Organic Matter: Carbon (C) is what makes something organic; if it doesn't contain carbon, then it is not a living thing. For this reason, carbon is often considered the element of life.
Photosynthesis: Carbon is part of the compound Carbon Dioxide (CO2), and CO2 is a reactant in the process known as photosynthesis.
Cellular respiration: Although similar to photosynthesis, cellular respiration contains CO2 as a product, not a reactant, as is the case with photosynthesis.
