AP Environmental Science Key Terms

Food web

A food web is many food chains linked together to show a more accurate model of all possible feeding relationships of organisms in an ecosystem.

Gross Primary Productivity (GPP)

All available energy; rate that producers convert solar energy into chemical energy

Biomagnification

Biomagnification is the process whereby the tissue concentrations of a contaminant increase as it passes up the food chain through two or more trophic levels.

Tertiary Consumers

Carnivores that eat secondary producers; meat eaters that eat meat eaters (example: Owl that eats snake)

Core

Earth's innermost layer composed of the densest elements.

Lithosphere

Earth's outer layer - a cool rigid layer, 15km to 300km thick, that includes the crust and the uppermost part of the mantle. It is divided into huge pieces called tectonic plates

Crust

Earth's thin outer layer composed almost entirely of light elements

Sulfur cycle

Most of the earth's sulfur is tied up in rocks and salts or buried deep in the ocean in oceanic sediments. Sulfur can also be found in the atmosphere. It enters the atmosphere through both natural and human sources. Natural recourses can be for instance volcanic eruptions, bacterial processes, evaporation from water, or decaying organisms. When sulfur enters the atmosphere through human activity, this is mainly a consequence of industrial processes where sulfur dioxide (SO2) and hydrogen sulfide (H2S) gases are emitted on a wide scale. When sulfur dioxide enters the atmosphere it will react with oxygen to produce sulfur trioxide gas (SO3), or with other chemicals in the atmosphere, to produce sulfur salts. Sulfur dioxide may also react with water to produce sulfuric acid (H2SO4). Sulfuric acid may also be produced from demethylsulphide, which is emitted to the atmosphere by plankton species. All these particles will settle back onto earth, or react with rain and fall back onto earth as acid deposition/ acid rain. The particles will than be absorbed by plants again and are released back into the atmosphere, so that the sulphur cycle will start over again; sulfur makes up proteins and vitamins.

Assimilation

Nitrates are assimilated by plants through their root hairs. Heterotrophic organisms cannot absorb nitrogen as plants do, so they acquire nitrogen-based compounds through the food they eat. Since plants are the base of the food chain, the nitrogen-based compounds they have assimilated into their tissue will continue to pass from one organism to another (through consumption) as matter and energy transfer through the ecosystem's food web.

Bioaccumulation

Progressive increase in the amount of a substance in an organism or part of an organism which occurs because the rate of intake exceeds the organism's ability to remove the substance from the body.

Evaporation

Solar energy causes evaporation, where liquid water is changed into water vapor in the atmosphere.

Residency time

The amount of time that a chemical is held in one place, such as in an exchange pool or reservoir

Secondary succession

The ecological succession that occurs on a preexisting soil after the primary succession has been disrupted or destroyed due to a disturbance that reduced the population of the initial inhabitants.

Groundwater

The fresh water that flows through rocks and open spaces below the Earth's surface. Most of the fresh water that people access is groundwater, flowing underground. Aquifers are where some precipitation sinks through the soil and rock formations to underground layers of rock, sand, or gravel and is then stored as groundwater.

Niche

The role or function of an organism or species in an ecosystem

Transpiration

Transpiration is the process by which moisture is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released to the atmosphere; essentially evaporation of water from plant leaves.

Unconfined Aquifer

Water is stored in permeable rocks and sediment through which it can flow freely. Hence, water in this type of aquifer can flow to plant roots or bubble up to the surface as a spring.

Precipitation

When gravity draws Earth's water back to the surface. (example: rain, snow, sleet, dew)

Biomes

a large naturally occurring community of flora and fauna occupying a major habitat (example: tundra)

Reservoir

a place, region, or location where a biogeochemical element is in its highest concentration. Elements being cycled are held and stored for some time in reservoirs. Some elements have several reservoirs while others have one. Generally, reservoirs are abiotic factors while exchange pools are biotic factors. (Example: coal or fossil fuels are reservoirs for carbon.)

Trophic level

a position in a food chain occupied by a group of organisms with similar feeding modes (example: producers)

Aquifer

a rock layer that stores and allows the flow of ground water

Symbiotic relationships

a special type of interaction between species. Sometimes beneficial, sometimes harmful, these relationships are essential to many organisms and ecosystems, and they provide a balance that can only be achieved by working together.

Stratosphere

above troposphere (temperatures rise as altitude increases because the ozone absorbs the sun's UV energy

Producer

an autotrophic organism; first trophic level in a food chain; plants

Decomposer

an organism that breaks down other dead organisms into nutrients. (example: bacteria, fungi)

Secondary Consumers

animals that eat herbivores; meat eaters (example: snake that eats rabbits)

Confined Aquifer

are surrounded by impermeable layers of rock that don't allow water to move through them. Thus, confined aquifers create underground storage containers for the water they contain.

Troposphere

atmospheric layer nearest the Earth's surface

Respiration

breaks down glucose, releases stored energy for use in plants and animals, occurs in the mitochondria inside each cell. This process releases carbon dioxide, water, and energy.

Intraspecific Competition

competition involving organisms of different species. Predation - one member of a species (predator) feeds directly on all or part of a member of a different species

Interspecific Competition

competition involving organisms of the same species

Nitrogen fixation

conversion of atmospheric nitrogen (N2) into reactive compounds such as ammonia (NH3) and nitrate (NO3-). The breaking down of the bonds requires a great deal of energy and occurs by either abiotic fixation (lightning, cosmic radiation) or biological fixation (bacteria)

Ammonification

decomposing microogranisms such as bacteria and fungi break down nitrogenous wastes and organic matter found in animal wastes and dead plants and animals and convert it to inorganic ammonia (NH3) for absorption by plants as ammonium ions. Therefore, decomposition rates affect the level of nutrients available to primary producers.

Phosphorus cycle

does not include atmosphere; phosphorus enters the biosphere almost entirely from the soil/ rocks through absorption by plant roots. Weathering and erosion of rocks gradually release phosphorus as phosphate ions, which are soluble in water. Land plants need phosphate as a fertilizer or nutrient. When plant materials and waste products decay through bacterial action, the phosphate is released and returned to the environment for reuse.

Heterotroph

eats other organisms to get your energy, also known as consumers

Climax Community

ecological communities in which populations of plants or animals remain stable and exist in balance with each other and their environment. A climax community is the final stage of succession, remaining relatively unchanged until destroyed by an event such as fire or human interference.

Greenhouse effect

gases trap heat near the earth's surface

Species

general term for anything that can breed and produce offspring

Primary succession

gradual establishment of biotic communities in lifeless areas with no soil or bottom sediment

Population

group of the same organisms in a specific area

Community

groups of various populations interacting in an area

Primary consumers

herbivores; organisms that eat autotrophs/ producers; plant eaters (example: rabbits)

Mutualism

interaction that benefits both species by providing each with food, shelter, or some other resource

Commensalism

interaction that benefits one species but has little, if any, affect on the other

Biotic

living factors in an environment

Law of Conservation of Matter

matter and energy can neither be created nor destroyed. This relates to Environmental Science since everything we think we have thrown away at one point stays with us in some form.

Abiotic

nonliving factors in an environment

Predation

one member of a species (predator) feeds directly on all or part of a member of a different species

Parasitism

organism feeds on the body of, or the energy used by, another organism (host), usually by living on the host.

Detrivore

organisms that feed on decomposing organic matter such as poop or detritus. (example: earth worms)

Nitrification

process by which ammonia is oxidized into nitrate ions (NO2) and then to nitrate ions (NO3-), which is the form most usable by plants.

Denitrification

process by which nitrates are reduced to gaseous nitrogen (N2) and lost to the atmosphere. This process occurs by facultative anaerobes in anaerobic environments. Farmers with waterlogged fields and soild that have high clay content are especially vulnerable to nitrogen losses due to denitrification.

Law of Tolerance

range of conditions that an organism can withstand; each ecosystems population's ability to adjust to variations in its physical and chemical environment

Net Primary Productivity (NPP)

rate at which producers use photosynthesis to produce and store energy minus the rate at which they use some of this stored chemical energy through aerobic respiration; energy left over for use by consumer; usually limits number of consumers.

Energy pyramid

shows how energy in the ecosystem is distributed among the trophic levels

Photosynthesis

the chemical process by which green plants convert sunlight into sugar, creates glucose and oxygen gas.

Pioneer Species

the first to colonize previously disrupted or damaged ecosystems in ecological succession (example: lichens)

Mantle

the layer beneath the crust, makes up 64 percent of the mass of the Earth. It is approximately 2900 km thick and is made of rocks of medium density

Habitat

the natural home or environment of an animal, plant, or other organism

Ecological succession

the observed process of change in the species structure of an ecological community over time

Food chain

the path of food from a given final consumer back to a producer.

Autotroph

the producers in a food chain such as plants and algae

Exchange pool

when chemicals are held for only short periods of time. Examples of exchange pools include plants and animals, which temporarily use elements in their systems and release them back into the air or surrounding medium. Exchange pools tend to be biotic factors while reservoirs tend to be abiotic factors. (example: Carbon is held for a relatively short time in plants and animals when compared to fossil fuel deposits).