Carbon is one of the basic building blocks of all life in the universe.
Carbon dioxide in the atmosphere and water form the main reserves of carbon. In the process of photosynthesis, green plants use carbon dioxide from the air and water from the soil. Through a series of chemical rearrangements, the plants turn these raw materials into organic compounds called carbohydrates. These carbohydrates are composed largely of carbon and hydrogen atoms. When a green plant dies, these organic compounds are broken down by bacteria and other decomposers.