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.
When plants and animals die, the organic compounds in them break down or decay. The carbon leaves their decaying bodies as carbon dioxide. Carbon dioxide is also released when anything organic burns. Instruct students to use the handout Diagram of the Carbon-Oxygen Cycle and write an essay describing the process. Students are to follow the arrows to explain what is involved in this cycle.