AP Environmental Science · Unit 3 · Ecology & Interactions
Populations & Communities: every key term you need (+ practice quiz)
20 flashcard terms for AP Environmental Science Unit 3, written to match the course framework. Study them here, then drill them as interactive flashcards, or test yourself with the 5-question quiz — free, no account needed.
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Energy Flow Transfer of energy through ecosystem; from sun → producers → consumers; 10% efficiency between trophic levels.
Trophic Level Position in food chain: producers (1), primary consumers (2), secondary consumers (3), tertiary consumers (4).
Producer Autotroph that captures solar energy and converts to chemical energy; plants, algae, photosynthetic bacteria.
Consumer Heterotroph eating other organisms; primary eats plants, secondary eats primary, tertiary eats secondary.
Decomposer Organism breaking down dead matter (bacteria, fungi); returns nutrients to soil.
Biomass Total dry weight of living organisms; decreases at higher trophic levels (10% rule).
Bioaccumulation Toxin accumulation in organism over time; concentration increases with age.
Biomagnification Toxin concentration increases at higher trophic levels; top predators most contaminated.
Nutrient Cycle Movement of elements through organisms and environment; carbon, nitrogen, phosphorus, water cycles.
Carbon Cycle Carbon movement: atmosphere → producers → consumers → decomposers → atmosphere; fossil fuels interrupt.
Nitrogen Cycle Nitrogen fixation (N₂→NH₃), nitrification, assimilation, denitrification; bacteria essential.
Phosphorus Cycle Phosphorus cycling through rock weathering, soil, organisms; no gaseous form; limiting nutrient in freshwater.
Water Cycle Evaporation, transpiration, condensation, precipitation, infiltration, runoff; driven by solar energy.
NPK Nitrogen, phosphorus, potassium; essential plant macronutrients; fertilizer components.
Limiting Factor Resource or condition limiting population growth; often least abundant relative to need.
Primary Productivity Rate of biomass production by producers; GPP (gross) minus respiration = NPP (net).
Gross Primary Productivity Total energy fixed by producers through photosynthesis.
Net Primary Productivity Energy available to consumers after respiration costs; actual growth of producers.
Eutrophication Nutrient enrichment causing excess algae growth, oxygen depletion, dead zones in water.
Dead Zone Water area with insufficient dissolved oxygen; kills aquatic life; caused by algae decomposition.
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