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Flip to reveal answersDefine productivity in ecosystems.
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All 19 Flashcards — Productivity
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Question
Define productivity in ecosystems.
Answer
Productivity is the rate at which new biomass is produced in an ecosystem, usually by producers through photosynthesis.
💡 Hint
Rate of biomass production
Question
State what productivity measures: a total or a rate?
Answer
Productivity measures a rate: how quickly new biomass is produced.
💡 Hint
It is a rate
Question
Define productivity.
Answer
Productivity is the rate at which new biomass is produced in an ecosystem.
💡 Hint
Rate of biomass
Question
State the difference between gross and net productivity.
Answer
Gross productivity is total energy captured; net productivity is what remains after respiration losses.
💡 Hint
Before vs after respiration
Question
Define gross productivity (GP).
Answer
Gross productivity is the total biomass or energy gained by producers through photosynthesis before losses to respiration.
💡 Hint
Total captured
Question
State the relationship between GP, NP, and respiration.
Answer
Net productivity equals gross productivity minus respiration: NP = GP − R.
💡 Hint
Subtract respiration
Question
State the formula for net productivity.
Answer
NP = GP − R.
💡 Hint
Subtract respiration
Question
Define net productivity (NP).
Answer
Net productivity is the biomass or energy remaining after respiration losses, available for growth, reproduction, and transfer to the next trophic level.
💡 Hint
Available after respiration
Question
State the core relationship between NP, GP and respiration.
Answer
Net productivity equals gross productivity minus respiration: NP = GP − R.
💡 Hint
NP = GP − R
Question
Explain what respiration represents in productivity calculations.
Answer
Respiration represents energy used by organisms for metabolism and life processes, released mainly as heat.
💡 Hint
Energy used + heat
Question
Explain why net productivity decreases at higher trophic levels.
Answer
Energy is lost as heat through respiration at each transfer, so less energy remains to form new biomass at higher levels.
💡 Hint
Heat loss each transfer
Question
State which type of productivity is available to consumers and why.
Answer
Net productivity is available to consumers because it is the biomass remaining after producers use energy for respiration.
💡 Hint
Consumers use NP
Question
What type of organisms are responsible for most productivity?
Answer
Producers such as plants and algae are responsible for most productivity because they convert sunlight into chemical energy through photosynthesis.
💡 Hint
Plants and algae
Question
Why is productivity described as a rate rather than a total?
Answer
Productivity measures how quickly new biomass is produced over time, not the total amount present.
💡 Hint
Speed of production
Question
Explain what happens to energy lost through respiration.
Answer
Energy used in respiration is released as heat to the environment and cannot be passed to the next trophic level.
💡 Hint
Lost as heat
Question
Which productivity value is transferred to the next trophic level?
Answer
Net productivity is transferred because it represents biomass remaining after respiration.
💡 Hint
Only NP transfers
Question
Give one reason why productivity limits food chain length.
Answer
Energy is lost at each trophic transfer, so progressively less energy is available to support higher trophic levels.
💡 Hint
Less energy higher up
Question
Explain why high respiration reduces net productivity.
Answer
More energy is used for life processes and released as heat, leaving less energy available to form new biomass.
💡 Hint
More respiration = less NP
Question
State one factor that can increase productivity in an ecosystem.
Answer
High light availability, suitable temperature, and sufficient nutrients can all increase productivity.
💡 Hint
Light, heat, nutrients
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Topic 2.5 hub
Flows of energy and matter
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