(mÄth'Än') A colorless, odorless, flammable gas that is the simplest hydrocarbon. It is the major constituent of natural gas and is released during the decomposition of plant or other organic compounds, as in marshes and coal mines. Methane is the first member of the alkane series.
In photosynthesis, solar energy is converted to chemical energy. The chemical energy is stored in the form of glucose (sugar). Carbon dioxide, water, and sunlight are used to produce glucose, oxygen, and water.
Photosynthesis is the plant process where light energy is used to generate the production of ATP. The ATP so formed is used to form the bonds between carbon dioxide molecules and hydrogen atoms released from water by the light energy. The process forms sugar (glucose) molecules and produces oxygen as a waste product. At a glance, the equations: sugar + oxygen --> carbon dioxide + water + ATP energy (cellular respiration) and carbon dioxide + water + sun's energy --> sugar + oxygen (photosynthesis) look to be the reverse of each other.