OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

Which of the following is a major impact of overgrazing?

1. Improved soil structure

2. Clearing of natural vegetation, leading to soil erosion

3. Increased biodiversity in the region

4. Enhancement of ecosystem stability

The correct answer is: Clearing of natural vegetation, leading to soil erosion

Overgrazing leads to the clearing of natural vegetation, which has significant consequences for the soil and the surrounding ecosystem. When animals graze excessively, they consume too much of the plant cover, preventing vegetation from regenerating. Without this vegetative cover, the soil becomes more vulnerable to erosion by wind and water. The plant roots that typically help anchor the soil in place are weakened or removed, which can result in the loss of topsoil and degradation of land quality. This process can create a cycle of soil erosion that makes it increasingly difficult for vegetation to recover, ultimately leading to further loss of biodiversity and potential desertification. Such changes negatively impact the ecosystem, reducing its ability to support various life forms and destabilizing the habitats for many species. The other options presented do not accurately reflect the consequences of overgrazing; improved soil structure, increased biodiversity, and enhanced ecosystem stability are not outcomes associated with this practice.