AP Environmental Science: 300 Terms with Real Cases

The free-response marks go to the mechanism and the example, not to the definition alone.

300 cardsLast updated 2026-08-31

Add every card on the free plan. Importing runs no AI generation and spends no AI credits. You'll need a Memly account.

Defining eutrophication earns nothing on its own. The point comes from saying that nutrient enrichment drives an algal bloom, that decomposing algae consume the oxygen, and that fish die in the resulting low-oxygen zone. Environmental science is a vocabulary course only on the surface. What it actually tests is whether you can name a cause, trace it to an effect, and attach a real case. This deck is 300 cards, one term per card, with the back cut into three fixed lines. "Meaning" defines the term in a sentence. "Why it matters" says what it causes, prevents or explains. "Example" gives one real case, place or measurable consequence. The sections follow the course: ecosystems and biodiversity, populations, earth systems and resources, land and water use, energy, and pollution and global change. No country's current statistic appears. Emissions figures and renewable shares change every year and a memorised number goes stale without warning, while the mechanism behind it does not. Once the deck is on a spaced-repetition schedule, the terms you can already explain stop coming back and the ones whose mechanism you keep reversing return until they stop being guesswork.

What happens when you add it

1
The button opens Memly and the whole deck lands in your account.
2
Each card gets its own schedule, based on how well you actually recall it.
3
They are your cards afterwards — rewrite, delete or reorganize them freely.

What's inside

Showing 100 representative cards from the full 300-card deck.

Front	Back
Ecosystem	Meaning: A community of organisms together with the physical environment they interact with. Why it matters: It is the unit at which energy flow and nutrient cycling are studied. Example: A pond, including its water, sediment, plants, fish and bacteria.
Producer	Meaning: An organism that makes its own food from inorganic sources. Why it matters: Producers capture the energy that every other trophic level depends on. Example: Phytoplankton, which support almost all open-ocean food webs.
Decomposer	Meaning: An organism that breaks down dead material into simpler compounds. Why it matters: Decomposition returns nutrients to the soil so that producers can reuse them. Example: Fungi breaking down leaf litter on a forest floor.
Food web	Meaning: A network of interconnected food chains in a community. Why it matters: It shows how the loss of one species can affect many others. Example: Removing sea otters allows urchins to multiply and destroy kelp forests.
Gross primary productivity	Meaning: The total rate at which producers capture energy. Why it matters: It sets the ceiling on how much energy can enter the ecosystem. Example: The total photosynthesis of a tropical rainforest canopy over a year.
Carbon cycle	Meaning: The movement of carbon among the atmosphere, oceans, land and living things. Why it matters: Human interference with it is the main driver of climate change. Example: Burning coal transfers carbon from a long-term reservoir to the atmosphere.
Nitrogen cycle	Meaning: The movement of nitrogen among the atmosphere, soil and organisms. Why it matters: Nitrogen availability limits plant growth in many ecosystems. Example: Legume roots hosting bacteria that convert atmospheric nitrogen to usable forms.
Denitrification	Meaning: The conversion of nitrates back into atmospheric nitrogen. Why it matters: It closes the nitrogen cycle and removes nitrogen from soils. Example: Bacteria in waterlogged soils releasing nitrogen gas from a flooded field.
Water cycle	Meaning: The continuous movement of water through evaporation, condensation and precipitation. Why it matters: It redistributes fresh water and shapes the climate of every region. Example: Transpiration from the Amazon forest generating rainfall downwind.
Biome	Meaning: A large region defined by its climate and characteristic vegetation. Why it matters: Biomes explain why similar communities appear on different continents. Example: Grasslands occurring in North America, Africa and Eurasia at similar latitudes.
Temperate deciduous forest	Meaning: A biome with warm summers, cold winters and trees that shed their leaves. Why it matters: Its rich leaf litter builds fertile soils. Example: Much of eastern North America and western Europe was once this biome.
Desert	Meaning: A biome defined by very low precipitation. Why it matters: Slow recovery from disturbance makes desert soils easy to damage. Example: Vehicle tracks in desert crust remaining visible for decades.
Aquatic life zones	Meaning: Divisions of water bodies based on depth, light and salinity. Why it matters: Light availability sets where photosynthesis is possible. Example: The photic zone of the ocean, where nearly all marine production occurs.
Ecological succession	Meaning: The gradual change in the species composition of a community over time. Why it matters: It explains how ecosystems recover after disturbance. Example: Bare rock progressing to lichens, then soil, then shrubs and trees.
Secondary succession	Meaning: Succession on land where soil remains after a disturbance. Why it matters: It is much faster than primary succession because the seed bank survives. Example: An abandoned farm field returning to forest over several decades.
Ecological niche	Meaning: The full role a species plays in its ecosystem. Why it matters: Species with identical niches cannot coexist indefinitely. Example: Warblers feeding at different heights in the same spruce tree.
Specialist species	Meaning: A species with a narrow niche and specific requirements. Why it matters: Specialists are highly vulnerable to habitat change. Example: The giant panda depending almost entirely on bamboo.
Resource partitioning	Meaning: The division of a shared resource so that competitors can coexist. Why it matters: It reduces direct competition and allows greater diversity. Example: Lizards on the same island feeding at different times of day.
Mutualism	Meaning: A symbiosis in which both species benefit. Why it matters: Mutualisms underpin many ecosystems, including pollination and nutrient uptake. Example: Bees gaining nectar while transferring pollen between flowers.
Keystone species	Meaning: A species whose effect on a community is far larger than its abundance suggests. Why it matters: Removing it causes disproportionate change throughout the ecosystem. Example: Sea otters keeping urchin numbers low and preserving kelp forests.
Biodiversity	Meaning: The variety of life at the genetic, species and ecosystem levels. Why it matters: Greater diversity generally increases resilience to disturbance. Example: A coral reef supporting thousands of species in a small area.
Habitat fragmentation	Meaning: The division of a continuous habitat into smaller isolated patches. Why it matters: It reduces population sizes and blocks movement between them. Example: Roads splitting a forest so that large mammals cannot cross safely.
Island biogeography	Meaning: The theory relating species number on an island to its size and isolation. Why it matters: It guides how nature reserves are sized and connected. Example: Larger islands closer to the mainland supporting more species than small remote ones.
Population	Meaning: A group of individuals of one species living in the same area. Why it matters: It is the level at which growth, density and limits are measured. Example: All the brook trout in a single stream system.
Population dispersion	Meaning: The spatial pattern in which individuals are arranged. Why it matters: The pattern reveals whether resources are patchy or individuals repel each other. Example: Clumped distribution of trees around a water source in a dry landscape.
Exponential growth	Meaning: Growth in which population increases by a constant proportion each interval. Why it matters: It produces a J-shaped curve and cannot continue indefinitely. Example: Bacteria doubling repeatedly in a fresh culture medium.
Carrying capacity	Meaning: The largest population an environment can support indefinitely. Why it matters: Exceeding it damages the resource base and lowers it further. Example: Overgrazed rangeland supporting fewer animals after the herd has crashed.
Density-dependent factor	Meaning: A limiting factor whose effect strengthens as density rises. Why it matters: It stabilises populations near carrying capacity. Example: Disease spreading faster through a crowded population.
Biotic potential	Meaning: The maximum rate at which a population could grow under ideal conditions. Why it matters: It sets the upper bound that environmental resistance reduces. Example: A single housefly pair producing enormous numbers if none died.
r-selected species	Meaning: A species with many offspring, little parental care and a short life. Why it matters: These species colonise disturbed areas quickly. Example: Dandelions producing thousands of wind-dispersed seeds.
Type one survivorship	Meaning: A pattern of low mortality until old age. Why it matters: It is typical of species with heavy parental care. Example: Large mammals whose young are protected until maturity.
Demography	Meaning: The statistical study of human populations. Why it matters: It provides the data used to project future population size and needs. Example: Census data used to plan school and hospital capacity.
Infant mortality rate	Meaning: The number of deaths of infants under one year per thousand live births. Why it matters: It is a sensitive indicator of health care and living conditions. Example: Falling infant mortality accompanying improved sanitation and vaccination.
Demographic transition	Meaning: The shift from high birth and death rates to low ones as a country develops. Why it matters: It explains why population growth peaks partway through development. Example: Death rates falling first, producing rapid growth before birth rates follow.
Stage two of the demographic transition	Meaning: A stage where death rates fall but birth rates remain high. Why it matters: It produces the fastest population growth of any stage. Example: Improved sanitation reducing deaths while family sizes stay large.
Age structure diagram	Meaning: A graph showing the number of people in each age group by sex. Why it matters: Its shape predicts future growth even when current rates are known. Example: A broad-based pyramid indicating rapid growth ahead.
Doubling time	Meaning: The time a population takes to double at a given growth rate. Why it matters: It makes small differences in growth rate easier to grasp. Example: Dividing seventy by the percentage growth rate to get an approximate answer.
Ecological footprint	Meaning: The area of productive land and water needed to support a person or population. Why it matters: It compares consumption against what the planet can regenerate. Example: A high-consumption country requiring several times its own land area.
IPAT equation	Meaning: A framework describing impact as population times affluence times technology. Why it matters: It shows that consumption per person matters as much as headcount. Example: A small wealthy population having a larger impact than a large poor one.
Plate tectonics	Meaning: The theory that the Earth's outer shell is divided into moving plates. Why it matters: It explains the distribution of earthquakes, volcanoes and mountain ranges. Example: The Pacific Ring of Fire marking a boundary of converging plates.
Convergent boundary	Meaning: A boundary where plates move toward each other. Why it matters: It produces subduction zones, deep trenches and explosive volcanoes. Example: The Andes rising where an oceanic plate sinks beneath a continental one.
Subduction	Meaning: The sinking of one plate beneath another. Why it matters: It recycles crust and drives volcanic arcs above the descending plate. Example: Deep ocean trenches marking where a plate begins to descend.
Earthquake	Meaning: Ground shaking caused by a sudden release of stress in the crust. Why it matters: Building codes and land-use planning determine how much damage results. Example: The same magnitude event causing far more deaths where buildings are unreinforced.
Weathering	Meaning: The physical and chemical breakdown of rock at the Earth's surface. Why it matters: It is the first step in soil formation and releases mineral nutrients. Example: Freeze-thaw cycles splitting rock along existing cracks.
Soil permeability	Meaning: The rate at which water moves through soil. Why it matters: It determines runoff, infiltration and the risk of waterlogging. Example: Sandy soils draining rapidly while clay soils hold water at the surface.
Layers of the atmosphere	Meaning: The vertical divisions of the atmosphere by temperature behaviour. Why it matters: Each layer has distinct effects on weather, ozone and radiation. Example: The troposphere holding almost all weather and water vapour.
Ozone layer	Meaning: A region of the stratosphere with a high concentration of ozone. Why it matters: It shields the surface from harmful ultraviolet radiation. Example: Reduced ozone allowing more ultraviolet to reach high-latitude regions in spring.
Coriolis effect	Meaning: The apparent deflection of moving air and water caused by the Earth's rotation. Why it matters: It sets the direction of prevailing winds and ocean gyres. Example: Storms rotating in opposite directions in the two hemispheres.
Weather and climate	Meaning: Short-term atmospheric conditions and long-term average patterns. Why it matters: Confusing the two leads to misreading single events as trends. Example: A cold week occurring within a decade of rising average temperature.
Upwelling	Meaning: The rise of deep, nutrient-rich water toward the surface. Why it matters: It supports some of the world's most productive fisheries. Example: Coastal upwelling zones producing a large share of the global fish catch.
Watershed	Meaning: The land area that drains into a particular body of water. Why it matters: Everything that happens on that land affects the water quality downstream. Example: Fertiliser applied across a river basin reaching the estuary at its mouth.
Aquifer depletion	Meaning: The withdrawal of groundwater faster than it is recharged. Why it matters: It causes wells to fail and the land surface to subside. Example: Irrigated regions where the water table has fallen steadily for decades.
Surface water and groundwater	Meaning: Water in rivers and lakes and water stored beneath the ground. Why it matters: They are connected, so pumping one can reduce the other. Example: Groundwater pumping lowering the flow of a nearby stream in summer.
Floodplain	Meaning: The flat land beside a river that floods periodically. Why it matters: Building on it puts property in the path of predictable flooding. Example: Repeated flood damage to housing developments built on former floodplain.
Renewable resource	Meaning: A resource replenished on a human timescale. Why it matters: It remains available only if used no faster than it regenerates. Example: A fishery collapsing when catch rates exceed reproduction.
Industrial agriculture	Meaning: Large-scale farming using machinery, fertiliser and chemical inputs. Why it matters: It raises yields per hectare while increasing energy use and runoff. Example: Monoculture fields planted with a single crop variety across thousands of hectares.
Crop rotation	Meaning: Growing different crops in a field in successive seasons. Why it matters: It breaks pest cycles and restores soil nitrogen. Example: Following a cereal with a legume that fixes nitrogen for the next crop.
Soil salinisation	Meaning: The accumulation of salts in soil, usually from irrigation. Why it matters: It reduces yields and can make land unusable. Example: White salt crusts appearing on irrigated fields in a dry climate.
Pesticide	Meaning: A chemical used to kill organisms that damage crops. Why it matters: It raises short-term yields but harms non-target species and selects for resistance. Example: Beneficial insects killed alongside the pest species being targeted.
Biological pest control	Meaning: The use of natural enemies to suppress pests. Why it matters: It avoids chemical residues but can go wrong if the control agent spreads. Example: Ladybirds released to control aphids in a greenhouse.
Biomagnification	Meaning: The increase in the concentration of a chemical at successive trophic levels. Why it matters: Top predators receive the highest doses. Example: Thinning eggshells in fish-eating birds exposed to a persistent pesticide.
Contour ploughing	Meaning: Ploughing across a slope rather than up and down it. Why it matters: It slows runoff and reduces soil loss. Example: Curved field patterns following the contours of a hillside.
Overfishing	Meaning: Harvesting fish faster than the population can reproduce. Why it matters: It reduces catches over time and can collapse a fishery entirely. Example: The Atlantic cod fishery closing after stocks failed to recover.
Clear-cutting	Meaning: Removing all trees from an area at once. Why it matters: It is cheap but causes erosion, habitat loss and stream warming. Example: Sediment from a clear-cut hillside filling a salmon spawning stream.
Reforestation	Meaning: Replanting trees on land that was recently forested. Why it matters: It restores carbon storage and reduces erosion. Example: Replanting after a harvest to keep a forest in production.
Surface mining	Meaning: Extracting minerals by removing the overlying soil and rock. Why it matters: It is cheaper than underground mining but destroys the surface entirely. Example: Strip mining removing overburden in long parallel cuts.
Acid mine drainage	Meaning: Acidic water flowing from mines when sulphide minerals are exposed. Why it matters: It kills aquatic life and mobilises toxic metals. Example: Orange-stained streams below abandoned coal mines.
Urban sprawl	Meaning: Low-density expansion of a city into surrounding land. Why it matters: It consumes farmland, increases driving and raises infrastructure costs. Example: Housing developments spreading across former agricultural land at the city edge.
Smart growth	Meaning: Planning that concentrates development and preserves open space. Why it matters: It reduces sprawl and driving distances. Example: Mixed-use development near transit rather than separated single-use zones.
Ecological reserve	Meaning: An area set aside primarily to protect ecosystems and species. Why it matters: Reserve size and connectivity determine how much biodiversity survives. Example: Buffer zones surrounding a core protected area to reduce edge effects.
Ecotourism	Meaning: Travel to natural areas managed to minimise impact and support conservation. Why it matters: It gives local communities an economic reason to protect habitat. Example: Visitor fees funding ranger salaries in a wildlife reserve.
Fossil fuel	Meaning: A fuel formed from the buried remains of ancient organisms. Why it matters: Burning it releases carbon that had been stored underground for millions of years. Example: Coal, oil and natural gas supplying most of the world's commercial energy.
Natural gas	Meaning: A gaseous fossil fuel that is mostly methane. Why it matters: It emits less carbon dioxide per unit of energy than coal but leaks a potent greenhouse gas. Example: Gas plants used to balance variable renewable output on a grid.
Cogeneration	Meaning: Using the waste heat from electricity generation for heating. Why it matters: It raises the overall efficiency of a fuel far above electricity alone. Example: A factory using turbine exhaust heat for its industrial processes.
Passive solar design	Meaning: Designing a building to use sunlight for heating and lighting without machinery. Why it matters: It cuts energy demand for the entire life of the building. Example: South-facing windows with overhangs that admit winter sun and block summer sun.
Nuclear fission	Meaning: The splitting of heavy atomic nuclei to release energy. Why it matters: It generates large amounts of electricity with almost no carbon dioxide. Example: Uranium fuel rods sustaining a controlled chain reaction in a reactor core.
Half-life	Meaning: The time for half of a radioactive sample to decay. Why it matters: It determines how long waste must be isolated. Example: Isotopes with long half-lives dominating the long-term hazard of spent fuel.
Hydroelectric power	Meaning: Electricity generated from flowing or falling water. Why it matters: It provides reliable low-carbon power but alters river ecosystems. Example: Dams blocking fish migration unless passages are provided.
Solar photovoltaic	Meaning: Technology that converts sunlight directly into electricity. Why it matters: It has no emissions in operation and can be installed at any scale. Example: Rooftop panels supplying part of a household's electricity.
Wind power	Meaning: Electricity generated by turbines driven by moving air. Why it matters: It has low operating emissions and land beneath turbines stays usable. Example: Farmland continuing in cultivation around the base of wind turbines.
Geothermal energy	Meaning: Energy drawn from heat within the Earth. Why it matters: It provides steady output but is limited to areas with accessible heat. Example: Iceland using volcanic heat for both electricity and district heating.
Biomass energy	Meaning: Energy from burning or processing organic material. Why it matters: It can be near carbon neutral if the material is regrown. Example: Wood pellets burned in place of coal in a converted power station.
Hydrogen fuel	Meaning: A fuel that releases only water when burned or used in a fuel cell. Why it matters: Its emissions depend entirely on how the hydrogen was produced. Example: Hydrogen made from natural gas carrying the emissions of that process.
Pumped storage	Meaning: Storing energy by pumping water uphill and releasing it later. Why it matters: It is the largest-scale storage method currently in use. Example: Water pumped to an upper reservoir at night and released at peak demand.
Point source pollution	Meaning: Pollution entering the environment from a single identifiable place. Why it matters: It is easier to regulate because the source can be measured directly. Example: A discharge pipe from a factory into a river.
Primary pollutant	Meaning: A pollutant released directly into the air from a source. Why it matters: It can be reduced by controlling emissions at the source. Example: Carbon monoxide emitted from an engine exhaust.
Sulphur dioxide	Meaning: A gas released mainly by burning sulphur-containing fuels. Why it matters: It irritates airways and forms acid deposition downwind. Example: Emissions from coal combustion reduced by flue gas scrubbers.
Volatile organic compounds	Meaning: Carbon-based chemicals that evaporate easily at room temperature. Why it matters: They react with nitrogen oxides in sunlight to form ozone. Example: Solvents, paints and fuel vapours contributing to summer smog.
Industrial smog	Meaning: A grey haze of sulphur compounds and particulates from coal burning. Why it matters: It is associated with cold, damp conditions rather than sunlight. Example: Historic London smogs caused by domestic and industrial coal fires.
Acid deposition	Meaning: The fall of acidic compounds from the atmosphere as rain, snow or dry particles. Why it matters: It acidifies lakes and soils and damages forests and buildings. Example: Fish disappearing from lakes in regions with poorly buffered bedrock.
Indoor air pollution	Meaning: Contamination of the air inside buildings. Why it matters: People spend most of their time indoors, so exposure can exceed outdoor levels. Example: Cooking smoke in poorly ventilated homes.
Formaldehyde	Meaning: A volatile chemical released from some building materials and furnishings. Why it matters: It irritates eyes and airways and is classified as a carcinogen. Example: New pressed-wood furniture releasing it into a closed room.
Eutrophication	Meaning: Nutrient enrichment of a water body that triggers excessive algal growth. Why it matters: Decomposing algae consume oxygen and kill aquatic life. Example: Fertiliser runoff producing a low-oxygen dead zone in coastal waters.
Thermal pollution of water	Meaning: The raising of water temperature by human activity. Why it matters: Warmer water holds less oxygen and stresses cold-adapted species. Example: Cooling water discharged from a power plant into a river.
Primary wastewater treatment	Meaning: The physical removal of solids from sewage. Why it matters: Screening and settling remove large material and suspended solids. Example: Grit chambers and settling tanks at the start of a treatment plant.
Sanitary landfill	Meaning: An engineered site for burying solid waste. Why it matters: Liners and leachate collection are meant to protect groundwater. Example: Methane collected from a capped landfill and burned for energy.
Waste reduction hierarchy	Meaning: The ranking of waste strategies from most to least preferred. Why it matters: Reducing comes before reusing, which comes before recycling and disposal. Example: Redesigning packaging to use less material rather than recycling more of it.
Dose-response relationship	Meaning: The relationship between the amount of a substance and the effect observed. Why it matters: It underlies every risk assessment and exposure limit. Example: A curve rising steeply once a threshold exposure is exceeded.
Ozone depletion	Meaning: The thinning of the stratospheric ozone layer. Why it matters: It allows more ultraviolet radiation to reach the surface. Example: Chlorine from refrigerant gases catalysing ozone breakdown in polar spring.
Climate feedback	Meaning: A process that amplifies or dampens an initial climate change. Why it matters: Positive feedbacks make warming accelerate beyond the original cause. Example: Melting permafrost releasing methane that causes further warming.

Frequently asked

What is in each section of the deck?

Ecosystems and biodiversity has 55 cards, populations 40, earth systems and resources 50, land and water use 55, energy 45, and pollution and global change 55, for 300 in total. Every card carries section and subtopic tags, so you can drill only the energy unit or only the pollution unit.

Why are there no current statistics on the cards?

Because they go out of date faster than the deck does, and a wrong number is worse than no number. Emissions totals, energy shares and population figures all shift yearly. What does not shift is why a thermal inversion traps pollutants or why a dead zone forms, and that is what the cards carry.

Does it cover the maths on the exam?

It covers the concepts the calculations are built on, such as what a doubling time means or how energy is lost between trophic levels, but not the arithmetic itself. The exam's calculations are simple once the setup is right, and getting the setup right is what these cards support.

Can I import the whole deck on the free plan?

Yes. Importing a saved deck runs no new AI generation and spends no AI credits, so the free plan imports all 300 cards. You can study, edit and delete them afterwards.

Will importing it twice create duplicates?

No. Cards you already have are skipped and only cards added in a revision come through. Including re-imports after deleting it, one official deck can be imported three times per account.

Can I use it on the web and in the mobile app?

Yes. The deck is added to your account rather than to a device, so the same cards and the same progress are there on the web, on iOS and on Android.

Can I edit the cards after importing?

Yes. Imported cards are yours: you can edit both sides, delete cards you do not need, change tags, and move cards to another deck.