| A | B |
|---|
| biosphere | All of the ecosystems on Earth together |
| ecology | the study of interactions between organisms |
| abiotic factor | nonliving physical features of the environment |
| biotic factor | living or once-living organisms of the environment |
| population | individual organisms of the same species |
| community | groupsof populationsin an area that interact |
| ecosystem | made of a biotic community and abiotic factors |
| population density | the size of a population that occupies a limited area |
| limiting factor | any biotic or abiotic factor that restricts the number of individuals in a popluation |
| carrying capacity | the largest number of individuals an environment can support |
| symbiosis | any close relationship between two or more different species |
| habitat | the physical location where an organism lives |
| niche | the role of an organism in its ecosystem |
| food chain | the path of food energy passing from one organism to another |
| food web | overlapping food chains showing many organisms feed on more than one level |
| ecological pyramid | model of energy transfer from producers through successive levels of organisms |
| producer | an organism that turns the sun's energy into food |
| consumer | an organism that eats another organism |
| herbivore | a plant eater |
| carnivore | a meat eater |
| omnivore | eats both plants and animals |
| decomposer | breaks down dead organisms |
| symbiosis | a relationship between two organisms |
| mutualism | a relationship between two organisms in which both benefit |
| parasitism | a relationship between two organisms where one is harmed |
| commensalism | a relationsip between two organisms when one benefits and the other is unharmed |
