Living Environment Regents Practice Test

Why can a stable ecosystem support high biodiversity?

1. Many species are competing for the same resources

2. Each species occupies a different niche

3. All species are interdependent

4. There are no invasive species present

The correct answer is: Each species occupies a different niche

A stable ecosystem can support high biodiversity primarily because each species occupies a different niche. A niche refers to the role or function of an organism within its environment, including how it gets its energy, interacts with other organisms, and contributes to the ecosystem's structure and function. When species have distinct niches, they reduce competition for the same resources, allowing multiple species to coexist within the same environment. This differentiation in roles enables ecosystems to support a wider variety of species, each contributing to the overall health and balance of the ecosystem. In contrast, competition for the same resources, while present in any ecosystem, does not enhance biodiversity; rather, it can limit the number of species that can thrive. Interdependence among species is crucial for ecosystem dynamics, but relying solely on interdependence does not ensure high biodiversity either—many species might depend on the same resources, leading again to competition. The presence or lack of invasive species can impact ecosystem stability, but ecosystems can be stable and support high biodiversity even in the presence of invasive species, provided that they don't dominate the ecological niches.