UPSC Prelims 2013 Analysis

Explanation

Fungi and Bacteria are decomposers.

• They breakdown organic matter into simple inorganic substances.

• Virus represents dormant life. They are metabolically inactive as long as they are outside a host body.

• They are not decomposers. They invade host cells and use their nucleus (DNA machinery) to carry out their life processes.

Explanation

In India, the largest consumer of water is Agriculture amounting to more than 80% of the total water consumption.

Industrial water consumption is about 1015% of the total.

If we do not consider agriculture as an industry then the highest water consumers are Thermal Power Plants which comprise of 87% of the total industrial water usage or about 812% of the total water consumption. This is because cooling water is a crucial requirement for the thermal power plant. To prevent thermal pollution due to the discharge of heated water, most of the plants have closed loop water cycle. In such a plant, they evaporate the water and force cool it by fans. The water is generally taken from a nearby River or in rare occasions Sea directly via Canal.

Explanation

Arsenic, fluoride, and uranium are naturally occurring elements that can leach into groundwater in some regions of India.

Sorbitol is a sugar alcohol not typically found as a pollutant in drinking water.

Formaldehyde is a synthetic compound used in various industrial processes and is not a common contaminant in groundwater.

Explanation

The Star tortoise, Monitor lizard, and Pygmy Hog are all species that are naturally found in India.

The Star tortoise is a medium-sized species of tortoise found in the dry and arid forests of India.

Monitor lizards are prevalent in India with four kinds occurring Bengal monitor lizard, water monitor lizard, desert monitor lizard, and yellow monitor lizard.

The Pygmy Hog is a critically endangered species that was once found in Bhutan, Nepal, and India but is now only found in India.

However, Spider monkeys are not found in India. They live in tropical climates, specifically the evergreen forests of Central and South America.

Therefore, the correct answer is 1, 2, and 3 only.

Explanation

All the options are correct. The vegetation of hot desert climate is the xerophytic type which has special characteristics to withstand very high rate of evaporation.

• They have long roots, to reach deep water sources.
• Thick barks, to reduce water loss.
• Waxy leaves, to minimize evaporation.
• Presence of thorns and little leaves, to reduce water loss.

Explanation

Nitrogenous Waste products of Living organisms such as urea and uric acid and dead remains of organisms are converted back to inorganic ammonia by the bacteria.

• Animal Waste like Urea, Uric acid and Death of vegetation add nitrogen in the form of nitrates directly into the soil.

• Coal combustion adds nitrogen to the atmosphere and from there it falls back to earth in the form of acid rain and acid rain adds nitrogen to the soil.

Explanation

Acid rain is caused by the pollution of the environment by primarily sulphur dioxide and nitrogen oxides.

These pollutants are released into the atmosphere during the burning of fossil fuels, like coal, for electricity generation and from the exhaust of vehicles.

When they reach the atmosphere, they react with water, oxygen, and other chemicals to form sulphuric and nitric acid, which fall back to Earth as acid rain.

Explanation

Out of the listed elements, the following are released into the environment due to improper e-waste disposal

1. Beryllium
2. Cadmium
3. Chromium
4. Mercury
5. Lead Here's why these elements are found in e-waste and why the others are not

Beryllium, Cadmium, Chromium, Mercury, and Lead These are all heavy metals commonly used in various electronic components like circuit boards, batteries, and monitors. Improper disposal of e-waste can cause these toxic materials to leach into the soil and water, posing environmental and health risks.

Heptachlor This is an organic compound historically used as an insecticide. While it may have been present in some older electronic equipment, it's not a typical component of modern electronics and wouldn't be a major concern in e-waste disposal.

Plutonium This is a radioactive element primarily used in nuclear weapons and reactors. It's not a component of electronic devices and wouldn't be present in e-waste.

So, the answer should not contain 4 and 7.

Explanation

The lion-tailed macaque (Macaca silenus), or the wanderoo, is an Old World monkey endemic to the Western Ghats of South India.

A recent assessment for IUCN reports 3000-3500 of these animals live scattered over several areas in Tamil Nadu, Kerala, Karnataka.

The lion-tailed macaque ranks among the rarest and most threatened primates.

IUCN Status - Endangered.

Silent Valley has the largest number of lion-tailed macaques in South India.

Explanation

The gharial (Gavialis gangeticus), also known as the gavial or fish-eating crocodile, is a crocodilian in the family Gavialidae and is native to the northern part of the Indian subcontinent. As the population has declined drastically since the 1930s, the gharial is listed as Critically Endangered on the IUCN Red List. It once inhabited all the major river systems of the Indian subcontinent, from the Indus River in the west to the Irrawaddy River in the east.

The leatherback sea turtle (Dermochelys coriacea), sometimes called the lute turtle, leathery turtle or simply the luth, is the largest of all living turtles and is the fourth-heaviest modern reptile behind three crocodilians. It is listed as Critically Endangered on the IUCN red list.

The barasingha, also called swamp deer, is a deer species distributed in the Indian subcontinent. Populations in northern and central India are fragmented, and two isolated populations occur in southwestern Nepal. It is listed as Vulnerable on the IUCN red list. It used to be endangered, but conservation efforts have helped improve its status

Explanation

The precipitation is so erratic that drought and fire prevent large forests from growing.

• Grasses can survive fires because they grow from the bottom instead of the top.

• Their stems can grow again after being burned off.

• The soil of most grasslands is also too thin and dry for trees to survive.

Explanation

In ecology, a niche is a term describing the relational position of a species or population in an ecosystem.

More formally, the niche includes how a population responds to the abundance of its resources and enemies (e.g., by growing when resources are abundant, and predators, parasites, and pathogens are scarce) and how it affects those same factors (e.g., by reducing the abundance of resources through consumption and contributing to the population growth of enemies by falling prey to them).

Gause's competitive exclusion principle says that those species having identical requirements cannot occupy the same niche indefinitely.

Explanation

Food chain, in ecology, is the sequence of transfers of matter and energy in the form of food from organism to organism.

• Food chains are not found within the populations of a species, because technically, the food chain is the sequence of organisms through which the energy flows.

• Food chains intertwine locally into a food web because most organisms consume more than one type of animal or plant.

Explanation

Ramganga River (not the Ganga River) passes through Jim Corbett National Park, located in Uttarakhand state, which is the oldest national park of India.

Kaziranga in Aasam is a vast stretch of tall elephant grass, marshland and dense tropical moist broadleaf forests crisscrossed by four main rivers Brahmaputra, Diphlu, Mora Diphlu and Mora Dhansiri and has numerous small water bodies.

The Kunthipuzha River passes through the Silent Valley National Park, located in the Kerala state.

Thus, no pair is correctly matched.

Explanation

Out of the listed pairs, only Nokrek Biosphere Reserve is correctly matched to Garo Hills.

Nokrek Biosphere Reserve This is situated in the Garo Hills of Meghalaya.

Logtak (Loktak) Lake This freshwater lake(famous for Phumdis) is located in Manipur, not the Barail Range (which is a mountain range in Assam).

Namdapha National Park This national park is indeed found in Arunachal Pradesh, but not specifically in the Dafla Hills region. It's on the eastern border with Myanmar.

Explanation

The correct sequence of ecosystems in order of decreasing productivity is

1. Mangroves > 2. Grasslands > 3. Lakes > 4. Oceans

Mangroves These coastal ecosystems boast exceptionally high productivity due to several factors. They receive rich nutrients from both land and sea, have a warm climate, and benefit from tidal flushing that brings in fresh nutrients and removes waste products.

Grasslands These moderate-productivity ecosystems are characterized by abundant grasses and herbaceous plants. Their productivity depends on factors like rainfall, soil quality, and grazing pressure.

Lakes Freshwater lakes exhibit varying levels of productivity depending on the nutrient availability (oligotrophic - nutrient-poor, eutrophic - nutrient-rich). Generally, they are less productive than mangroves and grasslands.

Oceans Marine ecosystems, particularly open oceans, have the lowest overall productivity. Nutrient availability is limited in vast stretches of the ocean, leading to a slower rate of organic matter production compared to the other ecosystems listed.

Explanation

Out of the three organisms listed, only 2. Nostoc is commonly used as a biofertilizer.

Agaricus This is a type of mushroom and not typically used as a biofertilizer.

Nostoc This is a filamentous, nitrogen-fixing cyanobacterium. Cyanobacteria, also known as blue-green algae, are one of the main groups of organisms used in biofertilizers due to their ability to fix atmospheric nitrogen and make it available to plants.

Spirogyra This is a green alga and not generally used as a biofertilizer.

Explanation

The correct answer is Nitrogen Dioxide, Ozone, and peroxyacetyl nitrate in the presence of sunlight.

Nitrogen Dioxide Released mainly from vehicle exhaust and industrial emissions.

Sunlight Sunlight's energy initiates the chemical reactions that form smog.

Volatile Organic Compounds These are released from gasoline, paints, solvents, and other sources. They react with NO2 in the presence of sunlight.

Ozone Ground-level ozone is a major component of photochemical smog, created by the reactions between NO2 and VOCs. Peroxyacetyl Nitrate (PAN) PAN is another harmful component of smog, formed in the same reactions.

The simplified process Sunlight triggers reactions between Nitrogen Dioxide and VOCs, leading to the formation of ozone, PAN, and other noxious components of photochemical smog.

Explanation

Contour Bunding is associated with terracing, to check the flow of water on a hill slope in order to reduce soil erosion. This method is crucial for preventing soil erosion and is a part of sustainable land management practices.