What term describes two species that influence each other, both positively or negatively?

• A. Symbiosis
• B. Predator-Prey
• C. Mutualism
• D. Competition

Answer: (A)

Symbiosis describes close interactions between two species that can affect one or both in positive or negative ways. This broad term includes mutualism (both benefit), parasitism (one benefits, the other is harmed), and commensalism (one benefits, the other is unaffected). The key idea is the two species influence each other through a lasting association, which fits the scenario of positive or negative effects between species. A predator-prey relationship is specific and involves one benefit and one harm, not a two-way influence described by symbiosis. Mutualism is a type of symbiosis with both benefiting, but the umbrella term that covers all such reciprocal influences is symbiosis. Competition involves species vying for resources and is not focused on a close, living-together relationship like symbiosis.