During respiration, carbon compounds are oxidized, and carbon combines with oxygen to produce carbon dioxide. As a result, carbon dioxide is released into the environment. During photosynthesis, green plants take water and carbon dioxide from the environment and use it to make organic compounds. In this process, water molecules are broken apart, and oxygen is released as a gas into the environment. Another part of the carbon-oxygen cycle involves the making of inorganic compounds.
Plants use carbon dioxide to make carbohydrates during photosynthesis.
The other organic compounds are made from these carbohydrates. Plant-eating animals use these organic compounds to make their own protoplasm. They, in turn, are eaten by other animals. These animals also use these compounds. All organic compounds contain carbon.