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:

Explain how a circular pathway, such as the citric acid cycle, fundamentally differs from a linear biochemical pathway, such as glycolysis
Describe how pyruvate, the product of glycolysis, is prepared for entry into the citric acid cycle

An overview of cellular respiration and mitochondria.

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This comprehensive study guide covers the main terms and concepts needed for a unit on cellular respiration.

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This 14-minute video lesson presents an introduction to cellular respiration, glycolysis, the Kreb's Cycle, and the electron transport chain. [Biology playlist: Lesson 21 of 71].

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This 18-minute video lesson provides an overview of the Krebs or Citric Acid Cycle. [Biology playlist: Lesson 25 of 71].

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In this unit, students look at the components of cells and their functions and discover the controversy behind stem cell research. The first lesson focuses on the difference between prokaryotic and eukaryotic cells. In the second lesson, students learn about the basics of cellular respiration. They also learn about the application of cellular respiration to engineering and bioremediation. The third lesson continues students' education on cells in the human body and how (and why) engineers are involved in the research of stem cell behavior.

Cellular respiration is the process by which our bodies convert glucose from food into energy in the form of ATP (adenosine triphosphate). Start by exploring the ATP molecule in 3D, then use molecular models to take a step-by-step tour of the chemical reactants and products in the complex biological processes of glycolysis, the Krebs cycle, the Electron Transport Chain, and ATP synthesis. Follow atoms as they rearrange and become parts of other molecules and witness the production of high-energy ATP molecules.

In this lesson, students learn about the basics of cellular respiration. They also learn about the application of cellular respiration to engineering and bioremediation. And, students are introduced to the process of bioremediation and several examples of how bioremediation is used during the cleanup of environmental contaminants.

Illustrated tutorial describing the processes that occur in the Krebs cycle during cellular respiration. [5:57]

Explore the specific reactions that happen during the cellular respiration process.

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Explains oxidative phosphorylation, which is the fourth step of cellular respiration, and produces the most of the energy in cellular respiration.

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.