AP Environmental Science Unit 1 Terms

Quizlet set for 101 terms and definitions from Unit 1 - Ecosystems, Biomes, Cycles, Productivity.

Primary productivity

Rate at which producers convert solar energy into organic compounds over time (photosynthesis rate per area).

Gross primary productivity (GPP)

Total solar energy captured by producers and fixed as chemical energy (glucose).

Energy producers use for cellular respiration and maintenance that is not stored as biomass.

Net primary productivity (NPP)

Energy/biomass available to consumers; NPP = GPP − RL.

Ecological efficiency (producer level)

Small fraction of incoming sunlight captured; ~1% becomes GPP and ~0.4% becomes NPP.

10% rule (energy)

About 10% of energy transfers to the next trophic level; ~90% is used or lost as heat.

10% rule (biomass)

Only about 10% of biomass at one trophic level can be supported at the next level.

Trophic level

Position in a food chain (producer, primary consumer, secondary consumer, tertiary consumer).

Primary consumer

Herbivore that eats producers.

Secondary consumer

Carnivore/omnivore that eats herbivores.

Tertiary consumer

Predator feeding on secondary consumers (often apex).

First law of thermodynamics

Energy is conserved; it changes form but is neither created nor destroyed.

Second law of thermodynamics

Every energy transfer loses usable energy as heat; less usable energy at higher trophic levels.

Factors increasing NPP

High water availability, warm temperatures, and nutrient availability.

Trophic cascade

Top-down effect where predators indirectly benefit lower trophic levels by controlling herbivores.

Ecosystem

All living and nonliving components interacting in an area.

Community

All living organisms in an area.

Population

Individuals of the same species in an area.

Biome

Regional community of plants/animals defined by long-term temperature and precipitation.

Weather

Short-term atmospheric conditions.

Climate

Long-term average weather in a location.

Mutualism

Symbiosis where both species benefit (e.g., coral and algae).

Commensalism

One species benefits, the other is unaffected.

Parasitism

One species benefits at the other’s expense without immediate killing (parasites).

Parasitoid

Lays eggs in/on host; larvae consume and usually kill host.

Predation

One organism consumes another for energy.

Competition

Organisms vie for limited resources, reducing population sizes.

Resource partitioning

Species reduce competition by using the same resource in different ways/times/places.

Temporal partitioning

Using resources at different times (e.g., day vs. night).

Spatial partitioning

Using different areas or depths of a habitat.

Morphological partitioning

Using resources differently due to body differences.

Shifting biomes

Biomes shift geographically as climate changes (e.g., boreal forest moves poleward).

Tropical rainforest

Warm, very wet, dense vegetation; nutrient-poor soils due to rapid uptake/competition.

Temperate rainforest

Cool to mild with high rainfall, rich foliage; can have rich soils and conifer/broadleaf mix.

Temperate seasonal forest (deciduous)

Seasonal temperature, moderate precipitation; nutrient-rich loamy soils from leaf litter.

Shrubland (chaparral)

Open, woody shrubs/short trees; low nutrients due to heat and dryness.

Temperate grassland (prairie/steppe)

Semiarid, few trees, very fertile deep soils from grass root turnover.

Savanna

Warm with distinct wet/dry seasons; grasses with scattered trees; low soil nutrients, high competition.

Desert

Driest biome, sparse drought-adapted vegetation; nutrient-poor soils from low organic matter/weathering.

Tundra

Coldest biome, low precipitation, permafrost, short growing season, limited nutrients.

Taiga (boreal forest)

Cold, conifer-dominated, nutrient-poor soils from low decomposition rates.

Latitude–biome pattern

Tundra/boreal at high latitudes, temperate at mid-latitudes, tropical near the equator.

Depth (light penetration)

Controls photosynthesis below surface; defines photic vs. aphotic zones.

Temperature (aquatic)

Warmer water holds less dissolved oxygen, supporting fewer organisms.

Salinity

Salt concentration determines species tolerance and water use (fresh vs. estuary vs. ocean).

Flow

Water movement shapes habitat, oxygenation, and species survival.

Dissolved oxygen (DO)

Oxygen in water; generally higher in fast-flowing rivers due to mixing.

River

Flowing freshwater with high DO and sediment transport; forms fertile deltas/floodplains.

Lake

Standing freshwater; key drinking source with distinct light/plant zones.

Littoral zone

Shallow, near-shore area with rooted emergent plants.

Limnetic zone

Open-water, well-lit zone where phytoplankton photosynthesize; few rooted plants.

Profundal zone

Deep, dark lake zone with no photosynthesis.

Benthic zone

Bottom sediments; nutrient-rich, supports invertebrates.

Wetland

Ground is submerged/saturated part of the year; supports emergent plants and provides flood control, groundwater recharge, and pollutant filtration.

Swamp

Forested wetland (woody plants).

Marsh

Non-woody wetland dominated by reeds/cattails.

Bog

Wetland with highly acidic soils, often sphagnum-rich.

Estuary

Where rivers meet the ocean; brackish water, high productivity from nutrient-rich sediments.

Salt marsh

Temperate estuary habitat, crucial nursery for fish/shellfish.

Mangrove swamp

Tropical estuary habitat with stilt-rooted trees that stabilize shorelines and offer nursery habitat.

Coral reef

Warm, shallow, most diverse marine biome; coral–algae mutualism and calcium carbonate reef building.

Intertidal zone

Shoreline between high/low tide; organisms adapt to wave action and desiccation.

Open ocean

Low productivity per area; photic zone allows photosynthesis, aphotic is too deep for light; ocean biota act as a major CO2 sink.

Carbon sink

Reservoir taking in more carbon than it releases (ocean, plants, soils).

Carbon source

Reservoir releasing more carbon than it absorbs (FF combustion, deforestation, animal agriculture CH₄).

Photosynthesis

CO₂ + H₂O → C₆H₁₂O₆ + O₂; pulls CO₂ from air/water into biomass.

Cellular respiration

C₆H₁₂O₆ + O₂ → CO₂ + H₂O + energy; returns CO₂ to atmosphere.

Direct exchange (air–sea)

Rapid two-way CO₂ exchange between atmosphere and ocean surface waters.

Ocean acidification

Rising oceanic CO₂ lowers pH.

Marine calcification

Coral and shell-formers use dissolved C to build CaCO₃ skeletons/shells.

Sedimentation

Carbonate and organic particles settle to the seafloor, forming sediments.

Burial

Long-term geological storage of carbon in sedimentary rocks and fossil fuels.

Extraction and combustion

Mining/drilling fossil fuels and burning them; adds CO₂ to atmosphere.

Main reservoir (N)

Atmosphere (N₂ gas), biologically unavailable without conversion.

Nitrogen fixation (biotic)

Soil or symbiotic bacteria convert N₂ to NH₃/NH₄⁺; legumes host rhizobacteria in root nodules.

Nitrogen fixation (abiotic/synthetic)

Human processes (e.g., fertilizer production; FF combustion producing reactive N) yield NH₃/NOₓ for ecosystems.

Nitrification

Soil bacteria convert NH₄⁺ → NO₂⁻ → NO₃⁻.

Assimilation (N)

Plants take up NH₃/NH₄⁺/NO₃⁻; animals obtain N by eating.

Ammonification

Decomposers convert organic N in waste/dead biomass to NH₃/NH₄⁺.

Denitrification

Anaerobic bacteria convert NO₃⁻ to gaseous forms (N₂O, N₂), returning N to atmosphere.

Leaching (nitrate)

NO₃⁻ is water-soluble and can be carried from soils into groundwater/surface waters.

Ammonia volatilization

Excess NH₃ from fertilizers enters the atmosphere.

Nitrous oxide (N₂O)

Greenhouse gas produced during denitrification; warms climate.

Main reservoirs (P)

Rocks and sediments containing phosphate minerals; no significant atmospheric gas phase.

Weathering (P)

Wind/rain break down rocks, releasing phosphate (PO₄³⁻) to soils and waters.

Limiting nutrient (P)

Slow cycling and low solubility make P limiting for plant growth in many ecosystems.

Assimilation (P)

Plants absorb phosphate; animals obtain P by feeding.

Excretion/decomposition (P)

Returns phosphate to soils; low solubility leads to sedimentation.

Sedimentation (P)

Insoluble phosphates settle as sediments, forming long-term reservoirs.

Geological uplift

Tectonics raise sedimentary rocks, exposing P to weathering again.

Anthropogenic P sources

Mining phosphates for fertilizers/detergents adds P to waters via runoff and wastewater.

Eutrophication

Excess N and P fuel algal blooms that block light; decomposition consumes dissolved oxygen, causing fish kills and a positive feedback of further O2 loss.

Largest water reservoir

The ocean.

Freshwater reservoirs

Ice caps/glaciers and groundwater aquifers (key usable freshwater).

Evaporation

Liquid water becomes vapor due to solar energy.

Transpiration

Plants pull water from roots to leaves; water exits stomata as vapor.

Evapotranspiration

Combined water vapor flux from evaporation and transpiration.

Runoff

Precipitation flowing over land into surface waters.

Infiltration

Water percolating into soil to recharge groundwater; depends on soil permeability.

Aquifer

Underground water-bearing rock/sediment storing groundwater.