Massachusetts Comprehensive Assessment System (MCAS) Biology Practice Test

What effect can overpopulation of a species have on an ecosystem?

1. It can lead to resource depletion and ecosystem imbalance

2. It always results in increase in biodiversity

3. It has minimal effects on the environment

4. It can enhance species survival

The correct answer is: It can lead to resource depletion and ecosystem imbalance

Overpopulation of a species can significantly disrupt an ecosystem, primarily leading to resource depletion and imbalance. When a species experiences rapid population growth, it often consumes resources such as food, water, and habitat space at an unsustainable rate. This intense competition for limited resources can result in shortages that negatively impact not only the overpopulated species but also other species within the ecosystem that rely on the same resources. Furthermore, as the population grows unchecked, it can outcompete other organisms, potentially driving them towards decline or extinction. This competition may also alter the structure of the community, leading to a loss of biodiversity as more and more species struggle to survive or adapt. In some cases, the initial success of the overpopulated species can even lead to a cascade of effects, disrupting trophic levels and altering predator-prey dynamics, which further destabilizes the ecosystem. In contrast, the other options do not accurately reflect the repercussions of overpopulation in an ecosystem. An increase in biodiversity is not a typical outcome of overpopulation; rather, it often leads to a decrease in it. Minimal effects on the environment are also unlikely, as substantial ecological changes often occur in response to significant population increases. Enhancing species survival would only apply under very specific and