Answer:
The third step in cellular respiration is the citric acid cycle, also known as the Krebs cycle. In this step, the products of glycolysis are broken down further to produce carbon dioxide, NADH, and FADH2. The NADH and FADH2 then enter the electron transport chain, where they are used to produce ATP. The carbon dioxide is released as a waste product. This step is crucial for the production of ATP, the energy currency of the cell. It is also a highly efficient process, as it produces a large amount of ATP for every molecule of glucose that is broken down.