Ecosystem ecology – structure, function, energy flow, mineral cycling - Question Bank

1. Which of the following best describes the function of an ecosystem?
A) The collection of all species in a habitat.
B) The physical structure of the environment.
C) The dynamic processes of energy and matter transfer.
D) The geographical boundaries of a biological community.
2. The overall efficiency of energy transfer between the producer level and the primary consumer level is approximately:
A) 0.1%
B) 1%
C) 10%
D) 50%
3. If a lake ecosystem is polluted with excess phosphates, what is a likely consequence?
A) Increased dissolved oxygen levels.
B) Decreased algal growth.
C) Algal blooms and potential oxygen depletion.
D) Increased biodiversity of fish species.
4. Which of the following is a key process in the water cycle that returns water vapor to the atmosphere from plants?
A) Evaporation
B) Condensation
C) Transpiration
D) Precipitation
5. What role do sulfur bacteria play in the sulfur cycle?
A) They convert sulfates to hydrogen sulfide.
B) They convert hydrogen sulfide to sulfates.
C) They fix atmospheric nitrogen.
D) They photosynthesize using sulfur compounds.
6. The term 'standing crop' in ecosystem ecology refers to:
A) The total energy available at a trophic level.
B) The biomass of organisms present at a particular time.
C) The rate of nutrient uptake by plants.
D) The rate of decomposition in the soil.
7. Which component of an ecosystem is responsible for converting dead organic matter back into inorganic nutrients?
A) Producers
B) Primary consumers
C) Secondary consumers
D) Decomposers
8. A food web is a more realistic representation of energy flow than a food chain because:
A) It shows only producers.
B) It depicts multiple feeding relationships.
C) It illustrates nutrient cycling.
D) It emphasizes the 10% law.
9. Respiration in living organisms primarily releases:
A) Energy
B) Carbon dioxide
C) Water
D) All of the above
10. The process of photosynthesis is represented by the equation:
A) C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy
B) 6CO2 + 6H2O + Light Energy → C6H12O6 + 6O2
C) N2 + 3H2 → 2NH3
D) NH3 + O2 → NO2- + H2O
11. Which type of ecosystem typically has the highest net primary productivity per unit area?
A) Desert
B) Temperate grassland
C) Tropical rainforest
D) Arctic tundra
12. What is the role of mycorrhizal fungi in nutrient cycling?
A) They fix atmospheric nitrogen.
B) They break down dead organic matter.
C) They enhance phosphorus uptake by plants.
D) They convert nitrates to nitrogen gas.
13. In aquatic ecosystems, the primary producers are often:
A) Large trees
B) Phytoplankton and algae
C) Decomposers
D) Zooplankton
14. The process of ammonification in the nitrogen cycle involves:
A) Conversion of atmospheric N2 to ammonia.
B) Conversion of organic nitrogen to ammonia.
C) Conversion of ammonia to nitrites.
D) Conversion of nitrates to atmospheric N2.
15. Which element's cycle involves significant atmospheric gas exchange?
A) Phosphorus
B) Sulfur
C) Carbon and Nitrogen
D) Potassium
16. Biogeochemical cycles are essential for:
A) Increasing the temperature of the ecosystem.
B) Recycling essential elements and nutrients.
C) Increasing the biomass of producers.
D) Maintaining atmospheric pressure.
17. What is the main consequence of the unidirectional energy flow in an ecosystem?
A) Energy is lost as heat at each trophic level.
B) Energy is recycled back to producers.
C) Energy accumulates at higher trophic levels.
D) Energy input from decomposers is highest.
18. The term 'trophic level' refers to:
A) The physical habitat of an organism.
B) The position an organism occupies in a food chain.
C) The rate of reproduction of a species.
D) The environmental tolerance of an organism.
19. Which of the following is a decomposer found in most terrestrial ecosystems?
A) A rabbit
B) A mushroom
C) A snake
D) A sunflower
20. In a grassland ecosystem, what would be an example of a primary consumer?
A) Lion
B) Grasshopper
C) Hawk
D) Fungus
21. In a forest ecosystem, what would be an example of a producer?
A) Deer
B) Wolf
C) Oak tree
D) Earthworm
22. The function of an ecosystem is primarily related to:
A) The number of species present.
B) The physical size of the ecosystem.
C) Energy flow and nutrient cycling.
D) The geographic location.
23. The structure of an ecosystem refers to:
A) The rate of energy flow.
B) The biodiversity and trophic composition.
C) The rate of mineral cycling.
D) The climatic conditions.
24. What is the main function of detritivores in an ecosystem?
A) To photosynthesize and produce organic matter.
B) To break down large organic particles into smaller pieces.
C) To convert inorganic nutrients into organic forms.
D) To release energy through aerobic respiration.
25. Eutrophication in aquatic ecosystems is often caused by excessive input of which nutrient?
A) Carbon
B) Nitrogen and Phosphorus
C) Oxygen
D) Potassium
26. Which process is largely absent in the phosphorus cycle compared to the carbon or nitrogen cycle?
A) Uptake by producers
B) Release by decomposers
C) Atmospheric phase
D) Weathering of rocks
27. The primary reservoir for phosphorus in most ecosystems is:
A) The atmosphere
B) Oceans and sedimentary rocks
C) Living organisms
D) Surface water
28. Denitrification is the process by which:
A) Nitrates are converted back to atmospheric nitrogen.
B) Ammonia is converted to nitrites.
C) Organic nitrogen is converted to ammonia.
D) Atmospheric nitrogen is converted to ammonia.
29. Which bacteria are primarily responsible for nitrification?
A) Nitrobacter and Nitrosomonas
B) Rhizobium
C) Azotobacter
D) Clostridium
30. Nitrogen fixation is the process of converting atmospheric nitrogen (N2) into:
A) Ammonia (NH3)
B) Nitrates (NO3-)
C) Organic nitrogen compounds
D) All of the above
31. What is the role of decomposers in the carbon cycle?
A) They absorb CO2 from the atmosphere.
B) They release CO2 into the atmosphere through respiration.
C) They convert organic carbon into inorganic carbon.
D) They fix atmospheric nitrogen into organic compounds.
32. The process by which carbon dioxide is removed from the atmosphere and converted into organic compounds is called:
A) Respiration
B) Combustion
C) Photosynthesis
D) Decomposition
33. Which of the following is NOT a type of mineral cycling (biogeochemical cycle)?
A) Carbon cycle
B) Nitrogen cycle
C) Energy cycle
D) Phosphorus cycle
34. A pyramid of energy represents:
A) The biomass at each trophic level.
B) The number of individuals at each trophic level.
C) The amount of energy available at each trophic level.
D) The rate of nutrient cycling at each trophic level.
35. The '10% law' in ecology refers to:
A) The percentage of producers that are consumed.
B) The energy transfer efficiency between trophic levels.
C) The percentage of decomposers in an ecosystem.
D) The proportion of water recycled in an ecosystem.
36. What is the approximate percentage of energy transferred from one trophic level to the next in most ecosystems?
A) 50-60%
B) 30-40%
C) 10-20%
D) 70-80%
37. Net Primary Productivity (NPP) represents:
A) The total energy captured by producers.
B) The energy available to consumers after producers respire.
C) The energy lost through decomposition.
D) The energy flow to the decomposer trophic level.
38. The rate at which producers convert light energy into chemical energy is known as:
A) Respiration rate
B) Net primary productivity
C) Gross primary productivity
D) Decomposition rate
39. What is the primary source of energy for most ecosystems on Earth?
A) Geothermal energy
B) Chemical energy from rocks
C) Solar energy
D) Electrical energy from lightning
40. The flow of energy in an ecosystem is:
A) Cyclical
B) Unidirectional
C) Bidirectional
D) Intermittent
41. Which group of organisms is crucial for nutrient recycling in an ecosystem?
A) Large herbivores
B) Top predators
C) Decomposers and detritivores
D) Photosynthetic bacteria
42. Organisms that break down dead organic matter are called:
A) Producers
B) Consumers
C) Decomposers
D) Detritivores
43. Carnivores that feed on herbivores are known as:
A) Primary consumers
B) Secondary consumers
C) Decomposers
D) Autotrophs
44. Herbivores are classified as which type of consumer?
A) Primary consumers
B) Secondary consumers
C) Tertiary consumers
D) Apex predators
45. Which trophic level consists of organisms that feed on producers?
A) Primary consumers
B) Secondary consumers
C) Tertiary consumers
D) Decomposers
46. What is the term for organisms that produce their own food, usually through photosynthesis?
A) Consumers
B) Decomposers
C) Producers
D) Omnivores
47. Abiotic components of an ecosystem include:
A) Plants and animals
B) Fungi and bacteria
C) Temperature, rainfall, and soil pH
D) Algae and plankton
48. Which of the following represents the biotic component of an ecosystem?
A) Sunlight
B) Soil
C) Water
D) Producers, consumers, and decomposers
49. What is the primary definition of an ecosystem in ecological terms?
A) A community of living organisms interacting with each other.
B) A geographical area with specific climatic conditions.
C) A community of living organisms and their physical environment interacting as a system.
D) The total biodiversity of a region.
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