A Level Biology Practice Exam

Simpson's Index of Diversity primarily evaluates species richness and species evenness within a given community. Species richness refers to the total number of different species present in an area, while species evenness measures how evenly the individuals are distributed among those species. A high value of the Simpson's Index indicates a more diverse community, where both the number of species and their relative abundances are considered, providing insights into the stability and resilience of the ecosystem.

The other options, while related to aspects of biodiversity, do not precisely reflect what Simpson's Index measures. For example, species abundance and distribution, while important, are broader concepts that encompass multiple factors not specifically captured by the index. Similarly, genetic variation pertains to diversity within a species rather than between different species, and ecological roles relate more to the functional aspects of species interactions rather than their numerical and proportional representation within a community.