A Level Biology Practice Exam

What does biodiversity refer to?

1. The number of species that have gone extinct

2. The variety of living organisms present in an area

3. The total biomass of all organisms in an ecosystem

4. The genetic variability within a single species

The correct answer is: The variety of living organisms present in an area

Biodiversity refers to the variety of living organisms present in an area, encompassing the different species, their genetic variability, and the ecosystems they inhabit. This definition highlights the richness and complexity of life forms, and recognizes the importance of both species diversity and ecosystem diversity in maintaining the health and stability of ecological systems. When measuring biodiversity, researchers look at the range of species in a particular habitat, which reflects the ecological balance and functional diversity necessary for resilience against changes like climate shifts or habitat destruction. The other options are more specific aspects or consequences of biodiversity, but they do not encapsulate its broad and inclusive definition. For instance, the number of extinct species focuses solely on loss rather than the current variety, while total biomass measures quantity rather than diversity. Genetic variability within a single species highlights diversity at a micro level but does not encompass the variety of organisms across multiple species. The breadth of biodiversity captures the interconnections and the abundance of life present in different ecosystems.