Environment & Ecology Previous Year Questions (PYQ) with Answers – Page 2

The correct answer is A, The International Union for Conservation of Nature. The Invasive Species Specialist Group (ISSG) is one of the expert groups of the IUCN's Species Survival Commission, and it manages the Global Invasive Species Database. The ISSG is a network of scientists and policy experts that gathers information on alien species that spread and harm native wildlife, and it also compiled the well-known list of '100 of the World's Worst Invasive Alien Species'. The IUCN, founded in 1948 and based at Gland in Switzerland, also publishes the Red List of Threatened Species. Invasive plants such as Lantana, water hyacinth and Prosopis juliflora are a major threat to Indian forests and wetlands. Option B is wrong because UNEP runs environmental programmes and conventions but not this specialist group. Option C is wrong because the World Commission on Environment and Development, the Brundtland Commission, is known for its 1987 report 'Our Common Future'. Option D is wrong because WWF is a separate conservation NGO. Exam tip: IUCN means the Red List, the Species Survival Commission and the invasive species database.

The correct answer is B, By increasing the efficiency of the combustion process. When coal, petrol or diesel burn with too little oxygen, the burning is incomplete and gives out carbon monoxide, soot and unburnt hydrocarbons, the worst pollutants from vehicles and power plants. Efficient, complete combustion turns more of the fuel into carbon dioxide and water and also gets more energy from each litre or kilogram, so less fuel has to be burnt. Catalytic converters in vehicles, which change carbon monoxide and nitrogen oxides into less harmful gases, and cleaner fuels such as CNG work on the same idea. A is wrong because lowering the burning temperature leads to incomplete combustion and more smoke and carbon monoxide. C is wrong because adding more carbon only means more carbon dioxide and more soot. D is wrong because latent heat is the heat needed to change the state of a substance, such as ice to water, and has nothing to do with pollution from burning. Exam tip: complete combustion gives CO2 and water; incomplete combustion gives carbon monoxide and soot.

The correct answer is D, 1866. The German zoologist Ernst Haeckel coined the word 'Oekologie' in 1866 in his book Generelle Morphologie der Organismen. He built it from the Greek oikos, meaning house or household, and logos, meaning study, so ecology is the study of living things in their home, their relations with each other and with their surroundings. That is why the question speaks of the 'economies' of living forms, since economy comes from the same oikos. Haeckel was a strong supporter of Darwin and also gave biology words such as phylum. A related date that papers test is 1935, when the British ecologist A. G. Tansley coined the term 'ecosystem'. A is wrong because 1888 has no link with the word; by then it had been in use for over twenty years. B is wrong because 1884 is also too late and is not a date tied to ecology's naming. C is wrong because 1887 is likewise unconnected with Haeckel's coinage. Exam tip: ecology by Haeckel in 1866, ecosystem by Tansley in 1935.

The correct answer is A, 1 only. Statement 1 is true and statement 2 is false. Race to Zero is a global campaign backed by the United Nations and launched in 2020, ahead of the COP26 climate talks in Glasgow. It rallies businesses, cities, regions, investors and universities to take rigorous action to halve global emissions by 2030 and reach net-zero emissions by 2050 at the latest, in line with the Paris Agreement aim of limiting warming to 1.5 degrees Celsius. Building momentum for a shift to a decarbonised economy is exactly its aim, so statement 1 is correct. Statement 2 is wrong: the zero in the name means net-zero carbon emissions, not a zero-sum game, where one side's gain equals the other side's loss; climate action is meant to benefit everyone. B is wrong, because statement 2 is the false one. C is wrong, because it accepts the false zero-sum statement. D is wrong, because statement 1 correctly describes the campaign. Exam tip: Race to Zero, UN-backed, 2020, halve emissions by 2030, net zero by 2050.

The correct answer is A, 1%. Green plants are the producers of a terrestrial ecosystem, and NCERT's Class 10 chapter Our Environment states that they capture about 1 percent of the energy of the sunlight that falls on their leaves and convert it into food energy through photosynthesis. The rest of the sunlight is reflected, passes through the leaf or is lost as heat. This tiny fraction is the base of every food chain, and only about 10 percent of it passes from one trophic level to the next, which is Lindeman's ten percent law; that is why food chains rarely have more than three or four steps and why energy flow in an ecosystem is unidirectional. B, 5%, C, 8%, and D, 10%, are all too high: 10 percent is the share of energy transferred between trophic levels, not the share of sunlight captured by plants, and students often mix up these two numbers. Exam tip: plants capture about 1 percent of sunlight; about 10 percent of energy moves up at each trophic level.

The correct answer is B, Oxygen. A greenhouse gas is one whose molecules absorb the long-wave infrared radiation given off by the warm surface of the Earth and send part of it back, keeping the planet about 33 degrees Celsius warmer than it would otherwise be. Such absorption needs molecules made of three or more atoms, or of two different atoms, that can vibrate in the right way. Oxygen (O2) and nitrogen (N2), which together make up 99 percent of the air, are made of two identical atoms, do not absorb infrared radiation and therefore are not greenhouse gases, even though they are the most abundant gases. A, Water vapour, is the largest natural contributor to the greenhouse effect. C, Carbon dioxide, is the main greenhouse gas added by humans through burning coal, oil and gas, and it is the reference gas for global warming potential. D, Methane, traps about 28 times more heat than carbon dioxide over a century and comes from paddy fields, cattle and landfills. Exam tip: the main greenhouse gases are water vapour, CO2, methane, nitrous oxide, ozone and CFCs; N2 and O2 are not.

The correct answer is C, Gir Forest. Gir in Gujarat is a national park and wildlife sanctuary, famous as the only home of the Asiatic lion, but it has never been declared a biosphere reserve. A biosphere reserve is a much larger area, notified under UNESCO's Man and the Biosphere programme, with a protected core zone, a buffer zone and a transition zone where people live and work. India's list began with the Nilgiri in 1986, and Panna in Madhya Pradesh, added in 2011, was the eighteenth. A is wrong because the Cold Desert biosphere reserve was set up in 2009 in the Lahaul-Spiti region of Himachal Pradesh. B is wrong because the Sunderbans in West Bengal, home of the Royal Bengal tiger and the mangroves, became a biosphere reserve in 1989 and is on the UNESCO world network. D is wrong because the Nilgiri biosphere reserve, spread over Tamil Nadu, Kerala and Karnataka, was India's first, declared in 1986. Exam tip: Nilgiri first (1986), Sunderbans 1989, Cold Desert 2009; Gir = lions, national park, not a biosphere reserve.

The correct answer is A, Cold Desert. The Cold Desert Biosphere Reserve in the Lahaul and Spiti region of Himachal Pradesh was notified in 2009 as India's 16th biosphere reserve. It covers the Pin Valley National Park, the Kibber Wildlife Sanctuary and the high-altitude wetlands of Chandratal and Sarchu, a trans-Himalayan landscape above 3,000 metres that gets very little rain. Its wildlife includes the snow leopard, Himalayan ibex, red fox, blue rock pigeon and the lammergeier or bearded vulture, the bird that drops bones from a height to eat the marrow. Option B is wrong because Seshachalam, in Andhra Pradesh and famous for red sanders, followed in 2010 as the 17th reserve. Option C is wrong because Agasthyamalai, on the Kerala and Tamil Nadu border, was notified in 2001. Option D is wrong because Dehang-Debang in Arunachal Pradesh dates from 1998. Exam tip: the sequence at the end of the list is Cold Desert 2009 (16th), Seshachalam 2010 (17th), Panna 2011 (18th); the first was Nilgiri in 1986.

The correct answer is A, Tsunami. A tsunami is caused by an undersea earthquake, a volcanic eruption or a landslide on the ocean floor, and has nothing to do with the ozone layer.

The ozone layer lies in the stratosphere, roughly 15 to 35 km above the ground, and absorbs most of the harmful ultraviolet radiation of the Sun. Chlorofluorocarbons used in refrigerators, air conditioners and aerosol sprays release chlorine that destroys ozone, which is why the Montreal Protocol of 1987 phased them out. World Ozone Day is observed on 16 September.

Option B is a real result, because extra ultraviolet radiation damages skin cells and raises the risk of skin cancer. Option C is a real result, since a thinner layer lets more ultraviolet rays reach the Earth. Option D is a real result, as ultraviolet exposure weakens the immune system, and it also causes cataract and harms crops and plankton.

Exam tip: ozone holes bring skin cancer, cataract and weak immunity; tsunamis come from the sea floor, not the sky.

The correct answer is A, 5 NTU. Under the Bureau of Indian Standards specification for drinking water, IS 10500:2012, turbidity has an acceptable limit of 1 NTU and a maximum permissible limit of 5 NTU in the absence of any alternate source. Turbidity is the cloudiness of water caused by suspended clay, silt and organic matter, and it is measured in nephelometric turbidity units by how much light a sample scatters sideways. It is kept low because suspended particles shelter bacteria and viruses from chlorine and make disinfection less effective. Option B is wrong because 1 NTU is the acceptable limit, not the maximum permissible one. Option C is wrong because 3 NTU appears in neither column of the standard. Option D is wrong because 7 NTU is above what the standard allows in any circumstance. Exam tip: for IS 10500:2012 remember the pair — turbidity acceptable 1 NTU and permissible 5 NTU, with pH held between 6.5 and 8.5.

The correct answer is D, Tamil Nadu. Tamil Nadu is the first state in India to make rooftop rainwater harvesting structures compulsory for all houses and buildings across the state, through a law brought in 2003. The state depends heavily on the north-east monsoon and on groundwater, and Chennai faced severe water shortages, so collecting roof water and sending it into the ground became a priority. Rooftop harvesting collects rain from roofs and stores it in tanks or uses it to recharge wells and aquifers, which raises the water table. Option A is wrong because Kerala gets heavy rain and has promoted harvesting, but it was not the first to make it compulsory for every house. Option B is wrong because Gujarat is known for check dams and other water works, not for this first law. Option C is wrong because Rajasthan is known for traditional harvesting, such as the tankas of Bikaner and Phalodi, not for the first statewide law. Exam tip: Tamil Nadu was the first state to make rooftop rainwater harvesting compulsory (2003); tankas are Rajasthan's traditional underground tanks.

The correct answer is C, Kachchh. The Kachchh Biosphere Reserve in Gujarat, notified in 2008, covers about 12,454 square kilometres and is the largest biosphere reserve in India by area. It takes in the Great Rann and the Little Rann of Kachchh, salt marshes that flood in the monsoon, and is home to the Indian wild ass, the flamingo breeding grounds and the desert fox. The first biosphere reserve of India was the Nilgiri Biosphere Reserve, set up in 1986 across Tamil Nadu, Kerala and Karnataka. A is wrong because the Sundarbans reserve in West Bengal covers about 9,630 square kilometres. B is wrong because the Gulf of Mannar reserve in Tamil Nadu is about 10,500 square kilometres. D is wrong because Nanda Devi in Uttarakhand is about 5,860 square kilometres. Exam tip: largest biosphere reserve by area = Kachchh (Gujarat); first = Nilgiri (1986); do not confuse it with the largest national park, Hemis in Ladakh.

The correct answer is A, Refuse. The 3 R's of waste management are Reduce, Reuse and Recycle; Refuse is not one of them. Reduce means creating less waste in the first place, such as buying fewer packaged goods and switching off lights to save power. Reuse means using a thing again, like refilling a bottle or turning old clothes into bags. Recycle means sending waste such as paper, glass, metal and plastic to be made into new products. NCERT gives the three in this order, and the order matters: reducing is the best option and recycling the last resort because it still uses energy. Some newer lists add Refuse and Repurpose to make 5 R's, but the paper asks about the 3 R's. B is wrong because recycling is one of the three. C is wrong because reducing is the first R. D is wrong because reuse is the second R. Exam tip: 3 R's = Reduce, Reuse, Recycle, in that order of preference.

The correct answer is D, stratification. It means the layering of an ecosystem from top to bottom, with each layer holding its own set of species. The NCERT example is a forest: tall trees form the top layer, shrubs the second, and herbs and grasses the bottom layer, and each layer gets a different amount of light, heat and moisture. A tropical rainforest shows the most layers, with emergent trees, the canopy, the understorey and the forest floor, and animals such as birds, monkeys and insects also live at particular heights. Lakes are stratified too, into a warm upper layer and a cold bottom layer. Stratification lets many species share the same patch of land without competing directly. A is wrong because levelling is not a term used in ecology for vertical layers. B is wrong because grouping simply means putting things together and says nothing about height. C is wrong because ramification means branching and describes how a plant spreads, not layers of species. Exam tip: vertical layering in an ecosystem is stratification; trees, shrubs, herbs from top to bottom.

The correct answer is D, Andhra Pradesh. The Seshachalam Biosphere Reserve lies in the Seshachalam hill ranges of the Eastern Ghats in southern Andhra Pradesh, across the old Chittoor and Kadapa districts, and was notified in 2010 as India's 17th biosphere reserve. The Tirumala temple of Lord Venkateswara stands on these very hills, and the reserve includes the Sri Venkateswara National Park. It is famous for red sanders, the valuable red-wood tree found almost nowhere else in the world, and shelters the slender loris, the golden gecko and the Indian giant squirrel. Option A is wrong because Tamil Nadu's biosphere reserves are the Gulf of Mannar and its shares of the Nilgiri and Agasthyamalai reserves. Option B is wrong because Karnataka's only biosphere reserve is its part of the Nilgiri. Option C is wrong because Kerala shares the Nilgiri and Agasthyamalai reserves but has no Seshachalam. Exam tip: Seshachalam = Andhra Pradesh, red sanders, Tirumala hills, notified 2010 as the 17th reserve.

The correct answer is A, 1982. The Ramsar Convention came into force for India on 1 February 1982, the date on which India's accession took effect. The treaty itself was signed on 2 February 1971 in the Iranian city of Ramsar, on the Caspian Sea, and came into force internationally in 1975; 2 February is therefore observed as World Wetlands Day. It is the only global convention devoted to one type of ecosystem, and sites listed under it are called Ramsar sites or Wetlands of International Importance. India's first two, Chilika Lake in Odisha and Keoladeo National Park in Rajasthan, were designated on 1 October 1981, just before the convention took effect for the country. So keep three years apart: 1971 signed, 1975 in force worldwide, 1982 in force for India. B, 1980, is the year of the Forest (Conservation) Act, not Ramsar. C, 1989, and D, 1990, have no link with the convention in India. Exam tip: Ramsar 1971, wetlands, Iran; India joined 1982; Chilika and Keoladeo were first.

The correct answer is C, methane and carbon dioxide. Biogas is produced when cattle dung, crop waste and sewage are broken down by bacteria in a closed tank without air, a process called anaerobic digestion. The gas that collects is about 55 to 70 per cent methane and most of the rest is carbon dioxide, with small traces of hydrogen sulphide and water vapour. Methane is the part that burns, which is why biogas gives a clean blue flame and is used for cooking and lighting in villages; the slurry left behind is a good manure. A gobar gas plant thus turns waste into fuel and fertiliser at the same time. A is wrong because hydrogen is not a major part of biogas. B is wrong because helium is an inert gas that no bacteria produce. D is wrong because nitrogen is present only in traces and does not burn. Exam tip: biogas is mainly methane with carbon dioxide, made by anaerobic digestion, and its slurry is used as manure.

The correct answer is B, Pinjore. India's first vulture breeding centre, the Jatayu Conservation Breeding Centre, was set up at Pinjore in the Panchkula district of Haryana in 2001. It was started because the population of white-backed, long-billed and slender-billed vultures had crashed by more than ninety per cent in the 1990s. The cause was diclofenac, a painkiller given to cattle, which caused kidney failure in vultures that fed on the carcasses; its veterinary use was banned in India in 2006. The centre breeds these three critically endangered species in captivity and releases them into the wild. Option A is wrong because Pushkar in Rajasthan is known for its lake and the Brahma temple. Option C is wrong because Rampur in Uttar Pradesh has no such centre, though a vulture centre works at Rani in Assam. Option D is wrong because Agra is known for the Taj Mahal and a bear rescue facility. Exam tip: Pinjore in Haryana for vultures, and diclofenac as the reason for their decline.

The correct answer is B, Marine. In the sea the producers are tiny phytoplankton. At any given moment their total mass is smaller than the mass of the zooplankton and fish that feed on them, so the pyramid of biomass stands upside down. This happens because phytoplankton grow and divide very fast and are eaten almost as quickly as they are produced, so a small standing crop can support a larger mass of consumers. The pyramid of energy, however, is always upright in every ecosystem, because energy is lost as heat at each step and only about 10 percent passes to the next level. Option A is wrong because in a grassland the grasses far outweigh the grazing animals, giving an upright pyramid. Option C is wrong because the tundra also has more plant mass than animal mass. Option D is wrong because in a forest the huge trees give a large biomass base, so the pyramid of biomass is upright, even though the pyramid of numbers there can be inverted. Exam tip: numbers can be inverted in a tree ecosystem, biomass in the sea, but energy never.

The correct answer is C, 1, 3 and 5 only. Earthworms, millipedes and woodlice feed on dead plant and animal matter, called detritus, so they are detritivores. Detritivores break dead leaves and bodies into small pieces, which speeds up the work of decomposers such as bacteria and fungi that finish the breakdown and return nutrients to the soil. Earthworms eat decaying leaves and soil, millipedes chew leaf litter on the forest floor, and woodlice are small land crustaceans that live under logs and eat rotting wood. The key difference is that detritivores swallow detritus, while decomposers digest it outside their bodies. Jellyfish (2) are wrong because they are carnivores that sting and eat plankton and small fish. Seahorses (4) are wrong because they suck in tiny live crustaceans. So options A, B and D, which include jellyfish or seahorses, are wrong. Exam tip: earthworms, millipedes, woodlice and dung beetles are detritivores; bacteria and fungi are decomposers.