Cellular respiration is used to make ATP, adenosine triphosphate, which provides the energy that the cells need to be able to carry out their functions in living cells. All cells carry out some form of cellular respiration, either aerobic or anaerobic. The cells that perform aerobic respiration need oxygen to carry out the process, while cells that use the anaerobic process do not, instead relying on fermentation.
In plants, energy is created through photosynthesis. This process uses sunlight processed through the chlorophyll of the plants to create the sugars needed for energy. Without this process the plants could not absorb carbon dioxide or produce oxygen that other living organisms need to live.