Book excerpt: NOTE: This edition features the same content as the traditional text in a convenient, three-hole-punched, loose-leaf version. Books a la Carte also offer a great value--this format costs significantly less than a new textbook. The Eleventh Edition of the best-selling text Campbell BIOLOGY sets you on the path to success in biology through its clear and engaging narrative, superior skills instruction, and innovative use of art, photos, and fully integrated media resources to enhance teaching and learning. To engage you in developing a deeper understanding of biology, the Eleventh Edition challenges you to apply knowledge and skills to a variety of NEW! hands-on activities and exercises in the text and online. NEW! Problem-Solving Exercises challenge you to apply scientific skills and interpret data in the context of solving a real-world problem. NEW! Visualizing Figures and Visual Skills Questions provide practice interpreting and creating visual representations in biology. NEW! Content updates throughout the text reflect rapidly evolving research in the fields of genomics, gene editing technology (CRISPR), microbiomes, the impacts of climate change across the biological hierarchy, and more. Significant revisions have been made to Unit 8, Ecology, including a deeper integration of evolutionary principles. NEW! A virtual layer to the print text incorporates media references into the printed text to direct you towards content in the Study Area and eText that will help you prepare for class and succeed in exams--Videos, Animations, Get Ready for This Chapter, Figure Walkthroughs, Vocabulary Self-Quizzes, Practice Tests, MP3 Tutors, and Interviews. (Coming summer 2017). NEW! QR codes and URLs within the Chapter Review provide easy access to Vocabulary Self-Quizzes and Practice Tests for each chapter that can be used on smartphones, tablets, and computers.