| A | B |
|---|
| biosphere | consists of all life on Earth and all parts of the Earth, including land, water, and the atmosphere |
| ecology | scientific study of interactions among organisms and between organisms and their physical environment |
| biotic factor | any living part of the environment with which an organism might interact |
| abiotic factor | any nonliving part of the environment |
| species | group of similar organisms that can breed and produce fertile offspring |
| population | group of individuals that belong to the same species and live in the same area |
| community | assemblage of different populations that live together in a defined area |
| ecosystem | all the organisms that live in a place, together with their physical environment |
| biome | a group of ecosystems that share similar climates and typical organisms |
| autotroph | organisms that capture energy from the sun and convert it into forms that living cells can use |
| primary producer | first producers of energy-rich compounds that are later used by other organisms |
| photosynthesis | captures light energy and uses it to power chemical reactions that convert CO2 and H2O into oxygen and energy-rich carbohydrates |
| chemosynthesis | process in which organisms use chemical energy to produce carbohydrates |
| heterotrophs | organisms that must acquire energy from other organisms |
| consumers | another name for heterotrophs |
| carnivores | kill and eat other animals |
| herbivores | obtain energy and nutrients by eating plant parts |
| scavengers | animals that consume the dead carcasses of other animals |
| omnivores | animals whose diets include both plants and animals |
| decomposers | feed by chemically breaking down organic matter |
| detritivores | feed on detritus particles |
| food chain | series of steps in which organisms transfer energy by eating and being eaten |
| phytoplankton | floating algae |
| food web | complex network of feeding interactions |
| zooplankton | diverse group of small swimming animals that feed on marine algae |
| trophic level | each step in a food chain or food web |
| ecological pyramid | shows the relative amount of energy or matter contained within each trophic level in a given food chain or food web |
| biomass | total amount of living tissue within a given trophic level |
| biogeochemical 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 |
| nutrients | chemical substances that an organism needs to sustain life |
| nitrogen fixation | process in which bacteria convert nitrogen gas into ammonia |
| denitrification | process through which bacteria convert nitrogen gas into ammonia |
| limiting nutrient | the nutrient whose supply limits productivity in an ecosystem |
