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| 91722463 | Biodiversity | Variety of different species, genetic variabilty among individuals within each species, variety of ecosystems, and functions such as energy flow and matter cycling needed for the survival of species and biological communities. | |
| 91722464 | Developed country | Country that is highly industrialized and has a high per capita GNP. | |
| 91722465 | Developing country | Country that has low to moderate industrialization and low to moderate per capita GNP. | |
| 91722466 | Ecological footprint | Amount of biologically productive land and water needed to supply each person or population with the renewable resources they use and to absorb or dispose of the wastes from such resource use. | |
| 91722467 | Economic Depletion | Exhaustion of 80% of the estimated supply of a nonrenewable resource. | |
| 91722468 | Exponential Growth | Growth in which some quantity, such as population size or economic output, increases at a constant rate per unit of time | |
| 91722469 | Multiple Uses | Use of an ecosystem such as a forest for a variety of purposes such as timber harvesting, wildlife habitat, watershed protection, and recreation. | |
| 91722470 | Nonpoint Source | Large or dispersed land areas such as crop fields, streets, and lawns that discharge pollutants into the environment over a large area. | |
| 91722471 | Nonrenewable Resource | Resource that exists in a fixed amount in various places in the earth's crust and has the potential for renewal by geological, physical, and chemical processes taking place over hundreds of millions to billions of years. | |
| 91722472 | Per capita GDP | Annual gross domestic product of a country divided by its total population at midyear. | |
| 91722473 | Point Source | Single identifiable source that discharges pollutatants into the environment. | |
| 91722474 | Pollution Prevention | Device of process that prevents a potential pollutant from forming or entering the environment or sharply reduces the amount entering the environment. | |
| 91722475 | Precautionary Principle | When there is scientific uncertainty about potentially serious harm from chemicals or technologies, decision makers should act to prevent harm to humans and the environment. | |
| 91722476 | Recycling | Collecting and reprocessing a resource so that it can be made into new products. | |
| 91722477 | Renewable Resource | Resource that can be replenished rapidly through natural processes. | |
| 91722478 | Reuse | Using a product over and over again in the same form. | |
| 91722479 | Solar Energy | Direct radiant energy from the sun and a number of indirect forms of energy produced by the direct input. | |
| 91722480 | Sustainable Living | Taking no more potentially renewable resources from the natural world than can be replenished naturally and not overloading the capacity of the environment to cleanse and renew itself by natural processes. | |
| 91722481 | Tragedy of the Commons | Depletion or degradation of a potentially renewable resource to which people have free and unmanaged access. | |
| 91743561 | Conservation | Sensible and careful use of natural resources by humans. | |
| 91743562 | EPA | U.S. Environmental Protection Agency; responsible for managing federal efforts to control air and water pollution, radiation and pesticide hazards, environmental research, hazardous waste, and solid waste disposal. | |
| 91743563 | Preservationist | Person concerned primarily with srtting aside or protecting undisturbed naturalareas from harmful human activities. | |
| 91743564 | Acid Solution | Any water solution that has more hudrogen ions than hydroxide ions; any water solution with a pH less than 7. | |
| 91743565 | Basic Solution | Water solution with more hydroxide ions than hydrogen ions; water solution with a pH greater than 7. | |
| 91743566 | Biodegradable | Capable of being broken down by decomposers. | |
| 91743567 | Energy Efficiency | Percentage of the total energy input that does useful work and is not converted into low-quality, usually useless heat in an energy conversion system or process. | |
| 91743568 | Energy Quality | Ability of a form of energy to do useful work. | |
| 91743569 | First Law of Thermodynamics | In any physical or chemical change, no detectable amount of energy is created or destroyed, but in these processes energy can be changed from one form to another. | |
| 91743570 | Half-life | Time needed for one-half of the nuclei in a radioisotope to emit its radiation. | |
| 91743571 | High-quality Energy | Energy that is concentrated and has great ability to perform useful work. | |
| 91743572 | Hydrocarbon | Organic compound of hydrogen and carbon atoms. | |
| 91743573 | Ion | Atom or group of atoms with one or more positive or negative electrical charges. | |
| 91743574 | Isotopes | Two or more forms of a chemical element that have the same number of protons but different mass numbers because they have different numbers of neutrons in their nuclei. | |
| 91743575 | Low-quality Energy | Energy that is dispersed and has little ability to do useful work. | |
| 91743576 | Negative Feedback Loop | Situation in which a change in a certain direction provides information that causes a system to change less in that direction. | |
| 91743577 | ph | Numerical value that indicates the relative acidity or alkalinity of a substance on a scale of 0 to 14, with the neutral point at 7. | |
| 91743578 | Pollutant | A particular chemical or form of energy that can adversely affect the health, survival, or activities of humans or other living organisms. | |
| 91743579 | Positive Feedback Loop | Situation in which a change in a certain direction provides information that causes a system to change further in the same direction. | |
| 91743580 | Parts Per Billion (ppb) | Number of parts of a chemical found in 1 billion parts of a particular gas, liquid or solid. | |
| 91743581 | Parts Per Million (ppm) | Number of parts of a chemical found in 1 million parts of a particular gas, liquid, or solid. | |
| 91890006 | Parts Per Trillion (ppt) | Number of parts of a chemical found in 1 trillion parts of a particular gas, liquid or solid. | |
| 91890007 | Radioactivity | Nuclear change in which unstable nuclei of atoms spontaneously shoot out "chunks" of mass, energy, or both at a fixed rate. | |
| 91890008 | Radioisotope | Isotope of an atom that sponateously emits one or more types of radioactivity. | |
| 91890009 | Second Law of Thermodynamics | In any conversion of heat energy to useful work, some of the initial energy input is always degraded to a lower-quality, more dispersed, less useful energy, usually low temperauture heat that flows into the environment. | |
| 91890010 | Synergistic Interaction | Interaction of two or more factors or processes so that the combined effect is greater than the sum of their seperate effects. | |
| 91890011 | Abiotic | Nonliving. | |
| 91890012 | Acid Deposition | The falling of acids and acid-forming compunds from the atmosphere to the earth's surface. | |
| 91890013 | Aerobic Respiration | Complex process that occurs in the cells of most living organisms, in which nutrient organic molecules such as glucose combine with oxygen and produce carbon dioxide, water, and energy. | |
| 91890014 | Anaerobic Respiration | Form of cellular respiration in which some decomposers get the energy they need through the breakdown of glucose in the absence of oxygen. | |
| 91890015 | Aquatic | Pertaining to water. | |
| 91890016 | Autotroph | Organism that uses solar energy or chemical energy to manufacture the organic compunds it needs as nutrients from simple inorganic compunds obtained from its environment. | |
| 91890017 | Biogeochemical Cycle | Natural processes that recycle nutrients in various chemical forms from the nonliving environment to living organisms and then back to the nonliving environment. | |
| 91890018 | Biomass | Organic matter produced by plants and other photosynthetic producers; total dryweight of all living organisms that can be supported at each trophic level in a food chain or web. | |
| 91890019 | Biosphere | Zone of earth where life is found. | |
| 91890020 | Biotic | Living organisms. | |
| 91890021 | Carbon Cycle | Cyclic movement of carbon in different chemical forms from the environment to organisms and then back to the environment. | |
| 91890022 | Chemosynthesis | Process in which certain organisms extract inorgainc compounds from their environment and convert them into orgainc nutrient compounds without the presence of sunlight. | |
| 91933186 | Community | Populations of all species living and interacting in an area at a particular time. | |
| 91933187 | Consumer | Organism that cannot synthesize the orgainc nutrients it needs and gets its organic nutrients | |
| 91933188 | Decomposer | Organism thst diges parts of dead organisms and cast-off fragments and wastes of living organisms by breaking down the complex organic molecules in those materials into simpler inorganic compounds and then absorbing the soluble nutrients. | |
| 91933189 | Detritivore | Consumer organism that feeds on detritus, parts of dead organisms, and cast-off fragments and wastes of living organisms. | |
| 91933190 | Detritus | Parts of dead organisms and cast-off fragments and wastes of living organisms. | |
| 91933191 | Detritus Feeder | Organism that extracts nutrients from fragments of dead organims and their cast-off parts and organic wastes. | |
| 91933192 | Dissolved Oxygen Content | Amount of oxygen gas dissolved in a given volume of water at a particular temperature and pressure, often expressed as a concentration in parts of oxygen per million parts of water. | |
| 91933193 | Ecological Efficiency | Percentage of energy transferred from one trophic level to another in a food chain or web. | |
| 91933194 | Ecosystem | Community of different species interacting with one another and with the chemical and physical factors making up its nonliving environment. | |
| 91933195 | Food Chain | Series of organisms in which each eats or decomposes the preceding one. | |
| 91933196 | Food Web | Complex network of many interconnected food chains and feeding relationships. | |
| 91933197 | Heterotroph | Orgainism that cannot synthesize the organic nutrients it needs and gets its organic nutrients by feeding on the tissues of producers or of other consumers. | |
| 91933198 | Hydrosphere | The earth's liquid water. | |
| 91933199 | Infiltration | Downward movement of water through soil. | |
| 91933200 | Leaching | Process in which various chemicals in upper layers of soil are dissolved and carried to lower layers, and in some cases, to groundwater. | |
| 91933201 | Limiting Factor | Single factor that limits the growth. abundance, or distrubution of the population of a species in an ecosystem. | |
| 91933202 | Limiting factor principle | Too much or too little of any abiotic factor can limit of prevent growth of a population of a species in an ecosystem, even if all other factors are at or near the optimum range of tolerance for the species. | |
| 91933203 | Natural Greenhouse Effect | Heat buildup in the troposphere because of the presence of certain gases, called greenhouse gases. | |
| 91933204 | Net Primary Productivity | Rate at which all the plants in an ecosystem produce net useful chemical energy. | |
| 91933205 | Nitrogen Cycle | Cyclic movement of nitrogen in different chemical forms from the environment to organisms and then back to the environemnt. | |
| 91933206 | Nitrogen Fixation | Conversion of atmospheric nitrogen gas into forms useful to plants by lightening, bacteria, and cyanobacteria. | |
| 91933207 | Nutrient Cycle | A Biogeochemical Cycle. | |
| 91933208 | Organism | Any form of life. | |
| 91933209 | Percolation | Passage of a liquid through the spaces of a porous material such as soil. | |
| 91933210 | Phosphorous Cycle | Cyclic movement of phosphorous in different chemical forms from the environement to organisms and then back to the environemnt. | |
| 91933211 | Photosynthesis | Complex process that takes place in cells of green plants. | |
| 91933212 | Population | Group of individual organisms of the same species living in a particular area. | |
| 91933213 | Precipitation | Water in the form of rain, sleet, hail, and snow that falls from the atmosphere onto the land and bodies of water. | |
| 91933214 | Primary Consumer | Organism that feeds on all or part of plants or on other producers. | |
| 91933215 | Gross Primary Productivity | The rate at which an ecosystem's producers capture and store a given amount of chemical energy as biomass in a given length of time. | |
| 91933216 | Net Primary Productivity | Rate at which all the plants in an ecosystem produce net useful chemical energy. | |
| 91933217 | Producer | Autotroph. | |
| 91933218 | Prokaryotic Cell | Cell that doesn't have a distinct nucleus. | |
| 91933219 | Pyramid of Energy Flow | diagram representing the flow of energy through each trophic level in a food chain or food web. | |
| 91933220 | Range of Tolerance | Range of physical and chemical conditions that must be maintained for populations of a particular species to stay alive and grow, develop, and function normally. | |
| 91933221 | Salinity | Amount of various salts dissolved in a given volume of water. | |
| 91933222 | Scavenger | Organism that feeds on dead organisms that were killed by other organisms or died naturally. | |
| 91933223 | Secondary Consumer | Organism that feeds only on primary consumers. | |
| 91933224 | Species | Group of organisms that resemble one another in appearence, behavior, chemical makeup and processes, and genetic structure. | |
| 91933225 | Species Diversity | Number of different species and their relative abundances in a given area or community. | |
| 91933226 | Sulfur Cycle | Cyclic movement of sulfur in different chemical forms from the environment to organisms and then back to the environment. | |
| 91933227 | Terrestrial | Pertaining to land. | |
| 91933228 | Tertiary (higher level) | Animals that feed on animal-eating animals. | |
| 91933229 | Trophic Level | All organisms that are the same number of of energy transfers away from the original source of energy that enters an ecosystem. | |
| 91933230 | Troposphere | Innermost layer of the atmoshpere. | |
| 91933231 | Water Cycle | Biogeochemical cycle that collects, purifies, and distributes the earth's fixed supply of water from the environemnt to living organisms and then back to the environment. | |
| 91933232 | Benthos | Bottom-dwelling organisms. | |
| 91933233 | Cyanobacteria | Single-celled, prokaryotic, microscopic organisms. | |
| 91933234 | Estuary | Partially enclosed costal area at the mouth of a river where its freshwater, carrying fertile silt and runoff from the land, mixes with salty seawater. | |
| 91933235 | Eutrophic Lake | Lake with a large or excessive supply of plant nutrients, mostly nitrates and phosphates. | |
| 91933236 | Invertebrates | Animals that have no backbones. | |
| 91995012 | Mangrove Swamps | Swamps found on the coastlines in warm tropical climates. | |
| 91995013 | Mesotrophic Lake | Lake with a moderate supply of plant nutrients. | |
| 91995014 | Oligotrophic Lake | Lake with a low supply of plant nutrients. | |
| 91995015 | Phytoplankton | Small, drifting plants, mostly algae and bacteria, found in aquatic systems. | |
| 91995016 | Plankton | Small plant organisms and animal organisms that float in aquatic ecosystems. | |
| 92343668 | Runoff | Freshwater from precipitation and melting ice that flows on the earth's surface into nearby streams, lakes, wetlands and reservoirs. | |
| 92343669 | Transpiration | Process in which water is absorbed by the root systems of plants, moves up through the plants, passes through pores in their leaves or other parts, and evaporates into the atmosphere as water vapor. | |
| 92343670 | Watershed | Land area that delivers sediment, and dissolve substances via small streams to a major stream. | |
| 92343671 | Zooplankton | Animal plankton. Small floating herbivores that feed on plant plankton. | |
| 92343672 | Commercial Extinction | Depletion of the population of a wild species used as a resource to a level at which it is no longer profitable to harvest the species. | |
| 92343673 | Overfishing | Harvesting so many fish of a species, especially immature fish, that not enough breeding stock is left to replenish the species and it becomes unprofitable to harvest them. | |
| 92343674 | Wetland | Land that is covered all or part of the time with salt water or freshwater, excluding streams, lakes, and the open ocean. |
