There were 19 Questions from Environment in 2021, of which

• 8 Questions were related to Climate Change
• 8 Questions were related to  Environmental Ecology
• 3 Questions were related to Bio-Diversity

The examiner covered areas such as the Basics of Environmental Ecology, Basics of Climate Change and Climate  declaration, Basics of Biodiversity 

The level of the questions was moderate.

Questions were aimed  to test the basicunderstanding of the subject . 

Previous Year UPSC Environment Questions With Explanation 2021   

1. Consider the following statements: 

1. Right to the City is an agreed human right and the UN-Habitat monitors the commitments made by each country in this regard.

2. Right to the City’ gives every occupant of the city the right to reclaim public spaces and public participation in the city. 

3. ‘Right to the City’ means that the State cannot deny any public service or facility to the unauthorized colonies in the city. 

Which of the statements given above is/are correct?

(a) 1 only 

(b) 3 only

(c) 1 and 2 

(d) 2 and 3 

1. Ans: d

Explanation:

The right to the city is a new paradigm that provides an alternative framework to re- think cities and human settlements on the basis of the principles of social justice, equity, democracy and sustainability. 

It is the right of all inhabitants (present and future; permanent and temporary) to use, occupy, produce, govern and enjoy just, inclusive, safe and sustainable cities, villages and settlements defined as common goods. 

Right to the city is not an agreed human right.

Hence, statement 1 is incorrect.

It envisions the effective fulfillment of all internationally agreed Human Rights and Sustainable Development Goals, while dealing specifically with a dimension of urban problems that classic human rights’ standards do not tackle: namely, spatial exclusion, its causes and consequences. At the same time, it provides a territorial approach that can enhance policy pertinence and coherence. 

In this regard, it claims for (i) the social function of the city; (ii) quality public spaces; (iii) sustainable and inclusive rural-urban  linkages;  (iv) inclusive economies; (v)inclusive citizenship; (vi) enhanced political participation; (vii) non-discrimination; (viii) gender equality; and (ix) cultural diversity. 

Hence, statements 2 and 3 are correct.

2. Which one of the following is used in preparing a natural mosquito repellent?

(a) Congress grass

(b) Elephant grass

(c) Lemongrass

(d) Nut grass

2. Ans: c

Explanation:  

Natural barrier against mosquitoes:

• Lavender
• Marigold (or Calendula Officinalis)
• Lemongrass (Cymbopogon citratus)
• Aromatic herbs such as mint, basil, rosemary, savory, lemon balm
• Pelargonium and geranium
• as well as eucalyptus, catmint, petunia, nasturtium, etc.

About Lemongrass-

• Lemongrass commonly known as “East Indian Lemongrass” is a perennial and multicut aromatic grass. It is the source of Lemongrass oil, a good source of natural citral, which is used s a basic raw material for synthesis of a number of useful aromatic compounds and Vitamin- A. It is a main ingredient in soaps, deodorants and cosmetics. Its use as a bio-pesticide has not yet been fully tapped.
• Lemongrass oil is used in aromatherapy to reduce stress, anxiety and depression.
• Lemongrass leaves are the most commonly found plants in India. The lemongrass oil helps to get rid of mosquitoes. In addition to this, it is also used as cat, dog and even elephant repellant.
• It is widely distributed worldwide and most especially in tropical and subtropical countries. It flourishes in a wide variety of soils ranging from rich loams to poor laterite. The lemongrass cultivation has prevented soil erosion on hilly slopes.
• From being one of the largest importers of lemongrass till just a years back India became the largest exporter of it now.

Hence, option c is correct.

3. Consider the following kinds of organisms:

1. Copepods

2. Cyanobacteria

3. Diatoms

4. Foraminifera         

Which of the above are primary producers in the food chains of oceans?

a) 1 and 2

b) 2 and 3

c) 3 and 4

d) 1 and 4

3. Ans: b

Explanation:

The marine biome is the largest worldwide, covering three-quarters of the Earth’s surface. About 15% of all the species living on Earth, containing almost 300,000 species, are marine dwellers. The marine ecosystem consists of a series of interconnected producers and consumers.

Copepods

Copepods feed on microscopic algae and in turn serve as food for millions of other invertebrates and fish. The Copepoda are an incredibly numerous group of crustaceans. There are approximately 9000 species with an average size range of 0.5 to 15 mm. The largest copepods are parasitic ones that can reach as much as 25 cm in length.  

There are currently 10 groups of copepods. Most members of seven of those groups are parasites on other invertebrates or fish.

Cyanobacteria: Cyanobacteria are aquatic and photosynthetic, that is, they live in the water, and can manufacture their own food. Because they are bacteria, they are quite small and usually unicellular, though they often grow in colonies large enough to see. They have the distinction of being the oldest known fossils, more than 3.5 billion years old.

They are also important providers of nitrogen fertilizer in the cultivation of rice and beans.

The cyanobacteria have also been tremendously important in shaping the course of evolution and ecological change throughout earth’s history. The oxygen atmosphere that we depend on was generated by numerous cyanobacteria during the Archaean and Proterozoic Eras. Before that time, the atmosphere had a very different chemistry, unsuitable for life as we know it today.

The other great contribution of the cyanobacteria is the origin of plants. The chloroplast with which plants make food for themselves is actually a cyanobacterium living within the plant’s cells. Sometime in the late Proterozoic, or in the early Cambrian, cyanobacteria began to take up residence within certain eukaryote cells, making food for the eukaryote host in return for a home. This event is known as endosymbiosis, and is also the origin of the eukaryotic mitochondrion.

Because they are photosynthetic and aquatic, cyanobacteria are often called “blue-green algae”. This name is convenient for talking about organisms in the water that make their own food, but does not reflect any relationship between the cyanobacteria and other organisms called algae. Cyanobacteria are relatives of the bacteria, not eukaryotes, and it is only the chloroplast in eukaryotic algae to which the cyanobacteria are related.

Diatoms are abundant in both freshwater and marine ecosystems; it is estimated that 20% to 25% of all organic carbon fixation on the planet (transformation of carbon dioxide and water into sugars, using light energy) is carried out by diatoms. 

This is possible because they contain chlorophyll. Diatoms are thus a major food resource for marine and freshwater microorganisms and animal larvae, and are a major source of atmospheric oxygen.

Diatoms are a major component of plankton, free-floating microorganisms of marine or freshwater environments. Not all diatoms float freely though; many cling to surfaces such as aquatic plants, molluscs, crustaceans, and even turtles. Whales may carry dense growths of diatoms on their skin. Some may even be found in soils or on moist mosses.

Foraminifera

Foraminifera  are single-celled organisms (protists) with shells or tests (a technical term for internal shells). They are abundant as fossils for the last 540 million years. The shells are commonly divided into chambers that are added during growth. 

Depending on the species, the shell may be made of organic compounds, sand grains or other particles cemented together, or crystalline CaCO₃ (calcite or aragonite).

Fully grown individuals range in size from about 100 micrometers to almost 20 centimeters long. Some have a symbiotic relationship with algae, which they “farm” inside their shells. Other species eat foods ranging from dissolved organic molecules, bacteria, diatoms and other single-celled algae, to small animals such as copepods. They catch their food with a network of thin pseudopodia (called reticulopodia) that extend from one or more apertures in the shell. Benthic (bottom-dwelling) foraminifera also use their pseudopodia for locomotion.

Hence, option b is correct.

4. In nature, which of the following is/are most likely to be found surviving on a surface without soil?

1. Fern

2. Lichen

3. Moss

4. Mushroom

Select the correct answer using the code given below.

(a) 1 and 4 Only

(b) 2 Only

(c) 2 and 3

(d) 1, 3 and 4

4. Ans: c

Explanation:

Algae, lichens, liverworts, and moss are often in nature found growing in damp or shady places in the garden on plants, soil and hard surfaces, they even can grow without soil. 

Lichens: 

Lichens are a complex life form that is a symbiotic partnership of two separate organisms, a fungus and an alga. The dominant partner is the fungus, which gives the lichen the majority of its characteristics, from its thallus shape to its fruiting bodies. The alga can be either a green alga or a blue-green alga, otherwise known as cyanobacteria. Many lichens will have both types of algae. 

What are fungi?

• Fungi are a diverse group of organisms that are in their own kingdom (Fungi), separate from plants. Fungi do not contain chlorophyll or any other means of producing their own food so they rely on other organisms for nutrition. Fungi are widely known for their role in the decomposition of organic matter. They are also necessary for the survival of the ecosystem around them, such as partnering with plants and trees for nutrients and survival.

What are algae?

• Algae are in another kingdom (Protista) separate from plants and fungi. There are several types of algae: green, brown, red, gold. They can survive in salt water and in freshwater on their own, and in any environment when part of a lichen relationship.
• Although cyanobacteria are called blue-green algae, they are actually bacteria, and are part of the bacteria kingdom, Monera. The “blue” in the common name refers to the fact that they need to live in water, and “green algae” refers to their photosynthetic abilities, like green algae.

Lichens, do not have any roots, stems or leaves and their chloroplasts are contained only in the algae on the top surface of the lichen.

Important function of lichens is that they provide a mode of survival in harsh environments, 

lichens directly benefit humans is through their ability to absorb everything in their atmosphere, especially pollutants. Lichens can provide us with valuable information about the environment around us. Any heavy metals or carbon or sulfur or other pollutants in the atmosphere are absorbed into the lichen thallus.

Lichens can be seen hanging off of trees or clinging to rocks. 

Mosses:   

• Mosses are very primitive, the ancestors of the trees, they have plant-like structures that look like and function like leaves, stems and roots. They have chloroplasts throughout their entire bodies and can photosynthesize from all sides of their structures.
• Mosses along with lichens are the first organisms to colonise rocks and hence, are of great ecological importance. They decompose rocks making the substrate suitable for the growth of higher plants

Ferns

• Ferns are plants that do not have flowers. Ferns generally reproduce by producing spores. Similar to flowering plants, ferns have roots, stems and leaves. 
• However, unlike flowering plants, ferns do not have flowers or seeds; instead, they usually reproduce sexually by tiny spores or sometimes can reproduce vegetatively
• The ferns are an ancient lineage of plants, dating back to at least the Devonian. They include three living groups — Marattiales, Ophioglossales, and leptosporangiate ferns — as well as a couple of extinct groups.  
• Ferns are plants that do not have flowers. Ferns generally reproduce by producing spores. Similar to flowering plants, ferns have roots, stems and leaves. However, unlike flowering plants, ferns do not have flowers or seeds; instead, they usually reproduce sexually by tiny spores or sometimes can reproduce vegetatively.

Mushrooms

• Mushrooms are the reproductive structures (fruiting bodies) of organisms that otherwise live as microscopic threads of cells in various substrates such as soil, wood, or living tissues of associated plants.  
• The threadlike cells (hyphae) in mass are referred to as the mycelium. Fruiting bodies are produced from the mycelium to carry out sexual reproduction-the formation and release of spores.
• Spores allow fungi to disperse and survive until conditions are right for germination and establishing a new colony. 
• Fungi generally are classified as pathogens, saprobes, and mutualists .
• Pathogens attack and often kill living tissues and may kill the host organism .
• A true saprobe lives only on dead organic matter such as heartwood of standing trees, woody debris, or fallen leaves .
• saprobes decompose the organic layers of the forest floor: stems, branches, and leaves. 
• The genera Aleuria, Clitocybe, Collybia, Marasmius, Morchella, Mycena, Naemataloma, Phoiiota, and Scutellinia represent some of the variety of saprobes
• Fungi interact with many soil organisms, including bacteria, other fungi, nematodes, microarthropods, and insects. They serve as prey to and predators of organisms in these group.
•  A large portion of the total forest ecosystem biomass resides in the living fungi, which rapidly die and recycle their nutrients to the soil. This great fungal component not only recycles nutrients but also captures significant amounts of forest nutrients, which reduces leaching loss from the system. 
• Mutuatlism 
• Third major group of fungi, the mutuatists, live in intimate association with plants and interact in various ways that, in this instance, benefit both partners, hence, mutuatistic symbiosis. Among fungi, the predominant mutualistic symbiosis in forests takes place with plant roots producing structures called mycorrhizae. 
• Mycorrhiza literally translates as “fungus-root” 
• The mycorrhizal fungus basically serves as an extension of the plant root system, exploring soil far beyond the reach of the roots and transporting water and nutrients to the roots. The uptake of phosphorus and nitrogen are especially critical functions of mycorrhizal fungi, which can release bound forms of these nutrients otherwise unavailable to the roots. In return, the plant is the primary energy source for the fungus, providing simple sugars and vitamins produced in photosynthesis and transported to the roots and then the fungus.
• Mycorrhizal fungi are less capable of decomposing complex carbon molecules from organic debris than are saprobes. This dependency of fungi on their hosts for growth and survival is critical to mushroom production by mycorrhizal fungi.

Hence, option c is correct.

5. Consider the following statements:

Statement 1: The United Nations Capital Development Fund (UNCDF) and the Arbor Day Foundation have recently recognized Hyderabad as 2020 Tree City of the World.

Statement 2: Hyderabad was selected for the recognition for a year following its commitment to grow and maintain the urban forests.

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

a) Both Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation of Statement 1

b) Both Statement 1 and Statement 2 are correct and Statement 2 is not the correct explanation of Statement 1

c) Statement 1 is correct but Statement 2 is not correct

d) Statement 1 is not correct but Statement 2 is correct

5. Ans: d

Explanation:

The Tree Cities of the World programme is an international effort to recognise cities and towns committed to ensuring that their urban forests and trees are properly maintained, sustainably managed, and duly celebrated. 

The Food and Agriculture Organization of the United Nations and the Arbor Day Foundation have developed this programme to celebrate greener cities and towns worldwide.

Hyderabad has become the only city in India to be recognised as a ‘Tree City of the World’ by the Arbor Day Foundation and the Food and Agriculture Organization (FAO) of the United Nations not the United Nations Capital Development Fund (UNCDF).

Hence, statement 1 is incorrect & statement 2 is correct.

6. ‘R2 Code of Practices’ constitutes a tool available for promoting the adoption of

(a) environmentally responsible practices in electronics recycling industry

(b) ecological management of ‘wetlands of International Importance’ under the Ramsar Convention

(c) sustainable practices in the cultivation of agricultural crops in degraded lands

(d) ‘Environmental Impact Assessment’ in the exploitation of natural resources

6. Ans: a

Explanation: 

“Responsible Recycling practices for Use in Accredited Certifications Programs” (R2) Practices: To Recognize the need for comprehensive best-practices to address the operational and environmental challenges in electronics recycling and repair, 

In 2008, the R2 Practices were released and repair and recycling facilities began to get certified.

The original R2 Practices went through its first major revision in 2013 and released a second upgrade, R2v3, in 2020.

Sustainable Electronics Recycling International (SERI) was established as a non-profit organization in 2014 to succeed R2 Solutions with a mission that extends beyond the R2 Standard.

Hence, option a is correct.

7. Why is there a concern about copper smelting plants?

1. They may release lethal quantities of carbon monoxide into environment.

2. The copper slag can cause the leaching of some heavy metals into environment.

3. They may release sulphur dioxide as a pollutant.

Select the correct answer using the codes given below.

(a) 1 and 2 Only

(b) 2 and 3 Only

(c) 1 and 3 Only

(d) 1, 2 and 3

7. Ans: b

Explanation:

Copper Smelting:

During the extraction of the copper from the cuprous oxide, it can be easily reduced from the oxides of copper ore to directly metal by heating with coke. The reducing agent in this process could be carbon, carbon monoxide and carbon dioxide as well. Therefore, the carbon monoxide produced by heating copper ore with oxygen again as a reducing agent. Hence the CO2 and CO emission from copper industries are bare minimum when compared  to other metal production as per MoEF document on greenhouse gas emission inventory. 

Hence, statement 1 is incorrect.

Copper smelting causes air, water and land pollution. The process releases sulphur dioxide gas, a known pollutant that causes respiratory ailments. 

The smelting process also releases radon, iron, manganese, lead, arsenic, nitrates and fluorides, which reach the water sources and the soil through the industrial slag.

Hence, statements 2 and 3 are correct.

8. With reference to furnace oil, consider the following statements:

1. It is a product of oil refineries.

2. Some industries use it to generate power.

3. Its use causes sulphur emissions into the Environment.

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

8. Ans: d

Explanation:

Furnace oil is also called fuel oil, heavy oil (because it is heavier than petrol or naptha), marine fuel, bunker oil, or gas oil. The furnace fuel primarily consists of residues from crude oil distillation. Furnace oil is obtained from the flammable liquids acquired from crude oil and is also named kerosene.

Furnace Oil is one of the cheapest fuels available for industrial use. It is a by-product of petroleum refineries. While processing the Crude Oil, FO ( Furnace Oil ) is one of the products along with other petroleum fuels like High Speed Diesel, Petrol etc.

Hence, statement 1 is correct.

Uses of Furnace Oil are :

• As fuel for Power Generation in DG Sets
• As fuel for Boilers/ Furnaces/ Air preheater/ Any other Heaters
• Fuel for Bunkering
• Fuel/ Feedstock in Fertilizer Plants

Hence, statement 2 is correct.

Burning of Furnace oil produces sulphur dioxide (SO2), methane, carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions.

Hence, statement 3 is correct.

9. What is blue carbon?

a) Carbon captured by oceans and coastal ecosystems

b) Carbon sequestered in forest biomass and agricultural soils

c) Carbon contained in petroleum and natural gas.

d) Carbon present in atmosphere

9. Ans: a

Explanation: 

Blue carbon is the carbon stored in coastal and marine ecosystems. Coastal ecosystems including mangroves, tidal marshes and seagrass meadows sequester and store more carbon per unit area than terrestrial forests and are now being recognised for their role in mitigating climate change. 

Hence, option a is correct.

10. Consider the following animals:

1. Hedgehog

2. Marmot

3. Pangolin

To reduce the chance of being captured by predators, which of the above organisms rolls up/roll up and protects/ protect its/their vulnerable parts?

(a) 1 and 2

(b) 2 only

(c) 3 only

(d)1 and 3

10. Ans: d

Explanation:

Reason for rolling up by organisms:

• For some animals, the first and only way to defend themselves is to hide. Rolling into a ball-like shape presents the harder and sometimes more dangerous part of their body to their predator to protect their vulnerable part.
• Hedgehogs while coming back down on surfaces curl inward and drop down, the fall is cushioned by their exterior.
• Certain animals are unable to migrate as the season change. This puts them at risk of harsh elements during the colder and drier months. To preserve themselves, they curl into a ball shape to wait the weather out.

The armadillo, pangolin, hedgehog, chiton,  Armadillo Girdled Lizard, Golden Wheel Spider, and Isopods are common animals that roll into a ball. However, that list extends longer to include some unlikely creatures like spiders and aquatic animals.

Hedgehogs

• In hedgehog, the ear pinna is large, zygomatic arc is present and robust, occiput is flat or concave. The bullae are incomplete, tympanic bones form an annulus, the first and second molars are quadrate and low cusped. The testes are ventral but non-scrotal. The dorsum of the hedgehog is covered with stout spines, the venture is furred, and the tail is very reduced. 
• Indian long-eared hedgehog is an endemic species in the region distributed in the arid zones of northwest India (east to Agra, north to Jammu, south as far as Pune) and Pakistan (west to Indus).
• Indian Hedgehog and Madras Hedgehog are species endemic to South Asian and distributed in the arid zone of Pakistan and northwest India from the Indus river to the east in Agra, and south to Kathiwar peninsula and even recorded from the south Indian states of Tamil Nadu and Kerala.

Marmots

• Marmots  are relatively large ground squirrels.Two species of marmots (comprising 15 species worldwide) occur in South Asia, in the alpine and cold desert regions of higher Himalaya and Trans-Himalaya in India, Nepal and Pakistan. 
• They are burrowing squirrels that live in holes in the ground. They are stout with a squat build, a short to moderate-sized bushy tail, and small ears. Unlike of the solitary territorial tree squirrels, they live in large colonies and are social animals. They live in burrows that have several entrances, excavated in well drained soil. 
• They  have a long hibernation period, sleeping upto nine months in a year, though may emerge briefly during spells of mild weather. They typically emerge in spring.
• Their food includes roots, leaves, grasses, herbs, forbs and sedges. Their anti-predatory behavious is well-documented, they utter a whistling scream to warn other individuals of the colony, and run into their shelter.

Pangolins

• The pangolins are scaly anteaters survive as a single family and are distributed in the Old World Tropic.
• Pangolins aree myrmecophagus, specialised for feeding on ants and termites. The long claws and powerful limb muscles allow them to dig into termite mounds and also to construct burrows. The teeth are absent and tongue is extremely long .
• When attacked pangolins roll into a ball and make their scales erect. Yet another method of defence employed is the erection of well-directed jets of an ill-smelling liquid from the naal region.
• Most species are terrestrial and nocturnal, while retaining the ability to climb trees. It may use tree cavities as well as burrows to nest. Normally quadrupedal, pangolins when running assume a bipedal gait with the tail acting as a counterbalance. 
• They are considered as habitat engineers as they dig soil to live and feed helping soil aeration and mineral fixation. The abandoned burrows act as shelter for many fossorial animals. 

Hence, option d is correct.

11. With reference to the ‘New York Declaration on Forests’. Which of the following statements are correct?

1. It was first endorsed at the United Nations Climate Summit in 2014.

2. It endorses a global timeline to end the loss of forests.

3. It is a legally binding international declaration.

4. It is endorsed by governments, big companies, and indigenous communities.

5. India was one of the signatories at its inception.

Select the Correct answer using the code given below.

(a) 1, 2 and 4

(b) 1, 3 and 5

(c) 3 and 4

(d) 2 and 5

11. Ans: a

Explanation:

The New York Declaration on Forests (NYDF) is a political declaration calling for global action to protect and restore forests. NYDF was first endorsed at the United Nations Climate Summit in September 2014. 

Hence, statement 1 is correct.

New York Declaration on Forests (NYDF) emphasises on ten goals which includ include halting natural forest loss by 2030, restoring 350 million hectares of degraded landscapes and forestlands, improving governance, increasing forest finance, and reducing emissions from deforestation and forest degradation as part of a post-2020 global climate agreement.

Hence, statement 2 is correct.

The New York Declaration on Forests (NYDF) is a voluntary and non-binding international declaration to take action to halt global deforestation.  

Hence, statement 3 is incorrect.

It has presently over 200 endorsers – including national governments, subnational governments, companies, indigenous groups, financial institutions and NGOs. These endorsers have committed to doing their part to achieve the NYDF goals and follow its accompanying action agenda. 

Hence, statement 4 is correct.

Presently, India has not signed the New York Declaration on Forests (NYDF).

Hence, statement 5 is incorrect.

12. Magnetite particles, suspected to cause neurodegenerative problems, are generated as environmental pollutants from which of the following?

1. Brakes of motor vehicles

2. Engines of motor vehicles

3. Microwave stoves within homes

4. Power plants

5. Telephone lines

Select the correct answer using the code given below

(a) 1, 2, 3 and 5 Only

(b) 1, 2 and 4 Only

(c) 3, 4 and 5 Only

(d) 1, 2, 3, 4 and 5

12. Ans: b

Explanation: 

Magnetite Particles:

• Magnetite are the biologically and anthropologically  formed nanoparticles of the strongly magnetic mineral.
• These particles can also originate from different sources, including fossil fuel combustion in motor vehicle emissions, lubricating oil, vehicle brake abrasion, abrasion and corrosion of vehicle engines, coal burning, and waste burning, iron impurities in burning fuel—especially diesel—and indoor sources such as printer toners, and leaky stoves.
• The use of coal for industrial applications such as coking in the production of steel and in power plants is indicated to be a major source of spherical magnetic combustion-associated magnetite fine particles and nanoparticle environmental pollution.
• These particles were first detected in the human brain over 20 years ago. Given their toxicity, abundance in roadside air, and nanoscale dimensions, traffic-derived magnetite pollution nanoparticles may constitute a chronic and pernicious neurotoxicant.
• As many of the airborne magnetite pollution particles are <200 nm in diameter, they can enter the brain directly through the olfactory nerve and by crossing the damaged olfactory unit. Magnetite can have potentially large impacts on the brain due to its unique combination of redox activity, surface charge, and strongly magnetic behavior. Therefore magnetite particles have been seen as contaminants in the environment.

Hence , option b is correct.

13. Which one of the following is a filter feeder?

a) Catfish

b) Octopus

c) Oyster

d) Pelican

13. Ans: c

Explanation:

Filter feeders:

• Filter feeders are aquatic animals that obtain food by straining particles and small organisms out of water. They do this by moving through the water or taking advantage of water moving by them. Filter feeders typically pass water over a specialized filtering structure. 
• They use various filamentous structures to capture food particles from the water, such as bristles, cilia, or tentacles, by creating feeding currents or acting as sieves to intercept particles from suspension passing through.
• Oysters are filter feeders, belong to mollusks that remove plankton, bacteria and toxins from the water and even increase ecosystem health.
• They can remove excess nitrogen and nitrates from water and incorporate it into their shells and tissue. 
• Near oyster reefs, the water is often clearer.
• Some other filter feeders in nature include mussels, clams, krills, baleen whales, mollusks, sponges, flamingos, a few species of ducks and geese, manta rays, whale sharks (the largest fish in the world) and basking sharks.

Hence, option c is correct.

14. In the case of which one of the following biogeochemical cycles, the weathering of rocks is the main source of release of nutrients to enter the cycle?

(a) carbon cycle

(b) Nitrogen cycle

(c) Phosphorus Cycle

(d) Sulphur Cycle

14. Ans: c

Explanation:

Phosphorus is a major constituent of biological membranes, nucleic acids and cellular energy transfer systems. Many animals also need large quantities of this element to make shells, bones and teeth. P is the eleventh most abundant element in the Earth’s crust.

The Phosphorus Cycle 

• It is the biogeochemical cycle that describes the transformation and translocation of phosphorus in soil, water, and living and dead organic material. 
• Phosphorus additions to soil occur due to additions of inorganic and organic (manure) fertilizer and the degradation and decomposition of organic (plant and animal) material. 
• The natural reservoir of phosphorus lies in the rocks, fossils, etc. which contains phosphorus in the form of phosphates. which is excavated by man for using it as Fertiliser.
• Export of P from soil occurs mainly through plant uptake. When rocks are weathered, minute amounts of these phosphates dissolve in soil solution and are absorbed by the roots of the plants. Herbivores and other animals obtain this element from plants. 
• Phosphorus may also be exported from soil via surface runoff and erosion or subsurface loss through leaching. A good proportion of phosphates moving with surface run-off reaches the oceans and are lost into the dep sediments. 
• Sea birds also play an important role in phosphorus cycling. They eat sea fishes which phosphorus rich and the droppings or excreta of the birds return the phosphorus on land. The Guano deposits on the coast of Peru are very rich sources of phosphorus.
• The waste products and the dead organisms are decomposed by phosphate-solubilising bacteria releasing phosphorus back into the soil.
• Unlike carbon cycle, there is no respiratory release of phosphorus into atmosphere.

In the Sulphur cycle, the ocean represents a major reservoir of sulfur on Earth, with large quantities in the form of dissolved sulfate and sedimentary minerals (e.g., gypsum and pyrite).

Hence, option c is correct.

15. Which of the following are detritivores?

1. Earthworms

2. Jellyfish

3. Millipedes

4. Seahorses

5. Woodlice

Select the correct answer using the code given below.

(a)1, 2 and 4 Only

(b) 2, 3, 4 and 5 Only

(c) 1, 3 and 5 Only

(d) 1, 2, 3, 4 and 5

15. Ans: c

Explanation: 

Two groups of organisms responsible for the decomposition of dead organic matter (detritus): bacteria and fungi are called decomposers, while animals that consume dead matter are known as detrivores.

Detritivores play a crucial role in the biogeochemical processes of soil and nutrient cycling through their consumptive and burrowing activities. In a food web nutrients are recycled in the end by decomposers. Decomposers work at every level, setting free nutrients that form an essential part of the total food web. 

Detritivores 

• A detritivore is a heterotrophic organism, which obtains its nutrition by feeding on or consuming detritus (plus any associated bacteria and fungi). Detritus is the organic matter made up of dead plant and animal material. 
• Detritivores may also obtain nutrition by coprophagy, which is a feeding strategy involving the consumption of feces.
• Detritivores are often invertebrate insects such as mites, beetles, butterflies and flies; mollusks such as slugs and snails; or soil-dwelling earthworms, millipedes and woodlice.
• Examples of detritivores in marine environments are crustaceans such as crabs and lobsters, echinoderms such as sea stars or sea cucumbers. 
• Many of these marine detritivores occupy a similar niche to terrestrial soil-dwellers, living on or within the seabed known as the benthos. These organisms are often called “bottom-feeders”. 

Millipedes are arthropods and, unlike insects, do not have three clearly defined body sections, each with a pair of legs. Millipedes are worm-like animals with numerous body segments and legs, feed on decaying plant matter and are found in moist environments, as they cannot survive long in dry conditions. 

Earthworms are important organisms in soil communities and are known for sustaining the life of the soil. They are used as a model organism in environmental risk assessment of chemicals and soil toxicology. Soil provides physical and nutritive support to the agriculture system by regulating biogeochemical cycles, nutrient cycle, waste degradation, organic matter degradation etc. 

Woodlice (also called sow bugs, pill bugs and slaters) are terrestrial isopods (class of Crustacea) which have invaded terrestrial habitats from aquatic environments. Most species can still tolerate submersion in water saturated with O2. They can remove heavy metals such as cadmium, arsenic and lead by ionising it, so preventing metal ions leaching in to groundwater.

 Their diet consists mostly of decaying organic materials such as leaf litter, decayed wood, fungi, and bacterial mats. 

Hence, option c is correct.

16. The ‘Common Carbon Metric’, supported by UNEP, has been developed for

(a) assessing the carbon footprint of building operations around the world

(b) enabling commercial farming entities around the world to enter carbon emission trading

(c) enabling governments to assess the overall carbon footprint caused by their countries

(d) assessing the overall carbon foot-print caused by the use of fossil fuels by the world in a unit time

16. Ans: a

Explanation:

The Common Carbon Metric is the calculation used to define measurement, reporting, and verification for GHG emissions associated with the operation of buildings types of particular climate regions. 

This sector represents 40% of the world’s energy consumption and related 1/3rd of global greenhouse gas (GHG) emissions.

The CCM is developed by the United Nations Environment Program’s Sustainable Buildings & Climate Initiative (UNEP-SBCI).

Hence, option a is correct.

17. Which of the following have species that can establish a symbiotic relationship with other organisms?

1. Cnidarians

2. Fungi

3. Protozoa

Select the correct answer using the codes given below.

(a) 1 and 2 Only

(b) 2 and 3 Only

(c) 1 and 3 Only

(d) 1, 2 and 3 

17. Ans: d

Explanation:

The term symbiosis was coined in 1879 by Heinrich Anton de Bary, a German mycologist, who defined it as: “the living together of unequally named organisms”. In this broad sense symbiosis includes all kinds of close biological relationships between species, hence spanning a continuum between pathogenic and mutualistic phenomena.  

The term symbiosis is derived from the Greek word for living together, symbiosis refers to a close and prolonged association between 2 or more organisms of different species that may last for the lifetime of 1 or all partners. 

Symbiosis is  prolonged associations between organisms often widely separated phylogenetically.

Symbioses can be mutualistic (all partners benefiting), commensalistic (one benefiting and the others unharmed), or parasitic.

Symbiosis in Cnidarians:

Symbiosis between invertebrates and photosynthetic partners are abundant in the marine environment, with the best known being the mutualism between members of the phylum Cnidaria (e.g., hard and soft corals, sea anemones, jellyfish, and hydrocorals) and dinoflagellate algae of the genus zooxanthellae. These dinoflagellates typically reside within the cells of the host cnidarian’s gastrodermis.

Symbiotic relationship of fungi:

Fungi have several mutualistic relationships with other organisms. 

• Symbiosis of fungi and plants: A mycorrhiza is a mutualistic relationship between a fungus and a plant. The fungus grows in or on the plant roots. The fungus benefits from the easy access to food made by the plant. The plant benefits because the fungus puts out mycelia that helps absorb water and nutrients like phosphorus and nitrogen. 
• Symbiosis of Fungi and Algae: A lichen is an organism that results from a mutualistic relationship between a fungus and a green alga or a fungus and a cynabacterium. The photosynthesizer benefits from the water and nutrients absorbed by the fungus. Lichens are often pioneer species in primary ecological succession. 
• Symbiosis of Fungi and insects: Some fungi have mutualistic relationships with insects. For example: Leafcutter ants grow fungi on beds of leaves in their nests. The fungi get a protected place to live. The ants feed the fungi to their larvae. Ambrosia beetles bore holes in tree bark and “plant” fungal spores in the holes. The holes in the bark give the fungi an ideal place to grow. The beetles harvest fungi from their “garden.”

Symbiosis in Protozoa :

Protozoa are a diverse group of unicellular eukaryotic organisms. Termites have a mutualistic relationship with protists that live in the insects’ gut. The termite benefits from the ability of the protists to digest cellulose. The termite itself cannot do this without the protozoa, it would not be able to obtain energy from its food (cellulose from the wood it chews and eats). The protozoa benefit by having a protective environment and a constant supply of food from the wood-chewing actions of the termite. 

The protists benefit from the enzymes provided by their bacterial endosymbionts, while the bacteria benefit from a doubly protective environment and a constant source of nutrients from two hosts.

Hence, option d is correct.

18. How is permaculture farming different from conventional chemical farming?

1. Permaculture Farming discourages monocultural practices but in conventional chemical farming, monoculture practices are pre-dominant.

2. Conventional chemical farming can cause increase in soil salinity but the occurrence of such phenomenon is not observed in permaculture farming.

3. Conventional chemical farming is easily possible in semi-arid regions but permaculture farming is not so easily possible in such regions.

4. Practice of mulching is very important in permaculture farming but not necessarily so in conventional chemical farming.

Select the correct answer using the codes given below.

a. 1 and 3

b. 1, 2 and 4

c. 4 Only

d. 2 and 3

18. Ans: b

Explanation:

Permaculture as a concept and a movement emerged from combining the words “permanent” and “agriculture.” It was first developed by Bill Mollison and David Holmgren in 1978. It is a polyculture system that supports the diversity of beneficial species like in crop-livestock-agroforestry. There are no fixed methods in permaculture. It follows the principle of producing no waste mimicking the natural pattern of exchange and cycling of matter and energy wherein the output of one element is used as an input for another. 

In a semi-arid landscape, local species that thrive under dry conditions can be planted. In cases of heavy rainfall areas, the crops which soak water are harvested. Thus, a permaculture farm is more sustainable in the face of climate change. That means Permaculture can be effective in harsh climatic conditions like that of Semi-arid regions.

Hence, statement 3 is incorrect.

The practice of permaculture involves ecosystem-centric activities such as restoring the natural nutrient balance of land, ensuring healthy water levels and soil diversity, preventing soil salinity,  generating abundance and diversity of food, and accounting for all inputs and outputs to build a self-sufficient ecosystem ultimately.

Hence, statement 2 is correct.

Permaculture systems, in contrast to monoculture, provide a rich tapestry of plant life that supports a variety of colours, textures, and flavours. This ensures a constant supply of food by reducing the susceptibility of a single crop failing. The interaction of various species creates a balanced habitat in which each component contributes, from providing shade to attracting beneficial insects. 

Hence, statement 1 is correct.

These systems naturally require less labour for maintenance because of smart companion planting, mulching, and creative design. Mulching is a gardening technique that involves covering topsoil with plant material. This material can include leaves, grass, twigs, straw, wood chips, hay, or bark. It helps in preserving moisture, improving soil structure, preventing soil erosion, regulating soil temperature, and enhancing soil organisms. 

Permaculture strengthens agricultural resilience by naturally controlling insect outbreaks and lowering the need for chem ical interventions.

By practicing permaculture farming, the aim is to rewild natural scapes to abundance, build landscape resilience, regenerate soil health, and grow food forests for communities who wish to be in harmony with nature while fulfilling their lifestyle needs.

Hence, statement 4 is correct.

19. In the context of India’s preparation for Climate-smart Agriculture, consider the following statements:

1.The ‘Climate-Smart Village’ approach in India is a part of a project led by the Climate Change, Agriculture and Food Security (CCAFS), an international research programme.

2. The project of CCAFS is carried out under the Consultative Group on International Agricultural Research (CGIAR) headquartered in France.

3. The International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) in India is one of the CGIAR’s research centres.

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

19. Ans:  d

Explanation:

Climate-smart agriculture (CSA) is an integrative approach to address these interlinked challenges of food security and climate change, that explicitly aims for three objectives:

1. Sustainably increasing agricultural productivity
2. Adapting and building resilience of agricultural and food security systems 
3. Reducing greenhouse gas emissions from agriculture (including crops, livestock and fisheries)

Climate-Smart Villages (CSVs), is a participatory international research program of CGIAR  which includes participation from sites ranging from village to district level at which portfolios of CSA interventions are tested in a globally comparable manner with farmers, development agencies and the private sector. The CSV project launched in 2011 with 15 climate-smart villages in West Africa, East Africa and South Asia. Additional villages are now being chosen in Latin America and Southeast Asia. The project is led by Climate Change, Agriculture and Food Security (CCAFS).

Hence, statement 1 is correct.

It is carried out under the Consultative Group on International Agricultural Research (CGIAR) which seeks to address the increasing challenge of global warming and declining food security on agricultural practices. CGIAR is headquartered in France.

Hence, statement 2 is correct.

About CGIAR: 

CGIAR Research Centers are non-profit research organizations conducting innovative research. Home to more than 9,000 scientists, researchers, technicians and staff, the Centers work to transform food, land and water systems in a climate crisis. 

CGIAR Research center in India is the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) in Patancheru, Telangana. CCAFS and CGIAR centers together are engaging with national and sub-national stakeholders including policymakers, NGOs and civil society groups, research organizations, farmers groups and private sector for promotion of climate-smart agriculture in India.

Hence, statement 3 is correct.