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 “energy”
Explain the difference between kinetic and potential energy
Discuss the concepts of free energy and activation energy
Describe endergonic and exergonic reactions

In the following video, Paul Andersen explains how energy can neither be created nor destroyed but may be transferred. Energy comes in many forms. [4:09]

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.

The students participate in many demonstrations during the first day of this lesson to learn basic concepts related to the forms and states of energy. This knowledge is then applied the second day as they assess various everyday objects to determine what forms of energy are transformed to accomplish the object's intended task. The students use block diagrams to illustrate the form and state of energy flowing into and out of the process.

Demonstrations explain the concepts of energy forms (sound, chemical, radiant [light], electrical, atomic [nuclear], mechanical, thermal [heat]) and states (potential, kinetic).

Students learn about kinetic and potential energy, including various types of potential energy: chemical, gravitational, elastic and thermal energy. They identify everyday examples of these energy types, as well as the mechanism of corresponding energy transfers. They learn that energy can be neither created nor destroyed and that relationships exist between a moving object's mass and velocity. Further, the concept that energy can be neither created nor destroyed is reinforced, as students see the pervasiveness of energy transfer among its many different forms. A PowerPoint(TM) presentation and post-quiz are provided.

Students play the role of engineers as they test, design and build Mentos(TM) fountains a dramatic example of how potential energy (stored energy) can be converted to kinetic energy (motion). They are challenged to work together as a class to optimize the design of the basic soda/candy geyser made by the teacher. To do this, three research teams each investigate how a different variable nozzle shape, soda temperature, number of candies affects fountain height. They devise and run experimental tests to determine the best variable values. Then they combine their results to design the highest fountain to compete head-to-head with the teacher's geyser design.

Students explore how energy is transferred and how it can be converted into different forms, and learn about renewable and nonrenewable energy while looking towards the world’s energy future.

Through this lab, students are introduced to energy sciences as they explore redox reactions and how hydrogen fuel cells turn the energy released when hydrogen and oxygen are combined into electrical energy that can be read on a standard multimeter. They learn about the energy stored in bonds and how, by controlling the reaction, this energy can be turned into more or less useful forms.

Students are introduced to statics and dynamics, free-body diagrams, combustion and thermodynamics to gain an understanding of the forces needed to lift rockets off the ground. They learn that thrust force is needed to launch rockets into space and the energy for thrust is stored as chemical energy in the rocket's fuel. Then, using the law of conservation of energy, students learn that the chemical energy of the fuel is converted into work and heat energy during a rocket launch. A short PowerPoint® presentation is provided, including two example problems for stoichiometry review. An optional teacher demonstration is described as an extension activity.

Building on an introduction to statics, dynamics free-body diagrams, combustion and thermodynamics provided by the associated lesson, students design, construct and test their own rocket engines using sugar and potassium nitrate an opportunity to apply their knowledge of stoichiometry. This activity helps students understand that the energy required to launch a rocket comes from the chemical energy stored in the rocket fuel. The performance of each engine is tested during a rocket launch, after which students determine the reasons for the success or failure of their rockets.

Three short, hands-on, in-class demos expand students' understand of energy. First, using peanuts and heat, students see how the human body burns food to make energy. Then, students create paper snake mobiles to explore how heat energy can cause motion. Finally, students determine the effect that heat energy from the sun (or a lamp) has on temperature by placing pans of water in different locations.

With an introduction to the ideas of energy, students discuss specific types of energy and the practical sources of energy. Hands-on activities help them identify types of energy in their surroundings and enhance their understanding of energy.