Ecology Of Ecosystem Processes 3 — Questions and Answers
Question 1: Which term describes the process by which water moves from the soil through a plant and evaporates from its leaves?
- Percolation
- Transpiration (Correct answer)
- Infiltration
- Precipitation
Correct answer: Transpiration
Transpiration is the evaporation of water from plant leaf surfaces, and together with soil evaporation forms evapotranspiration.
Question 2: In a food web, which group is responsible for the bulk of decomposition of dead organic matter?
- Herbivores
- Carnivores
- Detritivores and decomposers (Correct answer)
- Autotrophs
Correct answer: Detritivores and decomposers
Detritivores (e.g., millipedes, earthworms) fragment dead matter while decomposers (bacteria, fungi) chemically break it down.
Question 3: Which ecosystem process is directly responsible for moving carbon from the atmosphere into living organisms?
- Cellular respiration
- Decomposition
- Photosynthesis (Correct answer)
- Denitrification
Correct answer: Photosynthesis
Photosynthesis captures atmospheric CO₂ and fixes it into organic compounds, making it the primary entry point for carbon into the biotic world.
Question 4: What ecological term describes the ratio of net primary productivity to gross primary productivity?
- Trophic efficiency
- Lindeman efficiency
- Production efficiency (Correct answer)
- Assimilation efficiency
Correct answer: Production efficiency
Production efficiency (NPP/GPP) indicates what fraction of energy fixed by photosynthesis remains after autotrophic respiration.
Question 5: What is 'eutrophication' in aquatic ecosystems?
- Loss of species due to pollution
- Nutrient enrichment leading to algal blooms and oxygen depletion (Correct answer)
- Increase in water clarity from sediment removal
- Drop in primary productivity from UV exposure
Correct answer: Nutrient enrichment leading to algal blooms and oxygen depletion
Eutrophication occurs when excess nutrients (often nitrogen and phosphorus) cause rapid algal growth, which upon decomposition depletes dissolved oxygen.
Question 6: Which process converts nitrates back to atmospheric nitrogen gas in the nitrogen cycle?
- Nitrification
- Nitrogen fixation
- Ammonification
- Denitrification (Correct answer)
Correct answer: Denitrification
Denitrification, performed by anaerobic bacteria, converts nitrate (NO₃⁻) back to N₂ gas, completing the nitrogen cycle.
Question 7: In which ecosystem type is gross primary productivity typically highest per unit area?
- Open ocean
- Arctic tundra
- Tropical rainforest (Correct answer)
- Temperate grassland
Correct answer: Tropical rainforest
Tropical rainforests have the highest GPP per unit area due to abundant sunlight, warmth, and moisture year-round.
Ecology Of Ecosystem Processes 3
Which term describes the process by which water moves from the soil through a plant and evaporates from its leaves?