Biology Regents Practice Exam

What happens when an animal population exceeds the carrying capacity of its environment?

1. The birth rate will increase

2. Both the birth rate and death rate will decrease

3. The death rate will increase

4. Neither the birth rate nor the death rate will decrease

The correct answer is: The death rate will increase

When an animal population exceeds the carrying capacity of its environment, resources such as food, water, and space become limited. This scarcity leads to increased competition among individuals for the available resources. As a result, the stress on the population can cause an increase in the death rate. Animals may not find enough food to sustain their populations, leading to malnutrition and starvation. Additionally, overcrowding can create conditions that facilitate the spread of disease, further contributing to a higher death rate. This dynamic ultimately works to bring the population size back down towards the carrying capacity of the environment. In this context, the other options wouldn't accurately reflect the biological principles at play. For example, an increase in the birth rate would typically only occur when resources are abundant, and a decrease in both birth and death rates would not occur during resource scarcity. Additionally, stating that neither birth nor death rates would decrease contradicts the consequences of overpopulation in an ecosystem.