| A | B |
|---|
| Individual | A single organism. |
| Population | All the individuals of one kind (one species) in a specified area at one time. |
| Community | All the interacting populations in a specified area. |
| Abiotic factors | The nonliving parts of an ecosystem. |
| Biotic factors | The living parts of an ecosystem. |
| Ecosystem | A system of interacting organisms and nonliving factors in a specified area. |
| Biome | A collection of ecosystems that have similar environments and organisms. |
| Biosphere | The sum total of all living organisms. |
| Competition | When several kinds of organisms in an ecosystem require the same resources, such as food sources, territory, or mates. |
| Cooperation | The process of groups of organisms working or acting together for common, mutual, or some underlying benefit. |
| Predation | A biological interaction where one organism, the predator, kills and eats another organism, its prey. |
| Symbiosis | A relationship between species in which one or both species rely on each other; one or both species benefit from the relationship. |
| Mutualism | A relationship between species in which both benefit, like clownfish and sea anemone. |
| Parasitism | A relationship between species in which one benefits while the other is harmed, like ticks on a dog. |
| Commensalism | A relationship in which one organism (or species) benefits and the other is neither helped nor harmed. |
| Limiting factors | Any biotic or abiotic component of the ecosystem that controls the size of a population. |
| Population study | An experiment in which the observer collects data over time for one population in an ecosystem. |
| Observational study | An experiment in which the observer collects data over time without interacting with the area of study. |
