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 matter and elements
Describe the interrelationship between protons, neutrons, and electrons
Compare the ways in which electrons can be donated or shared between atoms
Explain the ways in which naturally occurring elements combine to create molecules, cells, tissues, organ systems, and organisms

A video lesson which illustrates how to identify and complete a synthesis chemical reaction. [8:08]

Chemical reactions are the foundation of chemistry, and understanding how elements combine and in what ratios helps us to understand the world around us. This pathway provides resources about how different chemicals react, and the ratios in which they react, a field of study known as Stoichiometry (literally: element measuring).

Students create silver nanoparticles using a chemical process; however, since these particles are not observable to the naked eye, they use empirical evidence and reasoning to discover them. Students first look for evidence of a chemical reaction by mixing various solutions and observing any reactions that may occur. Students discover that copper and tannic acids from tea reduce silver nitrate, which in turn form silver. They complete the reaction, allow the water to evaporate, and observe the silver nanoparticles they created in plastic dishes using a stereo microscope. Students iterate on their initial process and test to see if they can improve the manufacturing process of silver nanoparticles.

When a chemcial reaction occurs in a closed system, it will reach an equilibrium state in which reactants and products are produced at the same rate. This pathway provides resources to undestand the factors that affect chemical equilibrium.

Students investigate the endothermic reaction involving citric acid, sodium bicarbonate and water to produce carbon dioxide, water and sodium citrate. In the presence of water [H2O], citric acid [C6H8O7] and sodium bicarbonate [NaHCO3] (also known as baking soda) react to form sodium citrate [Na3C6H5O7], water [H2O], and carbon dioxide [CO2]. Students test a stoichiometric version of the reaction followed by testing various perturbations on the stoichiometric version in which each reactant (citric acid, sodium bicarbonate, and water) is strategically doubled or halved to create a matrix of the effect on the reaction. By analyzing the test matrix data, they determine the optimum quantities to use in their own production companies to minimize material cost and maximize CO2 production. They use their test data to "scale-up" the system from a quart-sized ziplock bag to a reaction tank equal to the volume of their classroom. They collect data on reaction temperature and CO2 production.