how would you respond to this post. ATP yield in aerobic respiration is only a theoretical number because cells have other jobs, not just making ATP. The other jobs cells have which require the use of energy is moving nutrients and powering other parts of the cell. Another example that changes the theoretical number is in eukaryotes, this is when more energy is needed to move certain molecules into the mitochondria. The textbook gives a range of 36-38 ATP per glucose, which in reality that number is usually lower. Those numbers are assuming no energy is lost. Realistically the number is between 30-32 ATP because there's always energy used in other ways or is wasted