Massachusetts Comprehensive Assessment System (MCAS) Biology Practice Test

Which of the following best describes the concept of carrying capacity?

1. The maximum number of a species that an ecosystem can support

2. The speed of population growth over time

3. The number of individuals competing for resources

4. The number of species in an area

The correct answer is: The maximum number of a species that an ecosystem can support

Carrying capacity refers to the maximum number of individuals of a particular species that an ecosystem can sustainably support over time. This concept is crucial in understanding population dynamics and ecology, as it is determined by the availability of resources such as food, water, shelter, and other environmental conditions that influence growth and survival. When a population exceeds its carrying capacity, it can lead to overconsumption of resources, resulting in detrimental effects such as habitat degradation, food shortages, and increased competition, which may ultimately lead to a decline in the population. Understanding carrying capacity helps ecologists manage wildlife populations, conserve habitats, and predict how changes in the environment can affect species sustainability. The other options address different aspects of population studies. For instance, the speed of population growth relates to how quickly a species increases in number, which does not define its capacity limit. The number of individuals competing for resources is more about population dynamics than carrying capacity itself, and the number of species in an area refers to biodiversity, which is unrelated to the specific limits of a single species' population. Thus, the correct choice encapsulates the essence of carrying capacity effectively.