This AP Environmental Science (APES) exam study and review pack (print & digital versions included) covers all 9 College Board units — ecosystems, biodiversity, populations, earth systems, land and water use, energy resources, atmospheric pollution, aquatic and terrestrial pollution, and global change. Every major concept, equation, and real-world case study is explained and practiced. This study guide includes a 100-question practice test, answer key with explanations, a 10-case-study reference