Massachusetts Comprehensive Assessment System (MCAS) Biology Practice Test

Which factor can affect population size and biodiversity?

1. Solar energy patterns

2. The color of local vegetation

3. Carrying capacity

4. The shape of earth's tectonic plates

The correct answer is: Carrying capacity

Carrying capacity is a crucial factor that influences both population size and biodiversity within an ecosystem. It refers to the maximum number of individuals of a particular species that an environment can sustain indefinitely without degrading the habitat. When a population exceeds its carrying capacity, resources such as food, water, and space become limited, leading to increased competition. This competition can result in a decline in population size due to factors like starvation or disease. Additionally, a stable carrying capacity can support a diverse array of species, as it allows for the coexistence of different organisms that occupy various ecological niches. Conversely, if the carrying capacity is severely reduced, it can lead to a loss of biodiversity, as more sensitive species may not survive. In contrast, while solar energy patterns can influence the overall productivity of an ecosystem, and the color of local vegetation can affect certain animal behaviors, they don't have as direct an impact on population dynamics as carrying capacity does. The shape of Earth’s tectonic plates, on the other hand, primarily affects geological features and can indirectly impact ecosystems but is not a direct factor in regulating population size or biodiversity in the same way that carrying capacity does.