APES Objectives – Unit 1

Summary

Unit 1, titled “The Living World: Ecosystems,” focuses on foundational ecological concepts. It covers how resource availability influences species interactions like competition and symbiosis. The unit also describes the global distribution and characteristics of both terrestrial and aquatic biomes. A significant portion of the unit is dedicated to explaining the steps and reservoir interactions of major biogeochemical cycles, specifically the carbon, nitrogen, phosphorus, and hydrologic cycles. Finally, it explores concepts of primary productivity, trophic levels, and the flow of energy through ecosystems, including the 10% rule and the use of food webs. This unit is estimated to make up 6-8% of the AP Exam.