AP Environmental Science Study Guide


Abyssal Zone
The portion of the ocean floor where light does not penetrate and where temperatures are cold and pressures intense.

Age Structure Graph
proportion of people in different age groups in a population

A small, very toxic molecule (NH3) produced by nitrogen fixation or as a metabolic waste product of protein and nucleic acid metabolism.

Layers of air surrounding the earth.

Organisms that are able to make their own food

Background Extinction
Normal extinction of various species as a result of changes in local environmental conditions.

Bathyal Zone
the steep descent of the seabed from the continental shelf to the abyssal zone

Benthic Zone
bottom of an aquatic ecosystem; consists of sand and sediment and supports its own community of organisms

organisms (plants and animals) that live at or near the bottom of a sea

Biogeochemical Cycles
carbon, nitrogen, sulfur, water cycles, process in which elements, chemical compounds, and other forms of matter are passed from one organism to another and from one part of the biosphere to another

Plant materials and animal waste used especially as a source of fuel.

a broad, regional type of ecosystem characterized by distinctive climate and soil conditions and a distinctive kind of biological community adapted to those conditions.

Consists of all life on Earth and all parts of the Earth in which life exists, including land, water, and the atmosphere.


Biotic Potential
Maximum rate at which the population of a given species can increase when there are no limits on its rate of growth.

Birth Rate
the number of births in a population in a certain amount of time

Broadleaf Evergreen
Plants that keep most of their broad leaves year-round. Examples are the trees found in the canopies of tropical rain forests.

Consumers that eat only animals

Carrying Capacity
Largest number of individuals of a population that a environment can support

Overall weather in an area over a long period of time

A relationship between two organisms of different species where one benefits and the other is neither harmed nor benefited

Competitive Exclusion Principal
Ecological rule that states that no two species can occupy the same exact niche in the same habitat at the same time

Coniferous Evergreen
Cone-bearing plants (such as spruces, pines, and firs) that keep some of their narrow, pointed leaves (needles) all year.

Convergent Boundary
A plate boundary where two plates move toward each other

Cultural Carrying Capacity
the maximum number of people who could live in reasonable freedom and comfort indefinitely, without decreasing the ability of the earth to sustain future generations.

Cultural Eutrophication
an increase in biological productivity and ecosystem succession caused by human activities

Mass movements of surface water produced by prevailing winds blowing over the oceans.

Death Rate
The number of deaths in a population in a certain amount of time

Bacteria that break down nutrients in dead matter into simpler substances

Demographic Transition
Change in a population from high birth and death rates to low birth and death rates

Degradation of land, especially in semiarid areas, primarily because of human actions like excessive crop planting, animal grazing, and tree cutting.

organism that feeds on plant and animal remains and other dead matter

A sudden population decline; also called a population crash

Divergent Boundary
A plate boundary where two plates move away from each other

Ecological Efficency
percent of biomass in one trophic levelthat is converted into biomass in the next highest level

Scientific study of interactions among organisms and between organisms and their environment


El Nino
A periodic change in the pattern of ocean currents and water temperature in the mid-pacific region

Migration from a location

Endangered Species
A species whose numbers are so small that the species is at risk of extinction

Endemic Species
species that are native to and found only within a limited area

Environmental Resistance
All the limiting factors that tend to reduce population growth rates and set the maximum allowable population size or carrying capacity of an ecosystem

Euphotic Zone
Upper layer of a body of water through which sunlight can penetrate and support photosynthesis.

Eutrophic Lake
Lake with a large or excessive supply of plant nutrients, mostly nitrates and phosphates.

A process by which nutrients, particularly phosphorus and nitrogen, become highly concentrated in a body of water, leading to increased growth of organisms such as algae or cyanobacteria.

Change in a kind of organism over time; process by which modern organisms have descended from ancient organisms.

Exotic Species
organisms that are not native to a particular area

Exponential Growth
Growth pattern in which the individuals in a population reproduce at a constant rate

a severe shortage of food (as through crop failure) resulting in violent hunger and starvation and death

First Law of Thermodynamics
Heat is a form of energy which can be neither created nor destroyed but can be changed in form

Foundation Species
Species that plays a major role in shaping communities by creating and enhancing a habitat that benefits other species.

Gausse’s Principle

Generalist Species
Species with a broad ecological niche. They can live in many different places, eat a variety of foods, and tolerate a wide range of environmental conditions. Examples are flies, cockroaches, mice, rats, and human beings. Compare specialist species.

Genetic Drift
A change in the allele frequency of a population as a result of chance events rather than natural selection.

Genetic Engineering
Process of making changes in the DNA code of living organisms

Geographic Isolation
form of reproductive isolation in which two populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water

Global Warming
An increase in the average temperature of the earth’s atmosphere (especially a sustained increase that causes climatic changes)

Greenhouse Effect
Natural situation in which heat is retained in Earth’s atmosphere by carbon dioxide, methane, water vapor, and other gases

Place where an organism lives

An organism that eats only plants.

An organism that obtains organic food molecules by eating other organisms or their by-products.

All the water at and near the surface of the earth, 97% of which is in oceans

intrusive or extrusive rock that is produced when melted rock from inside Earth cools and hardens

Migration to a new location

Indicator Species
Species that serve as early warnings that a community or ecosystem is being degraded.

Infant Mortality Rate
the death rate during the first year of life

water on the ground surface enters the soil

Interspecific Competition
Competition between members of different species

Intraspecific Competition
Competition among members of the same species

Keystone Species
A species that influences the survival of many other species in an ecosystem

reproduce late in life; few offspring; care for offspring

La Nina
A cooling of the ocean surface off the western coast of South America, occurring periodically every 4 to 12 years and affecting Pacific and other weather patterns.

Law of Conservation of Matter
Matter is neither created nor destroyed

Small raised areas in the bark of stems and roots that enable gas exchange between living cells and the outside air.

Life Expectancy
A figure indicating how long, on average, a person may be expected to live. Normally expressed in the context of a particular state.

Limnetic Zone
area in a freshwater habitat away from the shore but still close to the surface

Linear Growth
Expansion that increases by the same amount during each time interval.

A rigid layer made up of the uppermost part of the mantle and the crust.

Littoral Zone
a shallow zone in a freshwater habitat where light reaches the bottom and nurtures plants

Logistic Growth
Growth pattern in which a population’s growth rate slows or stops following a period of exponential growth

flowing water

Mass extenction
when many species become extinct in one period of time

Lakes with moderate amounts of nutrients and phytoplankton productivity intermediate to oligotrophic and eutrophic systems.

A type of rock that forms from an existing rock that is changed by heat, pressure, or chemical reactions.

Ability of an animal to look like another more harmful animal

(genetics) any event that changes genetic structure

A relationship between two species in which both species benefit

Native Species
Species that normally live and thrive in a particular ecosystem

Natural Selection
A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.

Negative Feedback Loop
A feedback loop that causes a system to change in the opposite direction from which it is moving

All organisms that swim actively in open water, independent of currents

Net Primary Producer
the amount of energy (per unit of time) that producers fix by photosynthesisor other means, minus the amount they use in cellular respiration

Full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions

Special compounds containing nitrogen and oxygen

Form in which nitrogen may be found in the soil. Chemical formula NO2

Nitrogen Fixation
Process of converting nitrogen gas into ammonia

Non-renewable Resources
a resource that cannot be reused or replaced easily (ex. gems, iron, copper, fossil fuels)

a condition of a lake or other body of water characterized by low nutrients, low productivity, and high oxygen levels in the water column.

An organism that eats both plants and animals.

A relationship between two organisms of different species where one benefits and the other is harmed

Ability of rock or soil to allow water to flow through it

A process by which plants make their own food

Microscopic, free-floating, autotrophic organisms that function as producers in aquatic ecosystems

Plate Tectonics
The theory that pieces of Earth’s lithosphere are in constant motion, driven by convection currents in the mantle.

Addition of more waste than a resource can accommodate.

Population Growth Rate
rate of natural increase

The percentage of the total volume of a rock or sediment that consists of open spaces.

Positve Feedback Loop
only a few examples in human body, the stimulus doesn’t produce an opposite and counteracting effect

Primary Secession
succesion that begins at a place where there had been no life before

Make their own food from compounds obtained from their environment

Profundal Zone
zone in a freshwater habitat that is below the limits of effective light penetration

Rain Shadow Effect
Precipitation falls on the windward side of a mountain range, resulting in lush vegetation & a warm, moist climate on one side, but a desert area on the leeward side.

Renewable Resource
Any natural resource (as wood or solar energy) that can be replenished naturally with the passage of time

Replacement-Level Fertility
the number of children a couple must have to replace themselves (2.1 developed, 2.7 developing)

Reproductive Isolation
Separation of species or populations so that they cannot interbreed and produce fertile offspring

strength; ability to withstand

A substance in the environment that is useful to people, is economically and technologically feasible to access, and is socially acceptable to use.

Resource Partitioning
The division of environmental resources by coexisting species such that the niche of each species differs by one or more significant factors from the niches of all coexisting species

A symbiotic bacterium that lives in the nodules on roots of specific legumes and that incorporates nitrogen gas from the air into a form of nitrogen the plant requires

Species characterized by rapid growth, high fertility, short lifespan, and exponential population growth

A process in which mineral salts accumulate in the soil, killing plants; occurs when soils in dry climates are irrigated profusely

Second law of Thermodynamics
thermal energy that flows from a warmer material to a cooler material

A type of rock that forms when particles from other rocks or the remains of plants and animals are pressed and cemented together

Soil Erosion
Movement of soil components, especially topsoil, from one place to another, usually by wind, flowing water, or both. This natural process can be greatly accelerated by human activities that remove vegetation from soil.

Soil Horizon
The layer of soil that differs in color and texture from the layers above or below it.

Soil Profile
All the vertical layers or horizons that make up a soil in a particular place

Specialist Species
Species with a narrow ecological niche. They may be able to live in only one type of habitat, tolerate only a narrow range of climatic and other environmental conditions, or use only one type or a few types of food.

Formation of new species

Species Eveness
the relative abundance of each species

Species Richness
The number of different species in a community

Subduction Zone
The region where oceanic plates sink down into the asthenosphere.

full of juice or sap. thick, fleshy, waterstoring leaves. highly interesting or enjoyable. (In the desert, most of the leaves are very succulent because water is scarce.)

Survival of the Fittest
Process by which individuals that are better suited to their environment survive and reproduce most successfully; also called natural selection

Development that meets the needs of the present without compromising the ability of future generations to meet their own needs.

Synergistic Interaction
Interaction of two or more factors or processes so that the combined effect is greater than the sum of their separate effects

Tipping Point
the time at which a change or an effect cannot be stopped

Total Fertility Rate
The number of children born to an average woman in a population during her entire reproductive life

Tragedy of the Commons
A parable that illustrates why common resources are used more than is desirable from the standpoint of society as a whole- Garrett Hardin

Transform Boundary
A plate boundary where two plates move past each other in opposite directions

Trophic Levels
The hierarchical levels of the food chain through which energy flows from primary producers to primary consumers, secondary consumers and so on.

much smaller plankton, photosynthetic bacteria may be responsible for 70% of the primary productivity near the ocean surface.

The movement of deep, cold, and nutrient-rich water to the surface

Conditions in the atmosphere closest to Earth

Zero Population Growth
A decline of the total fertility rate to the point where the natural increase rate equals zero.

microscopic animals that swim or drift near the surface of aquatic environments

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