A Level Biology Practice Exam

What are selection pressures?

1. Factors that promote genetic diversity

2. Factors that lead to increased genetic mutation

3. Factors affecting an organism's chance of survival or reproductive success

4. Factors that ensure equal competition among species

The correct answer is: Factors affecting an organism's chance of survival or reproductive success

Selection pressures are defined as factors affecting an organism's chance of survival or reproductive success, making your choice the correct one. These pressures can come from various sources, such as predation, competition for resources, disease, and environmental changes. They play a key role in natural selection, as they influence which individuals within a population are more likely to survive and reproduce based on their traits. Genetic diversity and mutation, though relevant to evolution, are not the primary definition of selection pressures. Selection pressures do not guarantee equal competition among species either; rather, they create varying degrees of competition depending on the specific circumstances of the environment and the characteristics of the organisms involved. Therefore, understanding selection pressures is crucial to studying how species adapt and evolve over time.