AP Environmental Science Flashcards: Primary Productivity
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Review key ideas with interactive flashcards. This set includes 14 cards to help you master important concepts.
What is Respiration in the context of primary productivity?
Respiration is the process by which photosynthesizers use some of the captured solar energy for their own metabolic processes, releasing it as heat.
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What is Respiration in the context of primary productivity?
Respiration is the process by which photosynthesizers use some of the captured solar energy for their own metabolic processes, releasing it as heat.
What is Primary Productivity?
Primary productivity is the rate at which solar energy is converted into organic compounds via photosynthesis over a unit of time.
Define Net Primary Productivity (NPP).
Net primary productivity is the rate of energy storage by photosynthesizers in a given area, after subtracting the energy they lost to respiration.
How have photosynthesizers in aquatic ecosystems responded to the lack of visible light?
They have adapted special mechanisms to address the lack of visible light, allowing them to photosynthesize in low-light conditions.
Define Gross Primary Productivity (GPP).
Gross primary productivity is the total rate of photosynthesis in a given area, representing all the solar energy captured by producers.
How is energy transferred from photosynthesizers to other living organisms?
Energy is transferred when consumers eat the photosynthesizers (producers), moving the stored chemical energy up the food chain.
Why is productivity measured as a rate?
Productivity is measured as a rate (energy per area per time) because it describes the flow of energy through an ecosystem over a specific duration, not just a static amount.
What are the standard units used to measure primary productivity?
Productivity is measured in units of energy per unit area per unit time.
If an ecosystem's GPP is 20,000 $kcal/m^{2}/yr$ and producers use 12,000 $kcal/m^{2}/yr$ for respiration, what is the NPP?
The NPP is 8,000 $kcal/m^{2}/yr$, calculated by subtracting the energy lost to respiration from the GPP (20,000 - 12,000).
What is the primary factor limiting photosynthesis in aquatic ecosystems?
The absorption of light by water is the primary limiting factor, as it reduces the amount of visible light available for photosynthesis, especially at greater depths.
Provide a specific example of a unit for measuring primary productivity.
An example unit for measuring primary productivity is kilocalories per square meter per year ($kcal/m^{2}/yr$).
What is the relationship between Gross Primary Productivity (GPP) and Net Primary Productivity (NPP)?
NPP is what remains of GPP after accounting for the energy used by producers for their own respiration (NPP = GPP - Respiration).
What does Net Primary Productivity (NPP) represent for the other trophic levels in an ecosystem?
NPP represents the total amount of stored energy that is available to be transferred to consumers in an ecosystem.
How is solar energy initially acquired by living organisms in an ecosystem?
Solar energy is acquired by photosynthesizers (like plants and algae) who convert sunlight into organic compounds through the process of photosynthesis.