SC.912.L.18.9

1. SC.912.L.18.9 Bryan Sanchez Period 3

2. Photosynthesis • Photosynthesis is a process used by plants and other autotrophic organisms to convert light energy, normally from the sun, into chemical energy that can be used to fuel the organisms' activities. • Carbohydrates, such as sugars, are synthesized from carbon dioxide and water, "light," during this process. Oxygen is also released, mostly as a waste product. Most plants, most algae, and cyanobacteria perform the process of photosynthesis, and are called photoautotrophs. • Photosynthesis maintains atmospheric oxygen levels and supplies most of the energy necessary for all life on Earth, except for chemotrophs, which gain energy through oxidative chemical reactions.

3. Cellular respiration • Cellular respiration is the set of the metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products. • The reactions involved in respiration are catabolic reactions, which break large molecules into smaller ones, releasing energy in the process as they break high-energy bonds. Respiration is one of the key ways a cell gains useful energy to fuel cellular activity. Cellular respiration is considered an exothermic redox reaction. • The overall reaction is broken into many smaller ones when it occurs in the body, most of which are redox reactions themselves. Although technically, cellular respiration is a combustion reaction, it clearly does not resemble one when it occurs in a living cell.