The ultimate source of energy is the sun, and the portal through which this life force flows into the biosphere is carried out by green plants. As a result, all organisms—plants, animals, and microbes—use photosynthetic energy for their own needs. Photosynthesis and Respiration, Second Edition introduces the concept of plants as photosynthetic machines and follows the flow of energy and carbon through the natural processes of photosynthesis and respiration. The interaction between photosynthesis and the environment is explored throughout this volume, as well as the role that plants play in balancing the global carbon budget. This reference is a vital tool for students and teachers of biological processes.