Environmental Biology MCQs January 8, 2026August 13, 2024 by u930973931_answers 50 min Score: 0 Attempted: 0/50 Subscribe 1. What is the term for the variety of life forms within a given ecosystem? (A) Ecology (B) Biomass (C) Biodiversity (D) Biome 2. Which of the following ecosystems has the highest biodiversity? (A) Coral reef (B) Tundra (C) Desert (D) Grassland 3. What is the main source of energy for most ecosystems? (A) Water (B) Soil (C) Sunlight (D) Air 4. What is the process by which plants convert carbon dioxide and water into glucose and oxygen? (A) Respiration (B) Nitrogen fixation (C) Fermentation (D) Photosynthesis 5. Which term describes the non-living components of an ecosystem? (A) Biotic (B) Abiotic (C) Autotrophic (D) Heterotrophic 6. What is the role of decomposers in an ecosystem? (A) To produce oxygen (B) To fix nitrogen (C) To break down dead organic matter (D) To compete with other organisms 7. Which of the following is an example of a keystone species? (A) Grass (B) Elephant (C) Ant (D) Algae 8. What is the term for the interaction where one organism benefits while the other is neither helped nor harmed? (A) Parasitism (B) Mutualism (C) Competition (D) Commensalism 9. Which biome is characterized by having the least precipitation? (A) Desert (B) Savanna (C) Tundra (D) Tropical rainforest 10. What is the process by which nitrogen is made available to plants in the soil? (A) Nitrogen fixation (B) Denitrification (C) Nitrification (D) Ammonification 11. Which of the following is an invasive species? (A) Bald eagle (B) American bison (C) Zebra mussel (D) Kangaroo 12. What is the term for the gradual process by which ecosystems change and develop over time? (A) Succession (B) Evolution (C) Speciation (D) Extinction 13. Which of the following best describes an autotroph? (A) An organism that consumes others for food (B) An organism that decomposes organic matter (C) An organism that produces its own food (D) An organism that lives on another organism 14. What is the term for a relationship between two species in which both benefit? (A) Parasitism (B) Commensalism (C) Mutualism (D) Competition 15. Which of the following is a primary consumer in an ecosystem? (A) Deer (B) Lion (C) Eagle (D) Shark 16. What is the term for the maximum population size that an environment can sustain? (A) Habitat (B) Population density (C) Ecological footprint (D) Carrying capacity 17. Which of the following is a density-dependent factor that affects population growth? (A) Disease (B) Natural disasters (C) Weather (D) Climate 18. What is the term for the role an organism plays in its environment? (A) Niche (B) Habitat (C) Biome (D) Trophic level 19. Which of the following processes removes carbon dioxide from the atmosphere? (A) Respiration (B) Photosynthesis (C) Combustion (D) Decomposition 20. Which of the following is a consequence of habitat fragmentation? (A) Increased biodiversity (B) Increased species extinction (C) Decreased edge effects (D) Enhanced ecosystem stability 21. Which of the following is an example of biomagnification? (A) Increase in atmospheric CO₂ (B) Eutrophication of lakes (C) Accumulation of DDT in a food chain (D) Acid rain formation 22. Which of the following best describes a primary producer? (A) A herbivore (B) A carnivore (C) A plant (D) A decomposer 23. What is the term for a species that has a disproportionately large impact on its ecosystem? (A) Invasive species (B) Indicator species (C) Keystone species (D) Endangered species 24. What is the main cause of coral bleaching? (A) Rising sea temperatures (B) Overfishing (C) Ocean acidification (D) Pollution 25. Which of the following is a consequence of deforestation? (A) Increase in carbon sequestration (B) Loss of biodiversity (C) Decrease in soil erosion (D) Increase in oxygen production 26. Which of the following is an example of a pioneer species? (A) Oak tree (B) Pine tree (C) Grass (D) Moss 27. Which of the following is a renewable resource? (A) Fossil fuels (B) Solar energy (C) Minerals (D) Metal ores 28. What is the process by which water vapor is released into the atmosphere from plants? (A) Evaporation (B) Condensation (C) Transpiration (D) Sublimation 29. Which of the following best describes an ecosystem? (A) A group of the same species (B) The interaction of living and non-living components without energy flow (C) The physical environment alone (D) A community of organisms interacting with their physical environment 30. What is the term for species that are native to a particular area and not found elsewhere? (A) Invasive species (B) Endemic species (C) Exotic species (D) Alien species 31. Which of the following is a direct result of eutrophication? (A) Coral bleaching (B) Algal blooms (C) Desertification (D) Acid rain 32. What is the role of nitrogen-fixing bacteria in the nitrogen cycle? (A) Convert ammonia to nitrites (B) Convert nitrogen gas to ammonia (C) Convert nitrates to nitrogen gas (D) Convert organic nitrogen to ammonia 33. What is the term for the process by which pollutants increase in concentration as they move up the food chain? (A) Bioaccumulation (B) Biodegradation (C) Biomagnification (D) Bioaugmentation 34. Which of the following is an example of a secondary consumer? (A) Grass (B) Rabbit (C) Fungus (D) Lion 35. What is the term for the reduction in genetic diversity in a population due to a reduction in population size? (A) Founder effect (B) Genetic drift (C) Gene flow (D) Bottleneck effect 36. Which of the following is a major contributor to global warming? (A) Methane (B) Water vapor (C) Nitrogen gas (D) Oxygen 37. What is the term for the sum of all the ecosystems on Earth? (A) Hydrosphere (B) Lithosphere (C) Biosphere (D) Atmosphere 38. Which of the following is a characteristic of a climax community? (A) High rate of succession (B) Low species diversity (C) Unstable environment (D) High biodiversity 39. What is the role of detritivores in an ecosystem? (A) To fix nitrogen (B) To compete with herbivores (C) To produce oxygen (D) To consume dead organic matter 40. What is the term for the movement of individuals into a population? (A) Emigration (B) Immigration (C) Migration (D) Translocation 41. Which of the following is a process that leads to the loss of soil nutrients? (A) Leaching (B) Weathering (C) Erosion (D) Sedimentation 42. Which of the following organisms is at the top of the food chain? (A) Producer (B) Tertiary consumer (C) Secondary consumer (D) Primary consumer 43. What is the term for a habitat that is being destroyed at an alarming rate? (A) Biodiversity hotspot (B) Ecological restoration (C) Urban ecosystem (D) Critical habitat 44. Which of the following is NOT a greenhouse gas? (A) Oxygen (B) Methane (C) Nitrous oxide (D) Carbon dioxide 45. What is the primary cause of the greenhouse effect? (A) Accumulation of greenhouse gases (B) Air pollution (C) Ozone depletion (D) Deforestation 46. Which of the following ecosystems is most affected by climate change? (A) Grassland (B) Desert (C) Tundra (D) Temperate forest 47. What is the term for the practice of planting trees to restore a damaged ecosystem? (A) Reforestation (B) Afforestation (C) Deforestation (D) Urbanization 48. Which of the following is a consequence of climate change? (A) Decrease in sea levels (B) Increase in biodiversity (C) Stabilization of ecosystems (D) Increased frequency of extreme weather events 49. What is the term for a species that has a significant impact on its community despite its low abundance? (A) Endangered species (B) Keystone species (C) Indicator species (D) Invasive species 50. What is the process of converting waste materials into reusable materials called? (A) Incineration (B) Composting (C) Recycling (D) Landfilling