{"id":13030,"date":"2025-09-26T08:13:45","date_gmt":"2025-09-26T07:13:45","guid":{"rendered":"https:\/\/mcqsadda.com\/?p=13030"},"modified":"2025-10-22T11:43:15","modified_gmt":"2025-10-22T10:43:15","slug":"ecology-top-100-mcqs-with-answer-and-explanation","status":"publish","type":"post","link":"https:\/\/mcqsadda.com\/index.php\/2025\/09\/26\/ecology-top-100-mcqs-with-answer-and-explanation\/","title":{"rendered":"Ecology Top 100 MCQs With Answer and Explanation"},"content":{"rendered":"\n

1. The scientific study of the relationship between organisms and their environment is called:
<\/mark><\/strong>A) Biology
B) Ecology
C) Geology
D) Sociology
Answer:<\/strong> B) Ecology
Explanation:<\/strong> Ecology is derived from the Greek word Oikos<\/em> (house) and Logos<\/em> (study). It deals with interactions of living organisms with each other and their environment.<\/p>\n\n\n\n

2. Who is regarded as the “Father of Ecology”?
<\/mark><\/strong>A) Charles Darwin
B) Haeckel
C) Odum
D) Wallace
Answer:<\/strong> B) Haeckel
Explanation:<\/strong> Ernst Haeckel coined the term \u201cEcology\u201d in 1869.<\/p>\n\n\n\n

3. Which of the following is a biotic component of an ecosystem?
<\/mark><\/strong>A) Temperature
B) Rainfall
C) Plants
D) Soil
Answer:<\/strong> C) Plants
Explanation:<\/strong> Biotic components include living things such as plants, animals, and microorganisms.<\/p>\n\n\n\n

4. Which of the following is an abiotic factor?
<\/mark><\/strong>A) Birds
B) Fungi
C) Minerals
D) Bacteria
Answer:<\/strong> C) Minerals
Explanation:<\/strong> Abiotic factors are non-living components such as soil, water, temperature, and minerals.<\/p>\n\n\n\n

5. The largest ecosystem on Earth is:
<\/mark><\/strong>A) Desert
B) Grassland
C) Ocean
D) Forest
Answer:<\/strong> C) Ocean
Explanation:<\/strong> Oceans cover ~71% of Earth\u2019s surface and form the largest ecosystem.<\/p>\n\n\n\n

6. A group of similar organisms capable of interbreeding and producing fertile offspring is called:
<\/mark><\/strong>A) Population
B) Species
C) Community
D) Genus
Answer:<\/strong> B) Species
Explanation:<\/strong> Species is the basic unit of classification and biodiversity.<\/p>\n\n\n\n

7. The functional unit of ecology is:
<\/mark><\/strong>A) Population
B) Ecosystem
C) Community
D) Habitat
Answer:<\/strong> B) Ecosystem
Explanation:<\/strong> Ecosystem includes both biotic and abiotic components interacting as a system.<\/p>\n\n\n\n

8. The pyramid of energy in any ecosystem is always:
<\/mark><\/strong>A) Upright
B) Inverted
C) Cylindrical
D) Variable
Answer:<\/strong> A) Upright
Explanation:<\/strong> Energy flow decreases at each trophic level, hence pyramid of energy is always upright.<\/p>\n\n\n\n

9. The transfer of energy from one trophic level to the next is approximately:
<\/mark><\/strong>A) 5%
B) 10%
C) 20%
D) 50%
Answer:<\/strong> B) 10%
Explanation:<\/strong> According to Lindeman\u2019s 10% law, only about 10% of energy is transferred to the next trophic level.<\/p>\n\n\n\n

10. Which ecosystem has the highest productivity?
<\/mark><\/strong>A) Desert
B) Ocean
C) Tropical Rainforest
D) Grassland
Answer:<\/strong> C) Tropical Rainforest
Explanation:<\/strong> Tropical rainforests have high temperature, moisture, and biodiversity, resulting in maximum productivity.<\/p>\n\n\n\n

11. The branch of ecology that deals with individual species is:
<\/mark><\/strong>A) Synecology
B) Autecology
C) Paleontology
D) Phylogeny
Answer:<\/strong> B) Autecology
Explanation:<\/strong> Autecology studies the ecology of a single species, while synecology studies groups of species.<\/p>\n\n\n\n

12. Which of the following is an example of a primary consumer?
<\/mark><\/strong>A) Lion
B) Goat
C) Hawk
D) Tiger
Answer:<\/strong> B) Goat
Explanation:<\/strong> Goats feed on plants (producers), hence are herbivores and primary consumers.<\/p>\n\n\n\n

13. Secondary consumers are generally:
<\/mark><\/strong>A) Herbivores
B) Carnivores
C) Decomposers
D) Producers
Answer:<\/strong> B) Carnivores
Explanation:<\/strong> Secondary consumers feed on herbivores.<\/p>\n\n\n\n

14. The organisms that break down dead organic matter are called:
<\/mark><\/strong>A) Consumers
B) Decomposers
C) Producers
D) Predators
Answer:<\/strong> B) Decomposers
Explanation:<\/strong> Decomposers (fungi, bacteria) recycle nutrients by decomposing dead matter.<\/p>\n\n\n\n

15. Energy flow in an ecosystem is:
<\/mark><\/strong>A) Cyclic
B) Linear and unidirectional
C) Multidirectional
D) Static
Answer:<\/strong> B) Linear and unidirectional
Explanation:<\/strong> Energy flows from sun \u2192 producers \u2192 consumers \u2192 decomposers, and is not recycled.<\/p>\n\n\n\n

16. The self-sufficient ecosystem is:
<\/mark><\/strong>A) Pond
B) Desert
C) Grassland
D) Ocean
Answer:<\/strong> A) Pond
Explanation:<\/strong> A pond contains producers, consumers, decomposers, and abiotic components \u2013 making it self-sufficient.<\/p>\n\n\n\n

17. Which of the following is NOT a renewable resource?
<\/mark><\/strong>A) Solar energy
B) Wind energy
C) Fossil fuels
D) Water
Answer:<\/strong> C) Fossil fuels
Explanation:<\/strong> Fossil fuels take millions of years to form, hence are non-renewable.<\/p>\n\n\n\n

18. The concept of \u201cEcological Niche\u201d was introduced by:
<\/mark><\/strong>A) Grinnell
B) Haeckel
C) Odum
D) Darwin
Answer:<\/strong> A) Grinnell
Explanation:<\/strong> Joseph Grinnell introduced the ecological niche concept in 1917.<\/p>\n\n\n\n

19. The sum of all ecosystems on Earth is called:
<\/mark><\/strong>A) Lithosphere
B) Biosphere
C) Atmosphere
D) Hydrosphere
Answer:<\/strong> B) Biosphere
Explanation:<\/strong> Biosphere includes all life forms and ecosystems of Earth.<\/p>\n\n\n\n

20. Which cycle does not have an atmospheric component?
<\/mark><\/strong>A) Carbon cycle
B) Nitrogen cycle
C) Phosphorus cycle
D) Oxygen cycle
Answer:<\/strong> C) Phosphorus cycle
Explanation:<\/strong> Phosphorus cycle lacks a gaseous phase, it occurs mainly in rocks and soil.<\/p>\n\n\n\n

21. The natural place of an organism is called its:
<\/mark><\/strong>A) Habitat
B) Niche
C) Territory
D) Domain
Answer:<\/strong> A) Habitat
Explanation:<\/strong> Habitat is the physical environment where an organism lives.<\/p>\n\n\n\n

22. The process of self-purification of water bodies by natural means is called:
<\/mark><\/strong>A) Eutrophication
B) Bioremediation
C) Self-regulation
D) Natural attenuation
Answer:<\/strong> D) Natural attenuation
Explanation:<\/strong> It refers to the natural capacity of ecosystems to purify themselves.<\/p>\n\n\n\n

23. Which is the major reservoir of carbon?
<\/mark><\/strong>A) Plants
B) Atmosphere
C) Oceans
D) Soil
Answer:<\/strong> C) Oceans
Explanation:<\/strong> Oceans store the largest amount of carbon in dissolved form.<\/p>\n\n\n\n

24. Which ecological pyramid can be inverted?
<\/strong><\/mark>A) Pyramid of energy
B) Pyramid of number
C) Pyramid of biomass
D) Both B & C
Answer:<\/strong> D) Both B & C
Explanation:<\/strong> Pyramids of number and biomass can be inverted (e.g., tree ecosystem, aquatic system), but energy pyramid is always upright.<\/p>\n\n\n\n

25. Which type of succession starts on bare rocks?
<\/mark><\/strong>A) Primary succession
B) Secondary succession
C) Hydrarch succession
D) Xerarch succession
Answer:<\/strong> A) Primary succession
Explanation:<\/strong> Primary succession begins on previously uninhabited surfaces like rocks, sand, or lava.<\/p>\n\n\n\n

26. A group of individuals of the same species living in a particular area is called:
<\/mark><\/strong>A) Community
B) Population
C) Ecosystem
D) Biome
Answer:<\/strong> B) Population
Explanation:<\/strong> Population refers to all individuals of one species in a given area at a given time.<\/p>\n\n\n\n

27. The maximum number of individuals of a species that an environment can support is called:
<\/mark><\/strong>A) Population density
B) Carrying capacity
C) Growth potential
D) Natality
Answer:<\/strong> B) Carrying capacity
Explanation:<\/strong> Carrying capacity is the sustainable limit of population supported by resources.<\/p>\n\n\n\n

28. The J-shaped population growth curve represents:
<\/mark><\/strong>A) Logistic growth
B) Exponential growth
C) Declining growth
D) Stable growth
Answer:<\/strong> B) Exponential growth
Explanation:<\/strong> Exponential growth shows rapid increase without environmental resistance, forming a J-curve.<\/p>\n\n\n\n

29. In logistic growth, the population growth curve is:
<\/mark><\/strong>A) J-shaped
B) S-shaped
C) Linear
D) Bell-shaped
Answer:<\/strong> B) S-shaped
Explanation:<\/strong> Logistic growth includes environmental resistance and stabilizes at carrying capacity, forming an S-curve.<\/p>\n\n\n\n

30. Population density refers to:
<\/mark><\/strong>A) Number of species in a biome
B) Number of organisms per unit area
C) Growth rate of organisms
D) Reproductive capacity
Answer:<\/strong> B) Number of organisms per unit area
Explanation:<\/strong> Population density = Population size \u00f7 Area.<\/p>\n\n\n\n

31. The interaction in which both species benefit is called:
<\/mark><\/strong>A) Parasitism
B) Commensalism
C) Mutualism
D) Predation
Answer:<\/strong> C) Mutualism
Explanation:<\/strong> In mutualism, both organisms gain (e.g., bees and flowers).<\/p>\n\n\n\n

32. The ecological interaction in which one species is harmed and the other is unaffected is:
<\/mark><\/strong>A) Commensalism
B) Amensalism
C) Mutualism
D) Competition
Answer:<\/strong> B) Amensalism
Explanation:<\/strong> Example \u2013 Penicillium secretes penicillin that kills bacteria, but Penicillium is unaffected.<\/p>\n\n\n\n

33. Which biome is characterized by permafrost?
<\/mark><\/strong>A) Desert
B) Grassland
C) Tundra
D) Rainforest
Answer:<\/strong> C) Tundra
Explanation:<\/strong> Tundra biome has permanently frozen subsoil (permafrost).<\/p>\n\n\n\n

34. Which of the following is the largest terrestrial biome?
<\/mark><\/strong>A) Tropical rainforest
B) Taiga (boreal forest)
C) Desert
D) Grassland
Answer:<\/strong> B) Taiga (boreal forest)
Explanation:<\/strong> The boreal forest covers Canada, Russia, and Northern Europe, making it the largest land biome.<\/p>\n\n\n\n

35. Which biome has the greatest biodiversity?
<\/mark><\/strong>A) Desert
B) Grassland
C) Temperate forest
D) Tropical rainforest
Answer:<\/strong> D) Tropical rainforest
Explanation:<\/strong> Tropical rainforests near the equator have maximum biodiversity due to warm, moist conditions.<\/p>\n\n\n\n

36. The desert biome is characterized by:
<\/mark><\/strong>A) High rainfall, low temperature
B) Low rainfall, high evaporation
C) High biodiversity and rainfall
D) Rich soils and grasses
Answer:<\/strong> B) Low rainfall, high evaporation
Explanation:<\/strong> Deserts receive <25 cm of rainfall annually and have high evaporation rates.<\/p>\n\n\n\n

37. Which biome is dominated by grasses and grazing animals?
<\/mark><\/strong>A) Tundra
B) Grassland
C) Desert
D) Rainforest
Answer:<\/strong> B) Grassland
Explanation:<\/strong> Grasslands support grasses, herbivores, and large grazers (e.g., bison, antelopes).<\/p>\n\n\n\n

38. The gradual replacement of one community by another in an ecosystem is called:
<\/mark><\/strong>A) Adaptation
B) Ecological succession
C) Evolution
D) Colonization
Answer:<\/strong> B) Ecological succession
Explanation:<\/strong> Succession is the sequential development of communities in an area.<\/p>\n\n\n\n

39. The first species to colonize bare areas in primary succession are called:
<\/mark><\/strong>A) Dominant species
B) Pioneer species
C) Climax species
D) Invasive species
Answer:<\/strong> B) Pioneer species
Explanation:<\/strong> Pioneer species (lichens, mosses) modify the environment, making it suitable for other species.<\/p>\n\n\n\n

40. Primary succession takes place on:
<\/mark><\/strong>A) Bare rocks
B) Abandoned farmland
C) Burned forests
D) Flooded landsAnswer:<\/strong> A) Bare rocks
Explanation:<\/strong> Primary succession begins in lifeless areas with no soil (rocks, lava, sand dunes).<\/p>\n\n\n\n

41. Secondary succession occurs on:
<\/mark><\/strong>A) Newly formed land
B) Bare rock
C) Disturbed areas with soil
D) Oceans
Answer:<\/strong> C) Disturbed areas with soil
Explanation:<\/strong> Secondary succession happens after disturbances like fire, flood, or human activity but soil remains.<\/p>\n\n\n\n

42. The final stable community formed after succession is called:
<\/mark><\/strong>A) Climax community
B) Pioneer community
C) Transitional community
D) Secondary community
Answer:<\/strong> A) Climax community
Explanation:<\/strong> The climax community is stable, self-sustaining, and in equilibrium with the environment.<\/p>\n\n\n\n

43. Xerarch succession begins in:
<\/mark><\/strong>A) Water bodies
B) Dry habitats
C) Swamps
D) Oceans
Answer:<\/strong> B) Dry habitats
Explanation:<\/strong> Xerarch succession starts in dry areas such as rocks and sand.<\/p>\n\n\n\n

44. Hydrarch succession begins in:
<\/mark><\/strong>A) Desert
B) Lakes or ponds
C) Forests
D) Grassland
Answer:<\/strong> B) Lakes or ponds
Explanation:<\/strong> Hydrarch succession starts in aquatic habitats and leads to terrestrial vegetation.<\/p>\n\n\n\n

45. Which species play a crucial role in maintaining ecosystem structure and functioning?
<\/mark><\/strong>A) Endangered species
B) Pioneer species
C) Keystone species
D) Exotic species
Answer:<\/strong> C) Keystone species
Explanation:<\/strong> Keystone species (e.g., tiger, sea otter) regulate ecosystem balance by controlling prey\/predator populations.<\/p>\n\n\n\n

46. Which biome is called \u201cthe lungs of the Earth\u201d?
<\/mark><\/strong>A) Savanna
B) Tropical rainforest
C) Tundra
D) Desert
Answer:<\/strong> B) Tropical rainforest
Explanation:<\/strong> Amazon rainforest produces ~20% of the Earth\u2019s oxygen, hence called \u201clungs of Earth.\u201d<\/p>\n\n\n\n

47. The process by which fertile land becomes desert due to overgrazing, deforestation, or climate change is:
<\/mark><\/strong>A) Succession
B) Desertification
C) Erosion
D) Salinization
Answer:<\/strong> B) Desertification
Explanation:<\/strong> Desertification is land degradation in arid regions, often caused by human activities.<\/p>\n\n\n\n

48. Biomes are primarily classified based on:
<\/mark><\/strong>A) Latitude
B) Vegetation and climate
C) Animal distribution
D) Soil type
Answer:<\/strong> B) Vegetation and climate
Explanation:<\/strong> Biomes are determined mainly by rainfall and temperature, which influence vegetation.<\/p>\n\n\n\n

49. Which of the following is an example of commensalism?
<\/mark><\/strong>A) Cattle egret and grazing cattle
B) Lion and zebra
C) Mosquito and human
D) Algae and fungi in lichen
Answer:<\/strong> A) Cattle egret and grazing cattle
Explanation:<\/strong> Egrets eat insects disturbed by cattle. Cattle is unaffected, egret benefits.<\/p>\n\n\n\n

50. The process by which a lake becomes nutrient-rich and supports excessive plant growth is called:
<\/mark><\/strong>A) Biomagnification
B) Eutrophication
C) Succession
D) Pollution
Answer:<\/strong> B) Eutrophication
Explanation:<\/strong> Eutrophication occurs when nutrient enrichment (N, P) causes algal blooms and oxygen depletion.<\/p>\n\n\n\n

51. The total variety of organisms in a given area is called:
<\/mark><\/strong>A) Ecology
B) Biodiversity
C) Biogeography
D) Endemism
Answer:<\/strong> B) Biodiversity
Explanation:<\/strong> Biodiversity includes genetic diversity, species diversity, and ecosystem diversity.<\/p>\n\n\n\n

52. Which country has the highest biodiversity in the world?
<\/mark><\/strong>A) Brazil
B) India
C) USA
D) China
Answer:<\/strong> A) Brazil
Explanation:<\/strong> Brazil, home to the Amazon rainforest, is the most biodiverse country.<\/p>\n\n\n\n

53. India is one of the world\u2019s:
<\/mark><\/strong>A) 5 megadiverse countries
B) 12 megadiverse countries
C) 17 megadiverse countries
D) 25 megadiverse countries
Answer:<\/strong> C) 17 megadiverse countries
Explanation:<\/strong> India is among 17 megadiverse nations that harbor majority of Earth\u2019s species.<\/p>\n\n\n\n

54. Which of the following is a biodiversity hotspot in India?
<\/mark><\/strong>A) Indo-Gangetic plains
B) Himalaya
C) Thar Desert
D) Sundarbans
Answer:<\/strong> B) Himalaya
Explanation:<\/strong> India has 4 biodiversity hotspots: Himalaya, Indo-Burma, Indo-Malayan, and Western Ghats.<\/p>\n\n\n\n

55. Endemic species are:<\/strong>
<\/mark>A) Found everywhere
B) Found only in a particular region
C) Alien species
D) Migratory species
Answer:<\/strong> B) Found only in a particular region
Explanation:<\/strong> Endemic species occur naturally in a single geographic location (e.g., Nilgiri Tahr in Western Ghats).<\/p>\n\n\n\n

56. Which of the following is a critically endangered species in India?
<\/mark><\/strong>A) Tiger
B) Lion-tailed macaque
C) Great Indian bustard
D) Peacock
Answer:<\/strong> C) Great Indian bustard
Explanation:<\/strong> The Great Indian bustard is one of the most critically endangered birds in India.<\/p>\n\n\n\n

57. The Red Data Book contains information about:
<\/mark><\/strong>A) Medicinal plants
B) Endangered species
C) Alien species
D) Domesticated animals
Answer:<\/strong> B) Endangered species
Explanation:<\/strong> The IUCN Red Data Book lists threatened and endangered species globally.<\/p>\n\n\n\n

58. Which organization publishes the Red List of Threatened Species?
<\/mark><\/strong>A) WWF
B) IUCN
C) UNEP
D) UNDP
Answer:<\/strong> B) IUCN
Explanation:<\/strong> The International Union for Conservation of Nature (IUCN) publishes the Red List.<\/p>\n\n\n\n

59. The term “biodiversity hotspot” was coined by:
<\/mark><\/strong>A) E.O. Wilson
B) Norman Myers
C) Charles Darwin
D) Haeckel
Answer:<\/strong> B) Norman Myers
Explanation:<\/strong> Norman Myers introduced the concept of biodiversity hotspots in 1988.<\/p>\n\n\n\n

60. In-situ conservation refers to:
<\/mark><\/strong>A) Protecting species outside their habitat
B) Protecting species within their natural habitat
C) Using biotechnology for conservation
D) Breeding animals in captivity
Answer:<\/strong> B) Protecting species within their natural habitat
Explanation:<\/strong> In-situ methods include national parks, wildlife sanctuaries, and biosphere reserves.<\/p>\n\n\n\n

61. Which of the following is an ex-situ conservation method?
<\/mark><\/strong>A) National parks
B) Wildlife sanctuaries
C) Botanical gardens
D) Biosphere reserves
Answer:<\/strong> C) Botanical gardens
Explanation:<\/strong> Ex-situ conservation includes zoos, botanical gardens, gene banks, and seed banks.<\/p>\n\n\n\n

62. The world\u2019s first national park was:
<\/mark><\/strong>A) Yellowstone (USA)
B) Jim Corbett (India)
C) Gir National Park (India)
D) Kruger (South Africa)
Answer:<\/strong> A) Yellowstone (USA)
Explanation:<\/strong> Yellowstone National Park was established in 1872 in the USA.<\/p>\n\n\n\n

63. The first national park in India was:
<\/mark><\/strong>A) Gir National Park
B) Kaziranga National Park
C) Jim Corbett National Park
D) Bandhavgarh National Park
Answer:<\/strong> C) Jim Corbett National Park
Explanation:<\/strong> Jim Corbett (then Hailey National Park) was established in 1936.<\/p>\n\n\n\n

64. Which biosphere reserve in India is included in UNESCO\u2019s World Network of Biosphere Reserves?
<\/mark><\/strong>A) Nanda Devi
B) Sundarbans
C) Nilgiri
D) All of these
Answer:<\/strong> D) All of these
Explanation:<\/strong> Several Indian biosphere reserves (e.g., Nilgiri, Sundarbans, Nanda Devi) are UNESCO recognized.<\/p>\n\n\n\n

65. Project Tiger was launched in India in:
<\/mark><\/strong>A) 1969
B) 1973
C) 1985
D) 1992
Answer:<\/strong> B) 1973
Explanation:<\/strong> Project Tiger was started in 1973 to conserve the endangered Bengal tiger.<\/p>\n\n\n\n

66. The Chipko Movement was primarily aimed at:
<\/mark><\/strong>A) Wildlife conservation
B) Forest conservation
C) Water conservation
D) Soil conservation
Answer:<\/strong> B) Forest conservation
Explanation:<\/strong> Chipko movement (1970s, Uttarakhand) involved hugging trees to prevent deforestation.<\/p>\n\n\n\n

67. Which gas is mainly responsible for ozone layer depletion?
<\/mark><\/strong>A) CO\u2082
B) CH\u2084
C) CFCs
D) SO\u2082
Answer:<\/strong> C) CFCs
Explanation:<\/strong> Chlorofluorocarbons (CFCs) break down ozone molecules, causing ozone holes.<\/p>\n\n\n\n

68. The Kyoto Protocol is related to:
<\/mark><\/strong>A) Biodiversity conservation
B) Wetland conservation
C) Climate change & greenhouse gas reduction
D) Ozone depletion
Answer:<\/strong> C) Climate change & greenhouse gas reduction
Explanation:<\/strong> Kyoto Protocol (1997) binds nations to reduce GHG emissions.<\/p>\n\n\n\n

69. The Montreal Protocol (1987) aims to control:
<\/mark><\/strong>A) Acid rain
B) Desertification
C) Ozone-depleting substances
D) Nuclear waste
Answer:<\/strong> C) Ozone-depleting substances
Explanation:<\/strong> Montreal Protocol regulates production of CFCs and other ozone-depleting chemicals.<\/p>\n\n\n\n

70. Which cycle does not involve a gaseous phase?
<\/mark><\/strong>A) Nitrogen cycle
B) Carbon cycle
C) Phosphorus cycle
D) Oxygen cycle
Answer:<\/strong> C) Phosphorus cycle
Explanation:<\/strong> Phosphorus cycle lacks a gaseous phase; it occurs in soil, rocks, and sediments.<\/p>\n\n\n\n

71. Nitrogen fixation is carried out by:
<\/mark><\/strong>A) Fungi
B) Algae
C) Bacteria
D) Viruses
Answer:<\/strong> C) Bacteria
Explanation:<\/strong> Nitrogen-fixing bacteria (Rhizobium, Azotobacter, Cyanobacteria) convert atmospheric N\u2082 into usable form.<\/p>\n\n\n\n

72. The process of conversion of ammonia into nitrates by bacteria is called:
<\/mark><\/strong>A) Nitrogen fixation
B) Ammonification
C) Nitrification
D) Denitrification
Answer:<\/strong> C) Nitrification
Explanation:<\/strong> Nitrifying bacteria (Nitrosomonas, Nitrobacter) convert ammonia into nitrites and nitrates.<\/p>\n\n\n\n

73. The process by which nitrates are reduced to gaseous nitrogen is:
<\/mark><\/strong>A) Denitrification
B) Nitrification
C) Assimilation
D) Ammonification
Answer:<\/strong> A) Denitrification
Explanation:<\/strong> Denitrifying bacteria (Pseudomonas) convert nitrates into N\u2082 gas.<\/p>\n\n\n\n

74. Which gas contributes the most to the greenhouse effect?
<\/mark><\/strong>A) CO\u2082
B) CH\u2084
C) CFCs
D) N\u2082O
Answer:<\/strong> A) CO\u2082
Explanation:<\/strong> Carbon dioxide is the main greenhouse gas responsible for global warming.<\/p>\n\n\n\n

75. The process of recycling nutrients in an ecosystem is mainly carried out by:
<\/mark><\/strong>A) Producers
B) Consumers
C) Decomposers
D) Herbivores
Answer:<\/strong> C) Decomposers
Explanation:<\/strong> Decomposers (bacteria, fungi) recycle nutrients by breaking down dead matter into usable forms.<\/p>\n\n\n\n

76. The species that invade a new habitat and spread rapidly, often displacing native species, are called:
<\/mark><\/strong>A) Endemic species
B) Exotic invasive species
C) Keystone species
D) Indicator species
Answer:<\/strong> B) Exotic invasive species
Explanation:<\/strong> Examples include Lantana camara<\/em>, Parthenium<\/em> (Congress grass), and Eichhornia<\/em> (water hyacinth).<\/p>\n\n\n\n

77. Biomagnification refers to:
<\/mark><\/strong>A) Increase in population size
B) Increase in energy flow in food chains
C) Increase in concentration of toxic substances at higher trophic levels
D) Increase in genetic diversity
Answer:<\/strong> C) Increase in concentration of toxic substances at higher trophic levels
Explanation:<\/strong> Persistent pollutants like DDT and mercury accumulate progressively up the food chain.<\/p>\n\n\n\n

78. Which of the following is a bio-indicator of air pollution?
<\/mark><\/strong>A) Lichens
B) Bats
C) Frogs
D) Grass
Answer:<\/strong> A) Lichens
Explanation:<\/strong> Lichens are sensitive to SO\u2082 and other pollutants, indicating air quality.<\/p>\n\n\n\n

79. The phenomenon of algae growth due to nutrient enrichment of water is called:
<\/mark><\/strong>A) Biomagnification
B) Eutrophication
C) Denitrification
D) Bioremediation
Answer:<\/strong> B) Eutrophication
Explanation:<\/strong> Excess nitrogen and phosphorus cause algal blooms, leading to oxygen depletion.<\/p>\n\n\n\n

80. Ramsar Convention (1971) is related to conservation of:
<\/mark><\/strong>A) Forests
B) Wetlands
C) Oceans
D) Deserts<\/p>\n\n\n\n

Answer:<\/strong> B) Wetlands
Explanation:<\/strong> Ramsar Convention provides a framework for the conservation of wetlands of international importance.<\/p>\n\n\n\n

81. Which is the largest Ramsar site in India (as of 2023)?
<\/mark><\/strong>A) Chilika Lake
B) Sundarbans
C) Ranganathittu
D) Sunderban Wetland
Answer:<\/strong> B) Sundarbans
Explanation:<\/strong> The Sundarban Wetland in West Bengal is India\u2019s largest Ramsar site.<\/p>\n\n\n\n

82. The major cause of biodiversity loss is:
<\/mark><\/strong>A) Overexploitation
B) Habitat destruction
C) Invasive species
D) Pollution
Answer:<\/strong> B) Habitat destruction
Explanation:<\/strong> Habitat destruction (deforestation, land-use change) is the leading cause of species extinction.<\/p>\n\n\n\n

83. The concept of \u201cEcological Footprint\u201d measures:
<\/mark><\/strong>A) Carbon emissions
B) Human demand on Earth\u2019s ecosystems
C) Ozone depletion rate
D) Water pollution levels
Answer:<\/strong> B) Human demand on Earth\u2019s ecosystems
Explanation:<\/strong> Ecological footprint indicates how much land\/water is needed to sustain human consumption.<\/p>\n\n\n\n

84. Which one of the following is NOT a greenhouse gas?
<\/mark><\/strong>A) CO\u2082
B) CH\u2084
C) O\u2082
D) N\u2082O
Answer:<\/strong> C) O\u2082
Explanation:<\/strong> Oxygen is not a greenhouse gas; it does not trap heat in the atmosphere.<\/p>\n\n\n\n

85. The maximum sustainable yield of a renewable resource refers to:
<\/mark><\/strong>A) Harvesting all available stock
B) Harvesting without allowing renewal
C) Harvesting at a rate that allows resource regeneration
D) Harvesting at random rates
Answer:<\/strong> C) Harvesting at a rate that allows resource regeneration
Explanation:<\/strong> MSY ensures long-term sustainability of renewable resources like fish and forests.<\/p>\n\n\n\n

86. Bioremediation refers to:
<\/mark><\/strong>A) Using chemicals to treat pollutants
B) Using organisms to clean polluted sites
C) Removing forests for cultivation
D) Recycling solid waste
Answer:<\/strong> B) Using organisms to clean polluted sites
Explanation:<\/strong> Example \u2013 Pseudomonas<\/em> bacteria used in oil spill cleanup.<\/p>\n\n\n\n

87. Which of the following is a secondary pollutant?
<\/mark><\/strong>A) SO\u2082
B) CO\u2082
C) O\u2083
D) NO\u2082
Answer:<\/strong> C) O\u2083
Explanation:<\/strong> Ground-level ozone is a secondary pollutant formed by reactions of NOx and hydrocarbons.<\/p>\n\n\n\n

88. The zone of atmosphere most important for weather phenomena is:
<\/mark><\/strong>A) Stratosphere
B) Troposphere
C) Mesosphere
D) Thermosphere
Answer:<\/strong> B) Troposphere
Explanation:<\/strong> All weather activities occur in the troposphere (up to ~12 km).<\/p>\n\n\n\n

89. The ozone layer is found in which atmospheric layer?
<\/mark><\/strong>A) Troposphere
B) Stratosphere
C) Mesosphere
D) Exosphere
Answer:<\/strong> B) Stratosphere
Explanation:<\/strong> The ozone layer lies between 15\u201335 km in the stratosphere.<\/p>\n\n\n\n

90. Acid rain is caused mainly by:
<\/mark><\/strong>A) CO\u2082 and CO
B) SO\u2082 and NOx
C) CH\u2084 and NH\u2083
D) CFCs and O\u2083
Answer:<\/strong> B) SO\u2082 and NOx
Explanation:<\/strong> Sulphur dioxide and nitrogen oxides form acids in the atmosphere, causing acid rain.<\/p>\n\n\n\n

91. The process of converting solid waste into manure or biogas using microbes is called:
<\/mark><\/strong>A) Landfilling
B) Composting
C) Incineration
D) Recycling
Answer:<\/strong> B) Composting
Explanation:<\/strong> Composting is a natural, eco-friendly waste management technique.<\/p>\n\n\n\n

92. Which ecosystem shows the highest net primary productivity (NPP)?
<\/mark><\/strong>A) Desert
B) Open ocean
C) Estuaries
D) Grassland
Answer:<\/strong> C) Estuaries
Explanation:<\/strong> Estuaries have rich nutrients and high productivity, more than rainforests per unit area.<\/p>\n\n\n\n

93. Which law states that \u201cno two species can occupy the same niche at the same time\u201d?
<\/mark><\/strong>A) Law of Limiting Factors
B) Gause\u2019s Competitive Exclusion Principle
C) Hardy-Weinberg Law
D) Lotka-Volterra Model
Answer:<\/strong> B) Gause\u2019s Competitive Exclusion Principle
Explanation:<\/strong> When two species compete for the same resource, one will be eliminated.<\/p>\n\n\n\n

94. The ecological pyramid that is always upright is:
<\/mark><\/strong>A) Pyramid of numbers
B) Pyramid of biomass
C) Pyramid of energy
D) Pyramid of productivity
Answer:<\/strong> C) Pyramid of energy
Explanation:<\/strong> Energy flow decreases at each trophic level, making energy pyramid always upright.<\/p>\n\n\n\n

95. Which of the following gases has the highest global warming potential (GWP)?
<\/mark><\/strong>A) CO\u2082
B) CH\u2084
C) N\u2082O
D) CFCs
Answer:<\/strong> D) CFCs
Explanation:<\/strong> CFCs have the highest GWP (thousands of times more than CO\u2082).<\/p>\n\n\n\n

96. Ecotone is a:
<\/mark><\/strong>A) Transitional zone between two ecosystems
B) Place where only one species lives
C) Core area of a biome
D) Artificial ecosystem
Answer:<\/strong> A) Transitional zone between two ecosystems
Explanation:<\/strong> Ecotones (e.g., mangroves) have high species diversity due to overlap of two ecosystems.<\/p>\n\n\n\n

97. Edge effect refers to:
<\/mark><\/strong>A) Low biodiversity at ecosystem boundaries
B) High biodiversity at ecotones
C) Absence of species at borders
D) Depletion of nutrients
Answer:<\/strong> B) High biodiversity at ecotones
Explanation:<\/strong> Ecotones show increased species richness, known as edge effect.<\/p>\n\n\n\n

98. The term \u201cSilent Spring\u201d was coined by Rachel Carson to highlight:
<\/mark><\/strong>A) Deforestation
B) Nuclear pollution
C) Pesticide pollution
D) Ozone depletion
Answer:<\/strong> C) Pesticide pollution
Explanation:<\/strong> Rachel Carson\u2019s 1962 book Silent Spring<\/em> warned against overuse of pesticides like DDT.<\/p>\n\n\n\n

99. Which of the following is NOT an ecosystem service?
<\/mark><\/strong>A) Pollination of crops
B) Climate regulation
C) Soil fertility maintenance
D) Industrial pollution
Answer:<\/strong> D) Industrial pollution
Explanation:<\/strong> Ecosystem services are benefits provided by ecosystems to humans; pollution is a threat, not a service.<\/p>\n\n\n\n

100. The term \u201cGaia Hypothesis\u201d (Earth as a self-regulating system) was proposed by:
<\/mark><\/strong>A) Charles Darwin
B) James Lovelock
C) E.P. Odum
D) Norman Myers
Answer:<\/strong> B) James Lovelock
Explanation:<\/strong> James Lovelock\u2019s Gaia Hypothesis suggests Earth functions as a self-regulating system.<\/p>\n","protected":false},"excerpt":{"rendered":"

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