Biology 2e is designed to cover the scope and sequence requirements of a typical two-semester biology course for science majors. The text provides comprehensive coverage of foundational research and core biology concepts through an evolutionary lens. Biology includes rich features that engage students in scientific inquiry, highlight careers in the biological sciences, and offer everyday applications. The book also includes various types of practice and homework questions that help students understand—and apply—key concepts. The 2nd edition has been revised to incorporate clearer, more current, and more dynamic explanations, while maintaining the same organization as the first edition. Art and illustrations have been substantially improved, and the textbook features additional assessments and related resources.

By the end of this section, you will be able to do the following:

Define species and describe how scientists identify species as different
Describe genetic variables that lead to speciation
Identify prezygotic and postzygotic reproductive barriers
Explain allopatric and sympatric speciation
Describe adaptive radiation

By the end of this section, you will be able to do the following:

Describe how a karyogram is created
Explain how nondisjunction leads to disorders in chromosome number
Compare disorders that aneuploidy causes
Describe how errors in chromosome structure occur through inversions and translocations

Only a few types of aneuploidy are compatible with life. Use this drop-down menu to understand more about common genetic disorders resulting from monoploidy and polyploidy, such as Down Syndrome. Learn features of the disorder, see how it is managed, and view pictures of children with the disorder.