| A | B |
|---|
| biosphere | part of Earth in which life exists including land, water, and air or atmosphere |
| species | a group of similar organisms that can breed and produce fertile offspring |
| population | group of individuals of the same species that live in the same area |
| community | assemblage of different populations that live together in a defined area |
| ecology | scientific study of interaction among organisms and between organisms and their environment |
| ecosystem | all the organisms that live in place, together with their nonliving environment |
| biome | a group of ecosystems that share similar climates and typical organisms |
| biotic factor | any living part of the environment with which an organism might interact |
| abiotic factor | physical, or nonliving, factor that shapes an ecosystem |
| autotroph | organism that is able to capture energy from sunlight or chemicals and use it to produce its own food from inorganic compounds; also called a producer |
| primary producer | first producer of energy-rich compounds that are later used by other organisms |
| photosynthesis | process used by plants and other autotrophs to capture light energy and use it to power chemical reactions that convert carbon dioxide and water into oxygen and energy-rich carbohydrates such as sugars and starches |
| chemosynthesis | process in which chemical energy is used to produce carbohydrates |
| heterotroph | organism that obtains food by consuming other living things; also called a consumer |
| consumer | organsim that relies on other organisms for its energy and food supply; also called heterotroph |
| carnivore | organism that obtains energy by eating animals |
| herbivore | organism that obtains energy by eating only plants |
| scavenger | animal that consumes the carcasses of other animals |
| omnivore | organism that obtains energy by eating both plants and animals |
| decomposer | organism that breaks down and obtains energy from dead organic matter |
| detritivore | organism that feeds on plant and animal remains and other dead matter |
| food chain | series of steps in an ecosystem in which organisms transfer energy by eating and being eaten |
| phytoplankton | photosynthetic algae found near the surface of the ocean |
| food web | network of complex interactions formed by the feeding relationships among the various organisms in an ecosystem |
| zooplankton | small freee-floating animals that form part of plankton |
| trophic level | each step ina food chain or food web |
| ecological pyramid | illustration of the relative amounts of energy or matter contained within eac trophic level in a given food chain or food web |
| biomass | total amount of living tissue within a given trophic level |
| biogeochemical cycle | process in which elements, chemical compounds, and other forms of matter are apssed from one organism to another |
| nutrient | chemical substance that an organism needs to sustain life |
| nitrogen fixation | process of converting nitrogen gas into nitrogen compounds that plants can absorb and use |
| denitrification | process by which bacteria convert nitrates into nitrogen gas |
| limiting nutrient | single essential nutrient that limits productivity in an ecosystem |
