UPSC IAS Archives

41. With reference to food chains in ecosystems, consider the following st

With reference to food chains in ecosystems, consider the following statements:

1. A food chain illustrates the order in which a chain of organisms feed upon each other.
2. Food chains are found within the populations of a species.
3. A food chain illustrates the numbers of each organism which are eaten by others.

Which of the statements given above is/are correct?

1 only

1 and 2 only

1, 2 and 3

None

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Statement 1 is correct. A food chain shows the linear sequence of organisms where nutrients and energy are transferred as one organism eats another. Statements 2 and 3 are incorrect.

A food chain illustrates the trophic relationships between different species in an ecosystem, showing the flow of energy from producers to consumers of various levels. Food chains involve interactions *between* different species at different trophic levels, not typically *within* the population of a single species (unless referring to cannibalism, which isn’t the primary representation). While the number of organisms at each level can be represented in an ecological pyramid (like the pyramid of numbers), a simple food chain diagram does not illustrate the *numbers* of organisms eaten.

Ecosystems consist of multiple interconnected food chains, forming a food web. Food chains help understand the flow of energy and the impact of changes in one trophic level on others.

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42. Acid rain is caused by the pollution of environment by

Acid rain is caused by the pollution of environment by

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carbon dioxide and nitrogen

carbon monoxide and carbon dioxide

ozone and carbon dioxide

nitrous oxide and sulphur dioxide

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The correct answer is D) nitrous oxide and sulphur dioxide.

Acid rain is primarily caused by atmospheric pollutants, mainly sulfur dioxide (SO₂) and nitrogen oxides (NOx). These gases are released into the atmosphere, primarily from the burning of fossil fuels. In the atmosphere, they react with water, oxygen, and other chemicals to form sulfuric and nitric acids. These acids then fall to the Earth’s surface through rain, snow, fog, or dry deposition. While the term “nitrous oxide” (N₂O) is specifically mentioned in the option, it is one of the nitrogen oxides (NOx) group, although NO and NO₂ from combustion are the main contributors to acid rain’s nitrogen component. However, compared to other options which list substances not responsible for acid rain (Carbon dioxide, Carbon monoxide, Ozone, Nitrogen), this option correctly identifies the two major categories of pollutants that lead to acid rain (sulfur compounds and nitrogen compounds).

Sulfur dioxide emissions largely come from power plants and industrial facilities burning coal and oil. Nitrogen oxide emissions come from vehicle exhausts, power plants, and industrial combustion. Acid rain has harmful effects on ecosystems, damaging forests, lakes, buildings, and monuments.

43. Due to improper/indiscriminate disposal of old and used computers or t

Due to improper/indiscriminate disposal of old and used computers or their parts, which of the following are released into the environment as e-waste?

1. Beryllium

2. Cadmium

3. Chromium

4. Heptachlor

5. Mercury

6. Lead

7. Plutonium

Select the correct answer using the codes given below.

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1, 3, 4, 6 and 7 only

1, 2, 3, 5 and 6 only

2, 4, 5 and 7 only

1, 2, 3, 4, 5, 6 and 7

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The correct answer is B) 1, 2, 3, 5 and 6 only.

Electronic waste (e-waste), such as old computers and their parts, contains various hazardous substances. The list provided includes several heavy metals commonly found in electronic components: Beryllium (1), Cadmium (2), Chromium (3, often hexavalent chromium), Mercury (5), and Lead (6). These substances pose significant environmental and health risks if not disposed of properly. Heptachlor (4) is an organochlorine pesticide, not a standard component of electronics. Plutonium (7) is a radioactive element associated with nuclear materials, not found in typical consumer electronics. Therefore, 1, 2, 3, 5, and 6 are commonly released into the environment from improper e-waste handling.

Other hazardous substances found in e-waste include brominated flame retardants (BFRs), polychlorinated biphenyls (PCBs – in older equipment), and various other chemicals in plastics and circuit boards. Proper e-waste management involves recycling and safe disposal methods to prevent these toxins from contaminating soil, water, and air.

44. ‘Economic Justice’ as one of the objectives of the Indian Constitution

‘Economic Justice’ as one of the objectives of the Indian Constitution has been provided in

the Preamble and the Fundamental Rights

the Preamble and the Directive Principles of State Policy

the Fundamental Rights and the Directive Principles of State Policy

None of the above

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The correct answer is B) the Preamble and the Directive Principles of State Policy.

The Preamble of the Indian Constitution explicitly lists “Justice, social, economic and political” as one of the core objectives to be secured for all citizens. The Directive Principles of State Policy (Part IV of the Constitution) contain detailed provisions that guide the state in making laws and policies aimed at achieving these objectives, particularly social and economic justice. Articles like 38, 39, 41, 42, 43, and 47 embody the state’s commitment to ensuring economic justice through policies related to distribution of wealth, adequate means of livelihood, equal pay for equal work, right to work, education, public assistance, living wage, etc. While Fundamental Rights protect individuals and have indirect economic implications (e.g., right against exploitation), the positive concept of ‘Economic Justice’ as a directive principle for state policy is primarily enshrined in the Preamble and elaborated in the DPSPs.

Fundamental Rights are justiciable and primarily negative injunctions against the state, ensuring basic civil and political liberties. Directive Principles, on the other hand, are non-justiciable guidelines for the state to achieve socio-economic ideals, including economic justice. The Preamble serves as an introduction and lays down the fundamental values and philosophy of the Constitution, including the commitment to economic justice.

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45. Improper handling and storage of cereal grains and oilseeds result in

Improper handling and storage of cereal grains and oilseeds result in the production of toxins known as aflatoxins which are not generally destroyed by normal cooking process. Aflatoxins are produced by

bacteria

protozoa

moulds

viruses

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The correct answer is C) moulds.

Aflatoxins are naturally occurring mycotoxins that are produced by certain molds, specifically species of *Aspergillus*, most notably *Aspergillus flavus* and *Aspergillus parasiticus*. These molds grow on various food crops, such as maize, peanuts, cottonseed, and tree nuts, often under conditions of high humidity and temperature and improper storage. Aflatoxins are highly toxic and carcinogenic, and are not typically destroyed by normal cooking temperatures.

Aflatoxin contamination is a significant concern for food safety, particularly in tropical and subtropical regions. Exposure to aflatoxins can cause acute liver damage and is a major risk factor for liver cancer. Regulatory limits for aflatoxins in food and feed are set by many countries to protect public health.

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46. Under the Scheduled Tribes and Other Traditional Forest Dwellers (Reco

Under the Scheduled Tribes and Other Traditional Forest Dwellers (Recognition of Forest Rights) Act, 2006, who shall be the authority to initiate the process for determining the nature and extent of individual or community forest rights or both?

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State Forest Department

District Collector/Deputy Commissioner

Tahsildar/Block Development Officer/Mandal Revenue Officer

Gram Sabha

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The correct answer is D) Gram Sabha.

According to the Scheduled Tribes and Other Traditional Forest Dwellers (Recognition of Forest Rights) Act, 2006 (FRA), the Gram Sabha is designated as the primary authority responsible for initiating the process of determining the nature and extent of individual or community forest rights within its jurisdiction. Claims for forest rights are first submitted to the Gram Sabha, which verifies them and passes a resolution before forwarding them to higher-level committees (Sub-Divisional Level Committee and District Level Committee) for further verification and final approval.

The FRA emphasizes the role of the Gram Sabha as the most local and democratic body in recognizing and vesting forest rights, ensuring community participation and control over the process. This structure is intended to empower forest-dwelling communities and ensure that the recognition of rights is based on local knowledge and verification.

47. The Government enacted the Panchayat Extension to Scheduled Areas (PES

The Government enacted the Panchayat Extension to Scheduled Areas (PESA) Act in 1996. Which one of the following is not identified as its objective?

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To provide self-governance

To recognize traditional rights

To create autonomous regions in tribal areas

To free tribal people from exploitation

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The correct answer is C) To create autonomous regions in tribal areas.

The Panchayat (Extension to Scheduled Areas) Act, 1996 (PESA) aims to extend the provisions of Part IX of the Constitution relating to Panchayats to the Scheduled Areas, recognizing and incorporating tribal traditions and customary laws. Its key objectives include enabling tribal self-governance through Gram Sabhas, preserving tribal traditions, recognizing community rights over resources, and protecting tribal populations from exploitation. PESA empowers Gram Sabhas significantly but does not create new, separate “autonomous regions” in the sense of distinct administrative entities with legislative powers akin to those under the Sixth Schedule. It rather integrates enhanced self-governance mechanisms within the existing state framework for Scheduled Areas.

PESA gives powers to the Gram Sabha over aspects like land alienation, management of minor forest produce, control over minor water bodies, approval of development plans, and control over local markets and money lending. These powers are intended to ensure tribal self-rule and protect their rights and resources, but the framework remains within the state’s jurisdiction, unlike areas governed by autonomous councils under the Sixth Schedule which have greater administrative and legislative autonomy.

48. Contour bunding is a method of soil conservation used in

Contour bunding is a method of soil conservation used in

desert margins, liable to strong wind action

low flat plains, close to stream courses, liable to flooding

scrublands, liable to spread of weed growth

None of the above

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The correct answer is D) None of the above.

Contour bunding is a soil conservation practice applied on gently sloping land. It involves constructing narrow-based bunds (embankments) along the contour lines. The purpose is to intercept and slow down water runoff, reduce soil erosion, and promote infiltration of water into the soil. This method is particularly effective in semi-arid areas for moisture conservation. The conditions described in options A, B, and C do not match the primary application of contour bunding. Option A describes desert margins prone to wind erosion. Option B describes low flat plains prone to flooding, where different flood control measures are used. Option C describes scrublands and weed growth, not directly addressed by contour bunding.

Contour bunding is typically implemented on agricultural fields, pastures, or other land with slopes ranging from around 2% to 10-15%. It is a key technique in watershed management and dryland farming to improve water retention and prevent loss of fertile topsoil due to water erosion.

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49. Which one of the following is the correct sequence of ecosystems in th

Which one of the following is the correct sequence of ecosystems in the order of decreasing productivity?

Oceans, lakes, grasslands, mangroves

Mangroves, oceans, grasslands, lakes

Mangroves, grasslands, lakes, oceans

Oceans, mangroves, lakes, grasslands

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The correct answer is C) Mangroves, grasslands, lakes, oceans.

Primary productivity refers to the rate at which energy is converted by photosynthetic organisms into organic substances. Among the given options, mangrove ecosystems, being highly productive coastal environments rich in nutrients and sunlight, generally exhibit the highest net primary productivity. Grasslands have moderate productivity, varying significantly based on rainfall and soil fertility. Lakes vary widely from oligotrophic (low productivity) to eutrophic (high productivity), but generally have lower average productivity than highly productive terrestrial or coastal systems. Open oceans, especially the vast pelagic zones, are often nutrient-limited and have relatively low average productivity, although coastal upwelling zones can be highly productive.

The generalized order of decreasing productivity among major ecosystems is often cited as: Tropical rainforests, Swamps and Marshes (including Mangroves), Estuaries > Temperate forests, Cultivated land > Grasslands, Lakes and Streams > Tundra, Open Ocean > Deserts. Comparing the specific options given, mangroves are known for very high productivity, followed by grasslands (moderate), then lakes (variable but often moderate to low), and finally open oceans (generally low). Thus, the sequence of decreasing productivity is typically Mangroves > Grasslands > Lakes > Oceans.

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50. In the grasslands, trees do not replace the grasses as a part of an ec

In the grasslands, trees do not replace the grasses as a part of an ecological succession because of

insects and fungi

limited sunlight and paucity of nutrients

water limits and fire

None of the above

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The correct answer is C) water limits and fire.

In many grassland ecosystems, the primary environmental factors that prevent the establishment and growth of trees, thus maintaining the dominance of grasses in ecological succession, are limited water availability (seasonal droughts, low rainfall) and frequent fires (natural or human-caused). Grasses are well-adapted to these conditions, with deep root systems that survive drought and ability to quickly regrow after fire, whereas young trees are often killed by lack of water or fire.

Ecological succession is the process by which the mix of species and habitat in an area changes over time. In a typical succession sequence in a region capable of supporting forests, grassland might be a transitional stage before shrubland and then forest. However, specific environmental regimes like drought and fire can create “climax communities” like grasslands where forest does not develop. While other factors like grazing can also influence grasslands, water limits and fire are fundamental abiotic factors that often define this biome.

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