and operated in small spaces and with high removal efficiency of contaminants such as nitrogen, phosphorus, bacteria, biochemical oxygen demand, and total suspended solids. 

The membrane filtration system in effect can replace the secondary clarifier and sand filters in a typical activated sludge treatment system. 

Membrane filtration allows a higher biomass concentration to be maintained, thereby allowing smaller bioreactors to be used. Membrane filtration involves the flow of water-containing pollutants across a membrane. Water permeates through the membrane into a separate channel for recovery. Because of the cross-flow movement of water and waste constituents, materials left behind do not accumulate at the membrane surface but are carried out of the system for later recovery or disposal. The water passing through the membrane is called the permeate, while the water with the more concentrated materials is called the concentrate or retentate.

A MEMBRANE BIOREACTOR (MBR)  process combines a microfiltration or ultrafiltration membrane unit with a suspended growth bioreactor and is now widely used in both municipal and industrial Wastewater Treatment Plants.

Hence, option d is correct.

 13. Consider the following materials:

1. Agricultural residues

2. Corn grain

3. Wastewater treatment sludge

4. Wood mill waste

Which of the above can be used as feedstock for producing Sustainable Aviation Fuel?

(a) 1 and 2 only

(b) 3 and 4 only

(c) 1, 2, 3 and 4

(d) 1, 3 and 4 only

13. Ans: c

Explanation:

Menu of Sustainable feedstock for producing Sustainable Aviation Fuel are:

1. Corn grain
2. Oil seeds
3. Algae
4. Other fats, oils, and greases
5. Agricultural residues
6. Forestry residues
7. Wood mill waste
8. Municipal solid waste streams
9. Wet wastes (manures, wastewater treatment sludge)
10. Dedicated energy crops.

Hence, option c is correct.

14. According to the Environmental Protection Agency (EPA), which one of the following is the largest source of sulphur dioxide emissions?

(a) Locomotives using fossil fuels

(b) Ships using fossil fuels

(c) Extraction of metals from ores

(d) Power plants using fossil fuels

14. Ans: d

Explanation:

According to EPA, the largest source of SO2 in the atmosphere is the burning of fossil fuels by power plants and other industrial facilities. Smaller sources of SO2 emissions include: industrial processes such as extracting metal from ore; natural sources such as volcanoes; and locomotives, ships and other vehicles and heavy equipment that burn fuel with a high sulfur content.    

Hence, option d is correct.

15. Consider the following statements:

Statement I: India does not import apples from the United States of America.

Statement II: In India, the law prohibits the import of Genetically Modified food without the approval of the competent authority.

Which one of the following is correct in respect of the above statements?

(a) Both Statement-I and Statement-II are correct and Statement-II explains Statement-I

(b) Both Statement-I and Statement-II are correct, but Statement-II does not explain Statement-I

(c) Statement-I is correct, but Statement-II is incorrect

(d) Statement-I is incorrect, but Statement-II is correct

15. Ans:  d

Explanation:

In June 2023  Indian Government removed an additional 20% duty was imposed on US apples in 2019. An additional 20% duty was imposed on US apples in 2019 in response to USA’s measure to increase tariffs on certain steel and aluminium products. There is no reduction on the Most Favoured Nation (MFN) duty on apples which is still applicable on all imported apples, including on the USA at 50%.

The market share of the US apples was taken by other countries due to the imposition of additional retaliatory duty on US apples. This is reflected as the import of apples from countries other than the US increased from US$ 160 million in FY 2018-19 to US$ 290 million in FY 2022-23. Turkey, Italy, Chile, Iran and New Zealand are other top exporters to India of apples which took the market share of the US. 

The import policy of Genetically Modified Food, Feed, Genetically Modified Organism (GMOs) and Living Modified Organisms (LMOs) has been notified by the Directorate General of Foreign Trade under General Notes regarding Import Policy in ITC (HS) 2012, Schedule-1 (Import Policy). As per the policy, import of GM food requires prior approval of the Genetic Engineering Approval Committee (GEAC) constituted by the Ministry of Environment Forest and Climate Change.

Further, the Customs Act, 1962 is the basic statute which governs /regulates entry/exit of different categories of goods into or outside the country. Various allied laws and regulations also apply. It is the responsibility of the Customs to ensure that all the imported/ exported goods fulfil the prescribed legal and procedural requirements laid down under the Customs act, 1962 and allied laws including payment of the duties leviable, if any.

Import of food products is regulated under the Food Safety and Standards Act (FSSAI), 2006. Indian Customs can clear food products including Genetically Modified(GM) food products only after necessary approval/No Objection Certificate(NOC) by FSSAI. FSSAI has informed that no genetically modified food has been cleared for import through the FSSAI locations.

Statement-I is incorrect, but Statement-II is correct.