AP Environmental Science Comprehensive Vocabulary Review

A comprehensive vocabulary review of core ecological, geological, atmospheric, agricultural, pollution, and global health concepts.

Symbiosis

A close, long-term interaction between organisms of different species; the interaction may benefit, harm, or have little effect on either organism.

Mutualism

A symbiotic relationship in which both species benefit.

Commensalism

A symbiotic relationship in which one species benefits while the other is neither helped nor harmed.

Parasitism

A symbiotic relationship in which a parasite benefits by living on or in a host, which is harmed.

Resource partitioning

The division of limited resources among species, often by using different places, food sources, or times of activity.

Species interaction

An effect that members of one species have on members of another, such as competition or cooperation.

Competition

An interaction in which organisms seek the same limited resource, such as food, space, or light.

Niche

A species' role in its ecosystem, including how it uses resources and interacts with other organisms.

Host

An organism that provides a parasite with food or a place to live.

Parasite

An organism that gains resources from a host while causing the host harm.

Adaptation

An inherited feature or behavior that helps an organism survive or reproduce in its environment.

Coevolution

Evolutionary change in one species that occurs in response to changes in another interacting species.

Interspecific

Occurring between different species.

Limiting resource

A resource in short supply that restricts the growth, survival, or reproduction of organisms.

Intraspecific

Occurring within a single species or between individuals of the same species.

Terrestrial

Related to land environments or living on land.

Aquatic

Related to water environments or living in water.

Marine

Related to salt water, especially oceans and seas.

Temperate

Having a moderate climate, often with distinct seasons and neither extreme heat nor extreme cold for most of the year.

Tropical

Related to regions near the equator that are generally warm throughout the year.

Latitude

The geographic coordinate that measures the distance north or south of the Earth's equator, calculated in degrees.

Altitude

The vertical distance or height of an object or point relative to sea level or ground level.

Climate

The long-term average of weather patterns in a specific region.

Marsh

A type of wetland dominated by herbaceous (non-woody) plants like grasses, reeds, and sedges, often found at the edges of lakes and streams.

Estuary

A partially enclosed coastal body of brackish water where one or more rivers or streams meet and mix with the open sea.

Salinity

The concentration of dissolved salts in a body of water.

Turbidity

The measure of water cloudiness or murkiness caused by suspended particles like sediment, algae, or organic matter.

Dissolved Oxygen

The amount of free, non-compound oxygen gas available in water, which is critical for the survival of aquatic organisms.

Carbon Source

Any process, activity, or mechanism that releases more carbon dioxide into the atmosphere than it absorbs (e.g., burning fossil fuels, volcanic eruptions).

Carbon Sink

A natural or artificial reservoir that absorbs and stores more carbon from the atmosphere than it releases (e.g., oceans, forests).

Reservoir

A component of the biosphere that stores a specific substance—such as carbon or water—for a period of time.

Photosynthesis

The chemical process used by plants, algae, and some bacteria to convert light energy, carbon dioxide, and water into glucose and oxygen.

Cellular Respiration

The biochemical process by which cells break down glucose and oxygen to produce energy (ATP), releasing carbon dioxide and water as byproducts.

Decomposition

The organic process where decomposers (like bacteria and fungi) break down dead organisms and waste material, releasing nutrients and carbon back into the ecosystem.

Atmospheric Carbon

The carbon present in the Earth's atmosphere, primarily in the form of greenhouse gases like carbon dioxide ($CO_2$) and methane ($CH_4$).

Limiting Factor

Any resource or environmental condition that limits the growth, abundance, or distribution of an organism or a population within an ecosystem.

Primary Productivity

The rate at which solar energy is converted into organic compounds by producers through photosynthesis over a given period of time.

Respiration Loss

The amount of energy or biomass that producers use for their own cellular respiration, which is lost to the environment as heat.

10% Rule of Energy Transfer

An ecological principle stating that only about $10\%$ of the energy at one trophic level is passed on to the next level, while the rest is lost as heat or waste.

1st Law of Thermodynamics

The law of conservation of energy, which states that energy cannot be created or destroyed, only transformed from one form to another.

2nd Law of Thermodynamics

The law stating that every energy transfer increases the entropy (disorder) of the universe, meaning energy is always lost as low-quality heat during conversions.

Trophic Level

The specific position or step an organism occupies in a food chain or ecological pyramid (e.g., producer, primary consumer).

Producer

An organism that makes its own food using inorganic molecules and an external energy source, such as sunlight.

Consumer

An organism that obtains energy by feeding on other organisms or organic matter.

Autotroph

An organism that is capable of synthesizing its own food from simple inorganic substances; synonymous with producer.

Heterotroph

An organism that cannot produce its own food and must consume other organic carbon sources for energy; synonymous with consumer.

Biogeochemical Cycle

The pathway by which a chemical substance moves through both the biotic (living) and abiotic (non-living) compartments of Earth (e.g., carbon, nitrogen, or phosphorus cycles).

Hydrologic

Relating to hydrology, the scientific study of the properties, distribution, and movement of water across the Earth and its atmosphere.

Groundwater

Water that is stored underground in the spaces between soil particles and within the fractures of rock formations (aquifers).

Surface Water

Water that collects on the ground or in a stream, river, lake, wetland, or ocean.

Positive Feedback Loop

A system response in which the output of a process amplifies or accelerates the original change, driving the system further away from its equilibrium (e.g., melting ice reducing albedo, causing more warming).

Negative Feedback Loop

A system response that counteracts or dampens the original change, helping to maintain stability or return the system to equilibrium (e.g., predator-prey population cycles).

Anthropogenic

Anything caused or produced by human activity, particularly relating to environmental pollution or climate impact.

Food Chain

A linear sequence of organisms through which nutrients and energy pass as one organism eats another.

Food Web

A complex, interconnected network of multiple food chains that shows the feeding relationships among all organisms in an entire ecosystem.

Biodiversity

The variety and variability of life on Earth, encompassing all levels of biological organization from genes to ecosystems.

Genetic Diversity

The total number of genetic characteristics and variations within a single species or population, which helps them adapt to changing environments.

Species Diversity

A measure of biodiversity that takes into account both the number of different species present and their relative abundance within a specific community.

Ecosystem Diversity

The variety of different habitats, biological communities, and ecological processes across a geographic area.

Population Bottleneck

A sharp, temporary reduction in the size of a population due to an environmental event or human activity, which severely reduces genetic diversity.

Species Richness

The total number of unique species present in a specific ecological community, landscape, or region.

Generalist Species

A species capable of thriving in a wide variety of environmental conditions and making use of many different resources (e.g., raccoons, rats).

Specialist Species

A species that can only thrive in a narrow range of environmental conditions or has a highly specific diet (e.g., giant pandas, koalas).

Ecosystem Services

The varied benefits that humans freely gain from the natural environment and from properly functioning ecosystems.

Provisioning Services

The material goods or products obtained directly from ecosystems, such as food, fresh water, timber, and medicinal resources.

Regulating Services

The benefits obtained from the regulation of ecosystem processes, such as climate regulation, water purification, flood control, and pollination.

Cultural Services

The non-material benefits people gain from ecosystems, including spiritual enrichment, recreation, aesthetic values, and tourism.

Supporting Services

The fundamental natural processes underlying all other ecosystem services, such as soil formation, nutrient cycling, and primary production.

Island Biogeography

A field of ecology that examines the factors affecting species richness and diversity on isolated communities, stating that larger islands and islands closer to the mainland have higher biodiversity.

Invasive Species

A non-native organism whose introduction causes economic or environmental harm to an ecosystem where it does not naturally belong.

Ecological Tolerance

The range of abiotic conditions (such as temperature, salinity, or sunlight) within which an organism or species can survive, grow, and reproduce.

Migration

The seasonal, predictable movement of a population from one geographic region to another, typically driven by changes in food availability, climate, or mating needs.

Sea-Level Rise

The increase in the average height of the world's oceans, primarily driven by thermal expansion from warming water and the melting of land-based ice.

Glacial Retreat

The shrinking or melting backward of glaciers when the rate of ablation (melting and evaporation) exceeds the accumulation of new snow and ice.

Periodic

Events or natural disruptions that occur at regular, predictable intervals (e.g., tides, seasons, or daily light cycles).

Episodic

Events or natural disruptions that occur irregularly or occasionally at distinct, unpredictable intervals (e.g., El Niño cycles, volcanic eruptions, or major earthquakes).

Random

Events or natural disruptions that occur with no regular pattern, predictability, or definite interval (e.g., a localized lightning strike or a random meteor impact).

Ecological Succession

The gradual and predictable process of change in the species composition and structure of a biological community over time, often following a disturbance.

Primary Succession

Ecological succession that begins in an entirely lifeless area with no pre-existing soil or sediment, such as bare rock exposed by a retreating glacier or cooled lava.

Secondary Succession

Ecological succession that occurs in an area where a disturbance has cleared an existing community, but the soil remains intact (e.g., following a wildfire, hurricane, or clear-cutting).

Keystone Species

A species that has an exceptionally large effect on its ecosystem relative to its abundance, driving the overall structure and stability of the entire community.

Pioneer Species

The first hardy organisms to colonize a bare or disturbed area, playing a crucial role in breaking down substrate or accumulating organic matter to form the initial layers of soil.

Biomass

The total mass or weight of living biological organisms within a given area or ecosystem at a specific time.

K-selected Species

Species that tend to reproduce slowly, have few offspring, and invest significant parental care into ensuring individual survival; their populations usually hover around the ecosystem's carrying capacity ($K$).

r-selected Species

Species that reproduce rapidly, have a high growth rate ($r$), and produce a massive number of offspring with little to no parental care, leading to frequent population booms and busts.

Biotic Potential

The maximum reproductive capacity of a population under ideal environmental conditions (unlimited resources, no disease, and no predation).

Survivorship Curve

A graphical representation showing the number or proportion of individuals surviving at each age for a given species.

Type 1 Survivorship Curve

A pattern showing high survival rates throughout most of the lifespan, with individuals dying in large numbers at old age; typical of K-selected species like humans or elephants.

Type 2 Survivorship Curve

A pattern showing a relatively constant mortality and survival rate throughout the entire lifespan, meaning death is equally likely at any age; typical of organisms like songbirds, rodents, and some reptiles.

Type 3 Survivorship Curve

A pattern showing very low survivorship early in life, with steep mortality among offspring, but high survival rates for the few individuals that manage to reach adulthood; typical of r-selected species like sea turtles, frogs, or dandelions.

Population Overshoot

Occurs when a population exceeds the carrying capacity of its environment, leading to a temporary suspension of natural limits.

Carrying Capacity

The maximum number of individuals of a given species that an environment can sustainably support long-term without degrading its resource base.

Population Dieback

A sudden, sharp decline in a population's size that happens when a population overshoots its carrying capacity and suffers from severe resource shortages.

Resource Depletion

The act of consuming natural resources faster than they can naturally replenish or recover.

Fecundity

The actual reproductive rate or physical capability of an individual or population to produce offspring.

Mortality

The rate of death within a population, typically measured as deaths per 1,000 individuals per year.

Density-Dependent Limiting Factors

Environmental factors whose influence on population growth changes depending on the density of the population (e.g., disease, competition for food, predation).

Density-Independent Limiting Factors

Environmental factors that affect a population's size regardless of its density (e.g., wildfires, floods, hurricanes, severe droughts).

Age Structure Diagram

A graphical illustration showing the distribution of various age groups (usually split by sex) within a population, typically shaped like a pyramid for growing populations.

Total Fertility Rate (TFR)

The average number of children a woman will have during her lifetime within a specific population.