Biology challenges students to explore concepts that explain living systems. Themes that undergird units of study include living systems in balance, and the return of systems impacted by internal and external forces to new states of balance. Units of study include ecology, cell biology, comparative anatomy of invertebrates, and genetics and evolution. Students practice scientific process skills such as proper procedures to generate and analyze data so that results help support concepts. Issues investigated in Biology include the challenges of genetic engineering as well as the threats to biodiversity and to the health of local communities on account of invasive species and habitat loss.