Keystone Ecology Practice Test

The term that defines a close interaction between two different biological species is symbiosis. Symbiosis encompasses various forms of interactions where two species live in close association with each other, which can include beneficial, harmful, or neutral relationships. This broad definition includes mutualism, where both species benefit, and commensalism, where one species benefits while the other is neither helped nor harmed.

By recognizing symbiosis as the overarching term, it is clear that it covers the spectrum of interspecies relationships and emphasizes the significance of close biological partnerships in an ecosystem. Understanding this concept helps in appreciating the intricate balance of ecological interactions that sustain biodiversity.