Which term describes a chain reaction where one event leads to subsequent effects?

• A. Indirect effect
• B. Food web
• C. Competition
• D. Energy

Answer: (A)

In ecosystems, a change in one part can ripple through other parts via links between species and processes. This spreading influence, even though it isn’t a direct, one-step result, is called an indirect effect. For example, removing a top predator can boost prey numbers, which then increase herbivory on plants and shift the plant community. That sequence shows how an initial event leads to subsequent effects through indirect interactions.

A food web is the map of who eats whom, not the sequence of downstream consequences. Competition is about organisms vying for the same resources, not the cascade of effects from one change. Energy describes how energy moves through trophic levels, not the propagation of effects after an initial event. Thus, indirect effect best describes a chain reaction where one event leads to subsequent effects.