The definition of biodiversity stated by the Convention on Biological Diversity (CBD) in 1992 was conceived as occurring on three different organizational levels: genetic, species, and ecosystems. However, current understanding of biodiversity includes other components, such as the number, abundance, composition, and spatial distribution of species and functional groups. This paper aimed to identify high school students' frameworks of biodiversity, to assess their conceptual understanding of biodiversity against scientific definitions, and to analyze the influence of sex and school location on students' understanding of biodiversity. By administering a written questionnaire in which ten different biodiversity scenarios were presented, each consisting of two environments which differed in certain biodiversity components, we asked students (n=321, 15-18 years old) to choose and argue their preference for biodiversity conservation. Students held a range of frameworks of biodiversity, with some of them being in agreement with scientific conceptualizations (idea of variance as the number of species, functional groups, and trophic relationships). However, students were strongly centered on species richness and undervalued population size, functional characters, species evenness, and alpha diversity. Biodiversity was associated with a notion of balance, by which a proportioned trophic chain prevents species extinction. Overall, students used few components of biodiversity in their argumentations, with no influence of school location or sex. We recommend that teachers fully integrate students' frameworks with more updated definitions of biodiversity than that of the CBD, conceptualizing its components in order to empower students to decide on current socioscientific issues.