A Level Biology Practice Exam

What is a genetic bottleneck?

1. Enhancing genetic diversity within a population

2. Increased genetic mutations in a population

3. A reduction in genetic diversity due to population decline

4. The introduction of new alleles through migration

The correct answer is: A reduction in genetic diversity due to population decline

A genetic bottleneck refers to a significant reduction in the size of a population, which can lead to a decrease in genetic diversity. This reduction can be caused by various factors such as natural disasters, habitat loss, or other events that drastically decrease the population size. As the population shrinks, only a small number of individuals contribute to the gene pool in subsequent generations, reducing the variety of alleles available and increasing the likelihood of inbreeding. This phenomenon is crucial in understanding how certain species may become more vulnerable to diseases and environmental changes due to the loss of genetic variation. Over time, the limited genetic diversity can affect the evolutionary potential of the population, hindering its ability to adapt to future changes or challenges in the environment.