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:

Compare homologous and analogous traits
Discuss the purpose of cladistics
Describe maximum parsimony

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

Discuss the need for a comprehensive classification system
List the different levels of the taxonomic classification system
Describe how systematics and taxonomy relate to phylogeny
Discuss a phylogenetic tree's components and purpose

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

Describe horizontal gene transfer
Illustrate how prokaryotes and eukaryotes transfer genes horizontally
Identify the web and ring models of phylogenetic relationships and describe how they differ from the original phylogenetic tree concept

This 13-minute video lesson looks at the science of taxonomy and where humans fit into the tree of life. [Biology playlist: Lesson 62 of 71].

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

CK-12’s Life Science delivers a full course of study in the life sciences for the middle school student, relating an understanding of the history, disciplines, tools, and modern techniques of science to the exploration of cell biology, genetics, evolution, prokaryotes, protists, fungi, plants, the animal kingdom, the human body, and ecology. This digital textbook was reviewed for its alignment with California content standards.

This is a very good introduction to the role evolution plays in the development of biodiversity. These topics and extinction are explained with the use of colorful interactive pictures.

See how scientists trace species through their evolutionary relationships.

A free CK-12 account is required to view all materials.

Learn about the diversity of species on Earth by exploring a cladogram, a graph-like tree of life that illustrates relatedness among species. Includes instructions for reading cladograms and a pie chart that summarizes the percentages of the world's living things that belong to select classifications.

Some vertebrates have fins and some have limbs with digits to move across land. Discover these creatures with limbs and digits from who they are to who they were and how they evolved.

Learn how to read and draw phylogenetic trees, or cladograms. [10:57]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.