Practice 100 Ecology MCQs with answers covering ecosystems, food chains, biodiversity, ecological succession, and environmental conservation. Ideal for students and competitive exams.
Ecology is a vital branch of biology that studies the relationships between living organisms and their environment, highlighting how ecosystems function and remain balanced. Understanding ecological concepts such as ecosystems, food chains, food webs, energy flow, biodiversity, ecological succession, and environmental conservation is essential for biology students and competitive exam aspirants. This article offers 100 well-structured Ecology MCQs with answers, designed to strengthen core concepts, support quick revision, and enhance exam performance. These ecology multiple choice questions are ideal for school exams, entrance tests, and general science preparation.
Below are 100 MCQs on Ecology, written in clear and correct English, suitable for school exams, competitive exams, and biology practice.
🌍 Ecology – 100 Multiple Choice Questions (MCQs) with Answers
1. Ecology is the study of:
A. Plants only
B. Animals only
C. Living organisms and their environment
D. Non-living things
Answer: C
2. The term “Ecology” was coined by:
A. Darwin
B. Mendel
C. Haeckel
D. Linnaeus
Answer: C
3. The place where an organism lives is called:
A. Niche
B. Habitat
C. Community
D. Population
Answer: B
4. A group of individuals of the same species is called:
A. Ecosystem
B. Community
C. Population
D. Biome
Answer: C
5. A community includes:
A. Only plants
B. Only animals
C. One species
D. Different populations
Answer: D
6. An ecosystem includes:
A. Only living organisms
B. Only non-living components
C. Living and non-living components
D. Only producers
Answer: C
7. Which of the following is a biotic factor?
A. Light
B. Water
C. Temperature
D. Bacteria
Answer: D
8. Which of the following is an abiotic factor?
A. Fungi
B. Animals
C. Temperature
D. Plants
Answer: C
9. Producers are also called:
A. Consumers
B. Decomposers
C. Autotrophs
D. Heterotrophs
Answer: C
10. Which organisms prepare their own food?
A. Consumers
B. Decomposers
C. Autotrophs
D. Parasites
Answer: C
11. Herbivores are:
A. Plant-eating animals
B. Meat-eating animals
C. Both plant and meat eaters
D. Decomposers
Answer: A
12. Carnivores are:
A. Plant eaters
B. Meat eaters
C. Omnivores
D. Producers
Answer: B
13. Omnivores eat:
A. Plants only
B. Animals only
C. Both plants and animals
D. Dead organisms only
Answer: C
14. Decomposers mainly include:
A. Plants
B. Animals
C. Bacteria and fungi
D. Insects
Answer: C
15. Decomposers help in:
A. Energy production
B. Recycling nutrients
C. Photosynthesis
D. Population growth
Answer: B
16. A food chain shows:
A. Energy flow
B. Water cycle
C. Nitrogen cycle
D. Oxygen cycle
Answer: A
17. The first trophic level is occupied by:
A. Herbivores
B. Carnivores
C. Producers
D. Decomposers
Answer: C
18. The second trophic level consists of:
A. Producers
B. Primary consumers
C. Secondary consumers
D. Decomposers
Answer: B
19. Food webs are:
A. Single food chains
B. Interconnected food chains
C. Cycles
D. Pyramids
Answer: B
20. Energy transfer between trophic levels is:
A. 100%
B. 50%
C. 10%
D. 90%
Answer: C
21. The 10% law was proposed by:
A. Darwin
B. Lindeman
C. Mendel
D. Haeckel
Answer: B
22. Ecological pyramids represent:
A. Number, biomass, or energy
B. Population only
C. Habitat only
D. Biomes
Answer: A
23. Pyramid of energy is always:
A. Inverted
B. Upright
C. Spindle-shaped
D. Irregular
Answer: B
24. Pyramid of biomass may be inverted in:
A. Forest ecosystem
B. Grassland ecosystem
C. Aquatic ecosystem
D. Desert ecosystem
Answer: C
25. Pyramid of numbers shows:
A. Energy flow
B. Biomass
C. Number of organisms
D. Nutrient cycle
Answer: C
26. Primary productivity refers to:
A. Energy used by consumers
B. Rate of biomass production by producers
C. Decomposition rate
D. Population growth
Answer: B
27. Gross Primary Productivity (GPP) is:
A. Total energy captured
B. Energy used in respiration
C. Net productivity
D. Energy lost
Answer: A
28. Net Primary Productivity (NPP) is:
A. GPP + respiration
B. GPP – respiration
C. Respiration – GPP
D. Energy lost
Answer: B
29. Which ecosystem has the highest productivity?
A. Desert
B. Grassland
C. Tropical rainforest
D. Tundra
Answer: C
30. The largest ecosystem on Earth is:
A. Forest
B. Grassland
C. Ocean
D. Desert
Answer: C
31. Biomes are large regions characterized by:
A. Climate and vegetation
B. Animals only
C. Soil only
D. Water only
Answer: A
32. Which biome has very low rainfall?
A. Forest
B. Desert
C. Grassland
D. Tundra
Answer: B
33. Tundra biome is characterized by:
A. High temperature
B. Permafrost
C. Heavy rainfall
D. Dense forest
Answer: B
34. Grasslands are mainly dominated by:
A. Trees
B. Shrubs
C. Grasses
D. Algae
Answer: C
35. Mangroves are found in:
A. Desert areas
B. Mountain regions
C. Coastal areas
D. Polar regions
Answer: C
36. Ecological succession is the process of:
A. Evolution
B. Community change over time
C. Population growth
D. Migration
Answer: B
37. Primary succession occurs on:
A. Bare rock
B. Grassland
C. Forest
D. Agricultural land
Answer: A
38. Secondary succession occurs after:
A. Volcanic eruption
B. Glacier retreat
C. Forest fire
D. Lava flow
Answer: C
39. Pioneer species in primary succession are:
A. Mosses
B. Lichens
C. Trees
D. Shrubs
Answer: B
40. The final stable community is called:
A. Pioneer community
B. Intermediate stage
C. Climax community
D. Temporary community
Answer: C
41. Population density is:
A. Total population
B. Individuals per unit area
C. Birth rate
D. Death rate
Answer: B
42. Natality refers to:
A. Death rate
B. Birth rate
C. Migration
D. Emigration
Answer: B
43. Mortality refers to:
A. Birth rate
B. Immigration
C. Death rate
D. Growth rate
Answer: C
44. Immigration means:
A. Leaving a population
B. Entering a population
C. Death
D. Birth
Answer: B
45. Emigration means:
A. Entering a population
B. Birth
C. Leaving a population
D. Growth
Answer: C
46. Population growth curve in unlimited resources is:
A. S-shaped
B. J-shaped
C. Straight
D. Irregular
Answer: B
47. Logistic growth curve is:
A. J-shaped
B. Exponential
C. S-shaped
D. Zigzag
Answer: C
48. Carrying capacity is the:
A. Maximum population supported
B. Birth rate
C. Death rate
D. Migration rate
Answer: A
49. Mutualism is a relationship where:
A. One benefits, other harmed
B. Both benefit
C. One benefits, other unaffected
D. Both harmed
Answer: B
50. Parasitism is a relationship where:
A. Both benefit
B. One benefits, other harmed
C. Both harmed
D. Both unaffected
Answer: B
51. Commensalism means:
A. Both benefit
B. One benefits, other unaffected
C. One harmed, other unaffected
D. Both harmed
Answer: B
52. Predation involves:
A. Cooperation
B. One organism killing another
C. Symbiosis
D. Mutual benefit
Answer: B
53. Competition occurs when organisms:
A. Cooperate
B. Share resources
C. Compete for same resources
D. Live separately
Answer: C
54. Ecotone is:
A. Boundary between two ecosystems
B. A population
C. A species
D. A biome
Answer: A
55. Edge effect refers to:
A. Reduced diversity
B. Increased diversity at ecotone
C. Population decline
D. Habitat loss
Answer: B
56. Biodiversity refers to:
A. Number of animals
B. Variety of life forms
C. Forest area
D. Climate change
Answer: B
57. Which region has highest biodiversity?
A. Polar regions
B. Deserts
C. Tropics
D. Tundra
Answer: C
58. Endemic species are:
A. Found everywhere
B. Found in one region only
C. Migratory
D. Extinct
Answer: B
59. Species richness refers to:
A. Population size
B. Number of species
C. Genetic diversity
D. Biomass
Answer: B
60. Keystone species have:
A. Minor role
B. No role
C. Disproportionately large impact
D. Negative impact
Answer: C
61. The main cause of biodiversity loss is:
A. Natural disasters
B. Habitat destruction
C. Migration
D. Competition
Answer: B
62. Deforestation leads to:
A. Increased biodiversity
B. Soil erosion
C. Climate stability
D. More rainfall
Answer: B
63. Greenhouse gases include:
A. Oxygen
B. Nitrogen
C. Carbon dioxide
D. Hydrogen
Answer: C
64. Global warming is caused by:
A. Ozone depletion
B. Greenhouse effect
C. Acid rain
D. Deforestation only
Answer: B
65. Ozone layer protects Earth from:
A. Infrared rays
B. UV rays
C. Visible light
D. Gamma rays
Answer: B
66. Acid rain is mainly caused by:
A. CO₂
B. SO₂ and NO₂
C. O₂
D. CH₄
Answer: B
67. Biomagnification refers to:
A. Decrease of pollutants
B. Increase of pollutants at higher trophic levels
C. Energy transfer
D. Population growth
Answer: B
68. DDT is an example of:
A. Biodegradable pollutant
B. Non-biodegradable pollutant
C. Greenhouse gas
D. Nutrient
Answer: B
69. Conservation of biodiversity means:
A. Destroying habitats
B. Protecting life forms
C. Exploiting resources
D. Ignoring species
Answer: B
70. In-situ conservation means:
A. Conservation in zoos
B. Conservation in natural habitat
C. Seed banks
D. Botanical gardens
Answer: B
71. Ex-situ conservation includes:
A. National parks
B. Wildlife sanctuaries
C. Zoos and botanical gardens
D. Biosphere reserves
Answer: C
72. Biosphere reserves are meant for:
A. Only conservation
B. Only research
C. Conservation and sustainable use
D. Tourism only
Answer: C
73. The Red Data Book contains:
A. Endangered species list
B. Common species
C. Extinct species only
D. Plants only
Answer: A
74. IUCN stands for:
A. International Union for Conservation of Nature
B. Indian Union for Climate Network
C. International United Climate Network
D. Indian Union of Nature
Answer: A
75. Sustainable development means:
A. Development without harming environment
B. Fast development
C. Industrial growth only
D. Resource exploitation
Answer: A
76. Renewable resources are:
A. Limited
B. Exhaustible
C. Replenishable
D. Non-living
Answer: C
77. Non-renewable resources include:
A. Wind
B. Solar energy
C. Coal
D. Water
Answer: C
78. Ecosystem stability depends on:
A. Species diversity
B. Climate only
C. Soil only
D. Water only
Answer: A
79. The nitrogen cycle involves:
A. Only plants
B. Only animals
C. Atmosphere, soil, and organisms
D. Water only
Answer: C
80. Nitrogen fixation converts:
A. N₂ to ammonia
B. Ammonia to nitrate
C. Nitrate to nitrogen
D. Oxygen to nitrogen
Answer: A
81. Which bacteria fix nitrogen?
A. Rhizobium
B. Lactobacillus
C. E. coli
D. Streptococcus
Answer: A
82. Carbon cycle maintains balance of:
A. Oxygen
B. Nitrogen
C. Carbon dioxide
D. Hydrogen
Answer: C
83. Water cycle includes:
A. Evaporation
B. Condensation
C. Precipitation
D. All of these
Answer: D
84. Primary consumers feed on:
A. Carnivores
B. Producers
C. Decomposers
D. Secondary consumers
Answer: B
85. Secondary consumers feed on:
A. Producers
B. Herbivores
C. Plants
D. Decomposers
Answer: B
86. Tertiary consumers are usually:
A. Herbivores
B. Primary consumers
C. Top carnivores
D. Decomposers
Answer: C
87. Energy flow in ecosystem is:
A. Cyclic
B. Unidirectional
C. Bidirectional
D. Random
Answer: B
88. Nutrient cycles are:
A. Linear
B. Unidirectional
C. Cyclic
D. One-time
Answer: C
89. Detritus food chain starts with:
A. Producers
B. Herbivores
C. Dead organic matter
D. Carnivores
Answer: C
90. Grazing food chain starts with:
A. Producers
B. Decomposers
C. Carnivores
D. Parasites
Answer: A
91. Ecological balance means:
A. Equal population
B. Stable interaction among organisms
C. No predators
D. No competition
Answer: B
92. Habitat fragmentation leads to:
A. Increased biodiversity
B. Species extinction
C. Stable ecosystems
D. Population growth
Answer: B
93. Overpopulation causes:
A. Resource depletion
B. Ecosystem balance
C. Biodiversity increase
D. Climate stability
Answer: A
94. Pollution is:
A. Beneficial
B. Harmless
C. Undesirable change in environment
D. Natural balance
Answer: C
95. Noise pollution affects:
A. Hearing
B. Vision
C. Taste
D. Smell
Answer: A
96. Water pollution affects:
A. Aquatic life
B. Soil only
C. Air only
D. Forest only
Answer: A
97. Soil erosion is mainly caused by:
A. Wind and water
B. Fire
C. Animals
D. Microbes
Answer: A
98. Afforestation means:
A. Cutting trees
B. Planting trees
C. Removing forest
D. Burning forest
Answer: B
99. Conservation helps in:
A. Extinction
B. Environmental protection
C. Pollution increase
D. Resource depletion
Answer: B
100. Ecology helps us understand:
A. Nature balance
B. Human evolution
C. Cell biology
D. Genetics only
Answer: A
