AP Environmental Science AP Exam Review: Vocab A-Z

1st Law of Thermodynamics (Energy)

The principle that energy may not be created or destroyed but is always conserved.

2nd Law of Thermodynamics (Energy)

A fundamental principle of energy that states that energy always tends to go from a more usable (higher equality) form to a less usable (lower quality) form. When we say that energy is converted to a less useful form we mean that entropy (a measure of the energy unavailable to do useful work) of the system has increased.

“A” Horizon

Horizon that is composed of both mineral and organic materials. The color is often light black to brown. Leaching, defined as the process of dissolving, washing, or draining earth materials by percolation of groundwater or other liquids, occurs in the A horizon and moves clay and other materials, such as iron and calcium, to the B horizon.

Abiotic

The nonliving components of an ecosystem.

Absorption

The ability of matter to absorb light energy shined on it. This light energy is converted into heat.

Accuracy

The degree of conformity of an indicated value to an accepted standard value, or ideal value.

Acid Deposition

A comprehensive term for the various ways acidic compounds precipitate from the atmosphere and deposit onto surfaces. It can include: 1.) wet deposition by means of acid rain, fog, and snow; and 2.) dry deposition of acidic particles (aerosols).

Acid Mine Drainage

Does not refer to an acid mine but to acidic water that drains from mining areas (mostly coal but also metal mines). The acidic water may enter surface water resources, causing environmental damage.

Acid Rain

Rain made artificially by pollutants, particularly oxides of sulfur and nitrogen. Natural rainwater is slightly acidic owing to the effect of carbon dioxide dissolved in the water.

Active Solar Energy

Solar radiation used by special equipment to provide space heating, hot water or electricity.

Acute Effects (Exposure)

Effects usually immediate, obvious, short-term responses to exposure to a hazard; they can be localized to one part of the body, or they can be systemic.

Aerobic

Living or occurring only in the presence of oxygen.

Aesthetic Justification (for the conservation of nature)

An argument for the conservation of nature on the grounds that nature is beautiful, and that beauty is important and valuable to people.

African Black Rhinoceros

The African black rhinoceros is on the endangered species list due to excessive poaching for their horns, which are mostly used in dagger handles as a symbol of wealth in many countries.

Age Structure (of a population)

Structure of a population divided into groups by age. Sometimes the groups represent the actual number of each age in the population or proportion of the population of each age.

Age Structure Diagram

A representation of the number of individuals in each age group in a population.

Albedo

Reflectivity; the fraction of radiation striking a surface that is reflected by that surface.

Aldehydes

Very reactive organic compounds that contribute to local and regional ozone production, and also act as the precursors of peroxyacetyl nitrates. Their major atmospheric fate is reaction with hydroxyl radicals or photolysis.

Alveoli

Microscopic air sacs in the lungs at the end of bronchioles where gases are exchanged.

Anaerobic

Living, active or occurring in the absence of oxygen. Without oxygen.

Anthracite Coal

A shiny black, hard coal that burns slowly and gives off intense heat, highest heat content among the ranks of coal.

Anthropogenic

Produced by human activity.

Aquaculture

Production of food from aquatic habitats.

Aqueduct

A constructed system of canals, channels and/or pipelines to move water from one location to another.

Area Source (Non-point)

A source of pollution that cannot always be traced to an exact point of entry.

Artesian Well

A well in which the water comes from a confined aquifer and is under pressure.

Aswan High Dam

One of the world's largest dams on the Nile River in southern Egypt.

Atmosphere

The layer of gases surrounding Earth.

Autotroph

An organism that produces its own food from inorganic compounds and a source of energy. There are photoautotrophs (photosynthetic plants) and chemical autotrophs.

“B” Horizon

Horizon that is enriched in clay, iron oxides, silica, carbonate, or other material leached from overlying horizons. This horizon is known as the zone of accumulation.

Baby Boom

The jump in birthrates in the years after World War Two. “Baby boomers” are the generation born between 1945 and about 1960. In this period, more than 65 million children were born. They grew up in a generally prosperous period in American life, but also experienced as teenagers the uncertainties and conflicts of the 1950s and 1960s.

Background Extinction Rate

The continuous, low-level extinction of species that has occurred throughout much of history.

Background Radiation

Radiation that comes from natural sources and is always present in the environment. This includes solar and cosmic radiation as well as radioactive elements in the ground, building materials, and the human body. Average annual dose of background radiation for an American is about 360 milligrams.

Baghouse Filter

Large fabric bag, usually made of glass fibers, used to eliminate intermediate and large (greater than 20 µm in diameter) particles. This device operates like the bag of an electric vacuum cleaner, except the particles get trapped on the outside of the bag.

Bauxite

The raw material mined from the earth we use to make aluminum.

Benthos

The bottom of a sea or lake.

Bioaccumulation

A process by which chemical substances are ingested and retained by organisms, either from the environment directly or through consumption of food containing the substances.

Biodiesel

An environmentally safe, low polluting fuel for most diesel internal combustion and turbine engines. Can be mixed with petroleum diesel fuel and stored anywhere petroleum is stored. Made from fresh or waste vegetable oils (triglycerides) that are a renewable energy source. Both commercially and privately made around the world.

Biodiversity

The number and variety of living organisms; includes genetic diversity, species diversity, and ecological diversity.

Biogeography

The large-scale geographic pattern in the distribution of species, and the causes and history of this distribution.

Biological Control

A set of methods to control pest organisms by using natural ecological interactions, including predation, parasitism, and competition. Part of the integrated pest management (IPM).

Biological Evolution

The change in inherited characteristics of a population from generation to generation, which can result in new species.

Biomagnification

Also called biological concentration. The tendency for some substances to concentrate with each trophic level. Organisms preferentially store certain chemicals and excrete others. When this occurs consistently among organisms, the stored chemicals increase as a percentage of the body weights as the material is transferred along a food chain or trophic level. For example, the concentration of DDT is greater in herbivores than in plants and greater in plants in the nonliving environment.

Biomass

The amount of living material or the amount of organic material contained in living organisms, both as live and dead material, as in the leaves (live) and stem wood (dead) of trees.

Biomass Energy

A new name for the oldest fuel used by humans, that is also called Biomass Fuel. Biomass Energy is organic matter, such as plant material and animal waste, which can be used as a fuel.

Biome

A kind of ecosystem. The rain forest is an example of a biome; rain forests occur in many parts of the world but are not all connected with each other.

Bioremediation

A method of treating groundwater pollution problems that utilizes microorganisms in the ground to consume or break down pollutants.

Biota

A general term for all the organism of all species living in an area or region up to and including the biosphere, as in “the biota of the Mojave Desert” or “the biota in that aquarium.”

Biotic

The living components of an ecosystem.

Birth Rate

The rate at which births occur in a population, measured either as the number of individuals born per unit of time compared with the population.

Bituminous Coal

A dense, black, soft coal, often with well-defined bands of bright and dull material. The most common coal, with moisture content usually less than 20 percent. Used for generating electricity, making coke, and space heating.

Board Feet

The most common measure used to describe log and lumber volume. A board foot is a board measuring 12 x 12 x 1 thick.

BOD (Biological Oxygen Demand)

A measure of the amount of oxygen necessary to decompose organic material in a unit volume of water. As the amount of organic waste in water increases, more oxygen is used, resulting in a higher BOD.

Body Burden

The amount of concentration of a toxic chemical, especially radionuclides, in an individual.

Bog

A bog is a wetland type that accumulates acidic peat, a deposit of dead plant material.

Breeder Reactor

A nuclear reactor that manufactures more fissionable isotopes than it consumes. Breeder reactors use the widely available, non-fissionable uranium isotope U-238, together with small amounts of fissionable U-235, to produce a fissionable isotope of plutonium, Pu-239.

British Thermal Unit (BTU)

A unit used to measure quantity of heat, defined as the quantity of energy necessary to raise the temperature of 1 lb. of water 1° Fahrenheit.

Broad Spectrum Pesticide

Pesticides that kill a wide variety of organisms. Arsenic, one of the first elements used as a pesticide, is toxic to many life-forms, including people.

Bronchiole

Small airway (subdivision of the bronchus) that leads to areas of the lung and absorbs oxygen from the air.

Brownfield

An abandoned or underutilized property that is not being redeveloped because of fears that it may be contaminated with hazardous substances.

Buffer

Materials (chemicals) that have the ability to neutralize acids. Examples include the calcium carbonate that is present in many soils and rocks. These materials may lessen potential adverse effects of acid rain.

“C” Horizon

Horizon is composed of partially altered (weathered) parent material; the material could be rock or be alluvial in nature, such as river gravels in other environments. This horizon may be stained red with iron oxides.

California Condor

A large, endangered North American bird with the largest wingspan in the western Hemisphere.

California Water Project

The California State Water Project (SWP) is one of the largest water development projects in the world. The project was designed to transfer 5.4 billion m3 from the northern Sacramento River basin to areas of need in central and southern regions of the state. Also, it is the key means for the State to re–route water among critical regions in times of severe shortages.

Carbon Cycle

Combined biochemical cycles of carbon, oxygen, and hydrogen. Carbon combines with and is chemically and biologically linked with the cycles of oxygen and hydrogen that form the major compounds of life.

Carcinogens

Any material that is known to produce cancer in humans or other animals.

Carnivore

Organisms that feed on other live organisms; usually applied to animals that eat other animals; a meat eater.

Carrying Capacity

The maximum abundance of a population or species that can be maintained by a habitat or ecosystem without degrading the ability of that habitat or ecosystem to maintain that abundance in the future.

Cash Crop

Crops grown to be sold in a market, often supplant food crops that can feed local populations.

Catalytic Converter

An air pollution abatement device that removes pollutants from motor vehicle exhaust, either by oxidizing them into carbon dioxide and water or reducing them to nitrogen.

Chain Reaction

A self-sustaining series of reactions, in particular those of nuclear fission in which the particles released by one nucleus trigger the fission of at least as many further nuclei.

Channelization

An engineering technique that consists of straightening, deepening, widening, clearing, or lining existing stream channels. The purpose is to control floods, improve drainage, control erosion, or improve navigation. It is a very controversial practice that may have significant environmental impacts.

Chemosynthesis

Synthesis of organic compounds by energy derived from chemical reactions.

Chernobyl, Ukraine

In April 1986 there was an explosive leak, caused by overheating, from a non- pressurized boiling-water reactor, one of the largest in Europe. The resulting clouds of radioactive material spread as far as the UK. Thirty-one people were killed in the explosion, and thousands of square kilometers of land were contaminated by fallout. By June 1992, seven times as many children in the Ukraine and Belarus were contracting thyroid cancer as before the accident, and the incidence of leukemia was rising; it was estimated that more than 6,000 people had died as a result of the accident, and that the death toll in the Ukraine alone would eventually reach 40,000.

Chlorofluorocarbons (CFCs)

Highly stable compounds that have been or are being used in spray cans as aerosol propellants and in refrigeration units (the gas that is compressed and expanded in a cooling unit). Emissions of chlorofluorocarbons have been associated with potential global warming and stratospheric ozone depletion.

Cholera

An acute intestinal infection caused by ingestion of contaminated water or food.

Chronic Effects (Exposure)

Long-lasting results of exposure to a toxin; can be a permanent change caused by a single, acute exposure or a continuous, low-level exposure.

Cilia

Short hair-like appendages found on the surfaces of some types of cells and organisms; used for either propelling trapped material out of the body or for locomotion.

City Planning

Conscious design of the growth and development of an urban area.

Clear-cutting

In timber harvesting, the practice of cutting all trees in a stand at the same time.

Climate

The representative or characteristic conditions of the atmosphere at particular places on Earth. Climate refers to the average or expected conditions over long periods; weather refers to the particular conditions at one time in one place.

Climax State

The final stage of ecological succession and therefore an ecological community that continues to reproduce itself over time, or a stage in ecological succession during which an ecological community achieves the greatest biomass or diversity. (The first definition is the classical definition.)

Closed Systems

A type of system in which there are definite boundaries to factors such as mass and energy such that exchange of these factors with other systems does not occur.

Colorado River

The Colorado River is a river in the southwestern United States and northwestern Mexico, approximately 1,450 mi. (2,333 km) long, draining a part of the arid regions on the western slope of the Rocky Mountains. The natural course of the river flows into the Gulf of California, but the heavy use of the river as a fresh water source has desiccated the lower course of the river in Mexico such that it no longer reaches the sea.

Commensalism

A relationship between two kinds of organisms in which one benefits from the relationship and the other is neither helped nor hurt.

Commercial Forestry

In order to retain biodiversity in commercial forest, they must be managed in ways that simulate disturbances that take place in old-growth forests, such as forest fires and storms. Over time, some of the structural characteristics of old-growth forests, such as old trees, deadwood and deciduous trees, can also be added.

Commons

Land that belongs to the public, not to individuals. Historically a part of old English and New England towns where all the farmers could graze their cattle.

Competition

The situation that exists when different individuals, populations, or species compete for the same resources and the presence of one has a detrimental effect on the other. Sheep and cows eating grass in the same field are competitors.

Competitive Exclusion Principle

The idea that two populations of different species with exactly the same requirements cannot persist indefinitely in the same habitat – one will always win out and the other will become extinct. Which one wins depends on the exact environmental conditions. Referred to as a principle, the idea has some basis in observation and experimentation.

Composting

Biochemical process in which organic materials, such as lawn clippings and kitchen scraps, are decomposed to a rich, soil-like material.

Confined Aquifer

An aquifer that is bound above and below by dense layers of rock and contains water under pressure.

Contour Farming (Plowing)

Plowing land along topographic contours, perpendicular to the slope, as much in the horizontal plane as possible, thereby decreasing the erosion rate.

Control Group

The specimen that is used as an example in the experiment; a standard against which other conditions can be compared in a scientific experiment.

Control Rod

A device in the core of a reactor which absorbs neutrons, and is used to control the rate of fission and to stop the chain reaction.

Controlled Burning

Using prescribed fire to reduce the risk from wildfires, control tree diseases, increase food and habitat for wildlife, and manage forests for greater production of desirable tree species.

Controlled Experiment

A controlled experiment is designed to test the effects of independent variables on a dependent variable by changing only one independent variable at a time. For each variable tested, there are two set-ups (an experiment and a control) that are identical except for the independent variable being tested. Any difference in the outcome (dependent variable) between the experiment and the control can then be attributed to the effects of the independent variable tested.

Convergent Evolution

The process by which species evolve in different places or different times and, although they have different genetic heritages, develop similar external forms and structures as a result of adaptation to similar environments. The similarity in the shapes of sharks and porpoises is an example of convergent evolution.

Convergent Plate Boundary

Boundary between two lithosphere plates in which one plate descends below the other (subduction).

Core

The innermost layer of the Earth, made up of mostly of iron and nickel. The core is divided into a liquid outer core and a solid inner core. The core is the densest of the Earth’s layers.

Cosmopolitan Species

A species with a broad distribution, occurring whenever in the world the environment is appropriate.