Answer:
Carbondioxide gas used by plants in photosynthesis and these plants are eaten by animals. During respiration, this carbondioxide again released in the atmosphere.
Explanation: Carbondioxide ia a raw material which is used by the plants in the process of photosynthesis. This carbondioxide react with water and make food from it. This food which contains carbon is eaten by herbivores. The food is used by the mitochondria of the cell to generate energy in the process of respiration. In this process carbondioxide is released in the atmosphere and the cycle is repeated again and again.