Pariksha SaathiGeneral Studies
Environment and Ecology: Practice Questions with Answers
237 practice questions on Environment and Ecology, with answers; most also have an explanation or a worked solution. Try each one before you open its answer.
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Q.101
In an ecosystem where a single large tree supports thousands of insects feeding on it, which ecological pyramid is inverted?
- A Pyramid of numbers
- B Pyramid of biomass
- C Pyramid of energy
- D Pyramid of productivity
Show answer
Correct answer: (A) Pyramid of numbers
One tree (the producer) supports a far larger number of insects, so the pyramid of numbers is inverted. The tree still outweighs the insects in biomass, and the pyramid of energy is always upright.
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Q.102
Shola forests, patches of stunted evergreen forest separated by rolling grasslands, are characteristic of the high-altitude areas of the
- A Aravalli Range
- B Eastern Himalaya
- C Southern Western Ghats (Nilgiri, Anamalai and Palani hills)
- D Chota Nagpur Plateau
Show answer
Correct answer: (C) Southern Western Ghats (Nilgiri, Anamalai and Palani hills)
The shola-grassland mosaic is found in the upper reaches of the southern Western Ghats, mainly in Kerala and Tamil Nadu; the sholas grow in sheltered valleys and help feed streams.
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Q.103
The National Board for Wildlife, constituted under the Wildlife (Protection) Act 1972, is chaired by
- A The President
- B The Union Minister of Environment
- C The Prime Minister
- D The Chief Justice of India
Show answer
Correct answer: (C) The Prime Minister
The National Board for Wildlife, the apex advisory body on wildlife matters, is headed by the Prime Minister, with the Union Minister in charge of forests and wildlife as Vice-Chairperson. Its Standing Committee examines proposals affecting protected areas.
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Q.104
Which invasive aquatic weed, native to South America, is called the 'Terror of Bengal' because it chokes water bodies and depletes their oxygen?
- A Water hyacinth (Eichhornia crassipes)
- B Lantana camara
- C Parthenium (carrot grass)
- D Hydrilla
Show answer
Correct answer: (A) Water hyacinth (Eichhornia crassipes)
Water hyacinth, brought to India as an ornamental plant, spreads so fast that it covers ponds and lakes and harms fish and other aquatic life. Lantana and Parthenium are invasive land weeds.
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Q.105
The introduction of the Nile perch, a large predatory fish, led to the extinction of more than 200 species of cichlid fish in
- A Lake Baikal
- B Lake Victoria
- C Lake Titicaca
- D Lake Superior
Show answer
Correct answer: (B) Lake Victoria
Lake Victoria in East Africa lost a unique assemblage of cichlid fishes after the Nile perch was introduced, a textbook example of biodiversity loss caused by an alien species invasion.
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Q.106
The lion-tailed macaque, a primate with a silver-white mane, is endemic to the
- A Eastern Ghats
- B Western Ghats
- C Eastern Himalaya
- D Andaman Islands
Show answer
Correct answer: (B) Western Ghats
The lion-tailed macaque lives only in the tropical evergreen rainforests of the Western Ghats in Kerala, Karnataka and Tamil Nadu; Silent Valley National Park is one of its strongholds.
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Q.107
Organisms that live on or in the bottom sediments of a lake or sea, such as snails, worms and crabs, are collectively called
- A Plankton
- B Nekton
- C Neuston
- D Benthos
Show answer
Correct answer: (D) Benthos
Benthos live at the bottom, plankton drift with water currents, nekton such as fish swim actively, and neuston live at the water surface.
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Q.108
DDT that builds up in fish-eating birds harms their populations mainly by
- A Making their feathers fall off
- B Blinding the adult birds
- C Making them migrate earlier
- D Causing thin eggshells that break before the chicks hatch
Show answer
Correct answer: (D) Causing thin eggshells that break before the chicks hatch
High DDT levels disturb calcium metabolism in birds, so their eggshells become thin and break prematurely, reducing breeding success. This caused sharp declines in fish-eating birds and birds of prey.
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Q.109
Third-generation biofuels are produced from
- A Sugarcane and corn
- B Jatropha and other non-edible oilseeds
- C Algae
- D Genetically engineered crops
Show answer
Correct answer: (C) Algae
First-generation biofuels come from food crops, second-generation from non-food biomass such as jatropha and crop residue, third-generation from algae, and fourth-generation from genetically engineered organisms.
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Q.110
Which of the following is NOT an effect of acid rain?
- A Leaching of nutrients from the soil
- B Corrosion of buildings and monuments
- C Harm to fish and other life in lakes
- D Thickening of the ozone layer
Show answer
Correct answer: (D) Thickening of the ozone layer
Acid rain washes nutrients such as calcium and magnesium out of soil, corrodes stone and metal, and makes lakes too acidic for fish. It plays no part in thickening the ozone layer.
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Q.111
The 'Keeling Curve', the continuous record of rising atmospheric carbon dioxide begun in 1958, is based on measurements taken at
- A Mauna Loa, Hawaii
- B Hanle, Ladakh
- C Cape Grim, Tasmania
- D Svalbard, Norway
Show answer
Correct answer: (A) Mauna Loa, Hawaii
Charles David Keeling began precise CO2 measurements at the Mauna Loa Observatory in Hawaii in 1958. The curve shows a steady rise with a small yearly zig-zag caused by the seasonal growth of plants in the Northern Hemisphere.
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Q.112
In the IUCN Red List, which of the following categories indicates the highest risk of extinction in the wild?
- A Vulnerable
- B Endangered
- C Critically Endangered
- D Near Threatened
Show answer
Correct answer: (C) Critically Endangered
The threatened categories in rising order of risk are Vulnerable, Endangered and Critically Endangered; beyond that come Extinct in the Wild and Extinct. Near Threatened is below Vulnerable.
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Q.113
The Vikramshila Gangetic Dolphin Sanctuary, a protected stretch of the Ganga for the river dolphin, is located in
- A Bihar
- B Uttar Pradesh
- C West Bengal
- D Assam
Show answer
Correct answer: (A) Bihar
The sanctuary covers the Ganga between Sultanganj and Kahalgaon in Bhagalpur district of Bihar and protects the Gangetic dolphin, India's national aquatic animal.
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Q.114
Which ecological pyramid can never be inverted in any ecosystem?
- A Pyramid of numbers
- B Pyramid of biomass
- C Pyramid of energy
- D All three can be inverted
Show answer
Correct answer: (C) Pyramid of energy
Energy decreases at every successive trophic level because of the 10 percent law, so the pyramid of energy is always upright. Pyramids of numbers and biomass can be inverted in some ecosystems.
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Q.115
Green plants, which manufacture their own food from simple inorganic substances using sunlight, occupy the first trophic level and are called
- A Heterotrophs
- B Saprotrophs
- C Detritivores
- D Autotrophs
Show answer
Correct answer: (D) Autotrophs
Green plants are autotrophs (producers): they make their own food by photosynthesis and form the first trophic level. Heterotrophs, including saprotrophs and detritivores, depend on food made by others.
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Q.116
Classical (London-type) smog, a mixture of smoke, fog and sulphur dioxide, is chemically ___ in nature, whereas photochemical smog is ___ in nature.
- A Oxidising; reducing
- B Neutral; basic
- C Basic; neutral
- D Reducing; oxidising
Show answer
Correct answer: (D) Reducing; oxidising
Classical smog forms in cool, humid weather from coal smoke and sulphur dioxide and is a reducing mixture, so it is also called reducing smog. Photochemical smog is rich in oxidising agents such as ozone and PAN, so it is called oxidising smog.
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Q.117
'Silent Spring' (1962), the book that drew worldwide attention to the harm caused by pesticides such as DDT, was written by
- A Jane Goodall
- B Wangari Maathai
- C Rachel Carson
- D Vandana Shiva
Show answer
Correct answer: (C) Rachel Carson
American biologist Rachel Carson's 'Silent Spring' showed how pesticides were killing birds and other wildlife and helped launch the modern environmental movement. Jane Goodall is known for her study of chimpanzees.
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Q.118
Under the Wildlife (Protection) Act 1972, animals listed in which Schedule receive the highest degree of protection?
- A Schedule I
- B Schedule II
- C Schedule III
- D Schedule IV
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Correct answer: (A) Schedule I
Schedule I species such as the tiger, elephant, lion and Great Indian Bustard get absolute protection, and offences against them carry the highest penalties. Protection decreases through the later schedules.
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Q.119
Plants such as mangroves that are adapted to grow in saline soil or salt water are called
- A Xerophytes
- B Hydrophytes
- C Epiphytes
- D Halophytes
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Correct answer: (D) Halophytes
Halophytes tolerate high salt levels; mangroves, for example, exclude or excrete salt. Xerophytes are adapted to dry conditions, hydrophytes to living in water, and epiphytes grow on other plants.
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Q.120
Under the Wildlife (Protection) Act, 1972, as amended, which of the following is NOT one of the categories of 'protected area'?
- A National park
- B Biosphere reserve
- C Conservation reserve
- D Community reserve
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Correct answer: (B) Biosphere reserve
The Act defines a protected area as a national park, a sanctuary, a conservation reserve or a community reserve. Biosphere reserves are designated through the national biosphere reserve programme and UNESCO's MAB framework, not under this Act.
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Q.121
The Montreux Record maintained under the Ramsar Convention is a register of
- A Wetlands where ecological change has occurred or is likely due to human interference
- B Newly declared wetlands of international importance
- C Wetlands that have been completely drained
- D Coral reefs under threat
Show answer
Correct answer: (A) Wetlands where ecological change has occurred or is likely due to human interference
The Montreux Record lists Ramsar sites whose ecological character is threatened by pollution or other human interference. Keoladeo (Rajasthan) and Loktak (Manipur) were placed on it; Chilika was removed in 2002.
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Q.122
Reef-building corals grow best in
- A Warm, clear, shallow sea water
- B Cold, deep ocean water
- C Muddy water near large river mouths
- D Freshwater lakes
Show answer
Correct answer: (A) Warm, clear, shallow sea water
Their symbiotic algae need sunlight, so reef corals need clear, shallow, warm salt water; sediment-laden water near large river mouths blocks light and smothers them.
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Q.123
The first biosphere reserve of India, established in 1986, is the
- A Nanda Devi Biosphere Reserve
- B Nilgiri Biosphere Reserve
- C Sundarbans Biosphere Reserve
- D Gulf of Mannar Biosphere Reserve
Show answer
Correct answer: (B) Nilgiri Biosphere Reserve
The Nilgiri Biosphere Reserve, spread over Tamil Nadu, Kerala and Karnataka, was India's first biosphere reserve (1986) and the first Indian one included in UNESCO's World Network of Biosphere Reserves.
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Q.124
Lichens are widely used as biological indicators of air pollution because they do not grow well in air polluted by
- A Sulphur dioxide
- B Carbon dioxide
- C Nitrogen
- D Water vapour
Show answer
Correct answer: (A) Sulphur dioxide
Lichens are very sensitive to sulphur dioxide, so their absence or poor growth near cities and industries signals SO2 pollution. Carbon dioxide, nitrogen and water vapour are normal parts of air that lichens tolerate.
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Q.125
The National Chambal Sanctuary, spread over Rajasthan, Madhya Pradesh and Uttar Pradesh, is mainly known for the conservation of the
- A Hangul
- B Olive Ridley turtle
- C Gharial
- D Nilgiri tahr
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Correct answer: (C) Gharial
This tri-state river sanctuary is a key stronghold of the fish-eating gharial; it also protects the Gangetic dolphin, the mugger and several freshwater turtles.
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Q.126
Ocean acidification, which threatens corals and shell-forming marine animals, is caused mainly by
- A Absorption of atmospheric carbon dioxide by seawater
- B Dumping of sulphuric acid by ships
- C Melting of sea ice
- D Salt carried into the sea by rivers
Show answer
Correct answer: (A) Absorption of atmospheric carbon dioxide by seawater
Seawater absorbs a large part of the carbon dioxide emitted by humans and forms carbonic acid, which lowers the pH and reduces the carbonate that corals and molluscs need to build their skeletons and shells.
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Q.127
The concept of 'biodiversity hotspots' was given in 1988 by
- A Norman Myers
- B E.O. Wilson
- C Rachel Carson
- D Walter Rosen
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Correct answer: (A) Norman Myers
British ecologist Norman Myers identified biodiversity hotspots as regions rich in endemic species but under severe threat. Walter Rosen coined the word 'biodiversity' and E.O. Wilson popularised it.
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Q.128
Which of the following pairs of an environmental case and the principle it is best known for is correctly matched?
- A Oleum gas leak case (M.C. Mehta v. Union of India) - Absolute liability
- B Vellore Citizens' Welfare Forum case - Public trust doctrine
- C M.C. Mehta v. Kamal Nath - Absolute liability
- D Indian Council for Enviro-Legal Action case - Public trust doctrine
Show answer
Correct answer: (A) Oleum gas leak case (M.C. Mehta v. Union of India) - Absolute liability
After the oleum gas leak in Delhi, the Supreme Court laid down absolute liability for hazardous industries, stricter than strict liability because no exceptions are allowed. The Vellore case applied the precautionary and polluter pays principles, while Kamal Nath is known for the public trust doctrine.
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Q.129
The Minamata Convention (2013) on mercury is named after a city in
- A China
- B South Korea
- C Japan
- D Thailand
Show answer
Correct answer: (C) Japan
The convention to control mercury emissions and products is named after Minamata in Japan, where industrial mercury discharge caused the Minamata disease outbreak in the 1950s. It came into force in 2017.
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Q.130
A high Biochemical Oxygen Demand (BOD) value for a river indicates that the water
- A Is very clean
- B Has a high dissolved oxygen content
- C Is at a low temperature
- D Is heavily polluted with organic matter
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Correct answer: (D) Is heavily polluted with organic matter
BOD is the oxygen that microbes need to decompose the organic matter in water. More organic pollution means more oxygen is demanded, so a high BOD signals heavy pollution and low dissolved oxygen.
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Q.131
Dachigam National Park near Srinagar is the last major refuge of which endangered animal?
- A Hangul (Kashmir stag)
- B Nilgai
- C Barasingha
- D Chinkara
Show answer
Correct answer: (A) Hangul (Kashmir stag)
The hangul or Kashmir stag, the state animal of Jammu and Kashmir, survives mainly in Dachigam National Park. The barasingha (swamp deer) is associated with Kanha in Madhya Pradesh.
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Q.132
In the waste management hierarchy, which option is the most preferred?
- A Recycling
- B Landfilling
- C Incineration with energy recovery
- D Reducing waste at the source
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Correct answer: (D) Reducing waste at the source
The hierarchy ranks prevention or reduction at source highest, followed by reuse, recycling and energy recovery, with disposal in landfills as the least preferred option. Waste that is never produced needs no handling.
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Q.133
Which adaptation helps mangrove trees survive in waterlogged, oxygen-poor saline mud?
- A Thorny stems
- B Pneumatophores (breathing roots)
- C Succulent leaves
- D Deep tap roots
Show answer
Correct answer: (B) Pneumatophores (breathing roots)
Mangroves such as Avicennia send up pneumatophores, roots that grow vertically out of the mud to take in oxygen. Many mangroves also show viviparous germination, where seeds sprout on the parent tree.
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Q.134
The UN Conference on Environment and Development (Earth Summit), where the UNFCCC and the CBD were opened for signature, was held at Rio de Janeiro in
- A 1972
- B 1987
- C 1992
- D 1997
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Correct answer: (C) 1992
The 1992 Rio Earth Summit produced the UNFCCC, the Convention on Biological Diversity, Agenda 21 and the Rio Declaration. 1972 was the Stockholm Conference and 1997 the Kyoto Protocol.
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Q.135
Coral bleaching, in which corals expel their symbiotic algae and turn white, is mainly caused by
- A Decrease in salinity
- B Increase in dissolved oxygen
- C Reduced sunlight
- D Rise in sea surface temperature
Show answer
Correct answer: (D) Rise in sea surface temperature
Corals depend on symbiotic algae called zooxanthellae for colour and food. When sea water becomes unusually warm, the corals expel these algae and appear white; prolonged bleaching kills the reef.
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Q.136
Which of the following was NOT among the greenhouse gases listed in Annex A of the Kyoto Protocol (1997)?
- A Methane
- B Nitrous oxide
- C Chlorofluorocarbons
- D Perfluorocarbons
Show answer
Correct answer: (C) Chlorofluorocarbons
Kyoto covered six gases: carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulphur hexafluoride. CFCs were left out because they were already being phased out under the Montreal Protocol.
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Q.137
India is counted among the megadiverse countries of the world. Approximately what share of the world's land area does India occupy?
- A About 0.5 percent
- B About 2.4 percent
- C About 8 percent
- D About 12 percent
Show answer
Correct answer: (B) About 2.4 percent
India has only about 2.4 percent of the world's land area but about 8 percent of the world's recorded species, which is why it is counted among the megadiverse countries.
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Q.138
Which of the following is an abiotic component of an ecosystem?
- A Fungi
- B Earthworm
- C Sunlight
- D Bacteria
Show answer
Correct answer: (C) Sunlight
Abiotic components are the non-living physical and chemical factors such as sunlight, temperature, water, soil and minerals. Fungi, earthworms and bacteria are living (biotic) components.
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Q.139
The Jatayu Conservation Breeding Centre, set up to breed vultures in captivity after their population crash, is located at Pinjore in
- A Punjab
- B Himachal Pradesh
- C Uttarakhand
- D Haryana
Show answer
Correct answer: (D) Haryana
The centre at Pinjore in Panchkula district, Haryana, is run by the Haryana Forest Department with the Bombay Natural History Society and breeds white-backed, long-billed and slender-billed vultures.
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Q.140
Heavy use of nitrogen-based fertilisers in agriculture is a major source of which greenhouse gas?
- A Nitrous oxide
- B Carbon monoxide
- C Methane
- D Chlorofluorocarbons
Show answer
Correct answer: (A) Nitrous oxide
Soil bacteria convert part of the nitrogen in fertilisers into nitrous oxide, a long-lived and powerful greenhouse gas. Agriculture is the main human source of this gas.
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Q.141
The 'rivet popper' hypothesis, which compares the species of an ecosystem to the rivets of an aeroplane, was proposed by
- A Edward O. Wilson
- B David Tilman
- C Paul Ehrlich
- D Robert May
Show answer
Correct answer: (C) Paul Ehrlich
Paul Ehrlich argued that removing rivets (species) one by one may not harm the aeroplane (ecosystem) at first, but over time weakens it, and losing key rivets, like those on the wings, is especially dangerous.
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Q.142
Microplastics, now found in oceans, rivers, soil and even drinking water, are generally defined as plastic particles smaller than
- A 5 micrometres
- B 5 millimetres
- C 5 centimetres
- D 50 centimetres
Show answer
Correct answer: (B) 5 millimetres
Plastic pieces under 5 mm are called microplastics; they come from the breakdown of larger plastic items and from sources such as synthetic fibres and microbeads. Their small size lets them enter food chains.
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Q.143
Halons, bromine-containing ozone-depleting substances controlled under the Montreal Protocol, were widely used in
- A Chemical fertilisers
- B Fire extinguishers
- C Car batteries
- D Wall paints
Show answer
Correct answer: (B) Fire extinguishers
Halons were valued as fire-fighting agents, but the bromine they release destroys ozone even more effectively, atom for atom, than chlorine. Their production was therefore phased out under the Montreal Protocol.
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Q.144
Old cathode ray tube (CRT) televisions and computer monitors are hazardous e-waste mainly because their glass contains large amounts of
- A Lead
- B Calcium
- C Magnesium
- D Potassium
Show answer
Correct answer: (A) Lead
CRT glass contains lead to shield users from X-rays, and lead leaching from dumped CRTs can contaminate soil and water. Lead is a neurotoxin that particularly harms children.
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Q.145
Along with Chilika Lake in Odisha, which wetland was among the first two Indian sites designated under the Ramsar Convention in 1981?
- A Keoladeo National Park
- B Wular Lake
- C Loktak Lake
- D Sambhar Lake
Show answer
Correct answer: (A) Keoladeo National Park
Chilika Lake and Keoladeo National Park at Bharatpur, Rajasthan, were designated when India joined the Ramsar Convention in 1981. Wular, Loktak and Sambhar were added later, in 1990.
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Q.146
Which of the following is NOT one of the major coral reef areas of India?
- A Sundarbans
- B Gulf of Mannar
- C Lakshadweep
- D Andaman and Nicobar Islands
Show answer
Correct answer: (A) Sundarbans
India's main reef areas are the Gulf of Kutch, the Gulf of Mannar, Lakshadweep and the Andaman and Nicobar Islands. The Sundarbans delta has muddy, sediment-laden water of low salinity in which reef corals cannot grow.
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Q.147
The maximum population size of a species that an environment can support indefinitely with its available resources is called its
- A Carrying capacity
- B Biotic potential
- C Natality
- D Population density
Show answer
Correct answer: (A) Carrying capacity
Carrying capacity (K) is the upper limit set by food, space and other resources. Biotic potential is the maximum rate of increase under ideal conditions, and natality is the birth rate.
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Q.148
The use of green plants to remove, break down or lock up pollutants such as heavy metals in soil and water is called
- A Phytoremediation
- B Biomagnification
- C Eutrophication
- D Bioaccumulation
Show answer
Correct answer: (A) Phytoremediation
In phytoremediation, plants absorb or degrade contaminants; some species, for example, take up heavy metals into their tissues, which are then harvested. It is a form of bioremediation, which more broadly also uses microbes.
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Q.149
Green plants capture only a small fraction of the photosynthetically active radiation (PAR) that falls on them. This fraction is about
- A 2 to 10 percent
- B 20 to 30 percent
- C 40 to 50 percent
- D 70 to 80 percent
Show answer
Correct answer: (A) 2 to 10 percent
Less than half of incident sunlight is PAR, and plants capture only about 2 to 10 percent of it; this small amount of energy sustains almost the entire living world.
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Q.150
Under the Biological Diversity Act 2002, People's Biodiversity Registers documenting local plants, animals and traditional knowledge are prepared by the
- A National Biodiversity Authority
- B State Biodiversity Boards
- C Biodiversity Management Committees
- D Central Pollution Control Board
Show answer
Correct answer: (C) Biodiversity Management Committees
The Act has a three-tier structure: the National Biodiversity Authority, State Biodiversity Boards and Biodiversity Management Committees at the level of local bodies. The BMCs prepare People's Biodiversity Registers with the help of local people, a duty set out in the Biological Diversity Rules 2004; the 2023 amendment of the Act kept this three-tier structure and the BMCs' role.
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How these questions were made
Authored by an AI assistant (Claude) from its own general knowledge of stable, well-established facts (no live lookup) - not reviewed by a subject-matter expert; verify against an official source before relying on any fact.