These carbon compounds are broken down inside the cell in a controlled manner to release the stored chemical energy for utilization in various cellular functions. This process is known as respiration or, more specifically, ccllular respiration. Cellular respiration is an oxidation process where the energy released is conserved as the high energy terminal bonds of ATP that can be readily utilized by the cell to do work.
The step by step reactions of respiration also modify the carbohydrates to form the carbon skeletons that make up the basic building blocks of cell structure.
The overall process of respiration and photosynthesis appears as reverse metabolic processes and certain commonalities do exist between these processes. A comparative account of some aspects of photosynthesis and respiration are given in Box I.