| A | B |
| Pioneer Species | first species in an area |
| Population Density | number of individuals of a population in an area |
| Community | all the different populations that live together in an area |
| Secondary Succession | series of changes after a disruption in an existing ecosystem |
| host | the organism another is living on |
| Carrying Capacity | largest population an environment can support |
| Symbiotic Relationships | mutualism, commensalism, parasitism |
| Organism | smallest unit of ecological organization |
| Niche | who eats what, when |
| Ecology | the study of how things interact in an environment |
| abiotic factors | sunlight, carbon dioxide, soil |
| biotic factors | grass, moss, cows, people |