Which stage of cellular respiration requires oxygen that you breathe?

The cellular respiration occurs in two main forms or mechanisms, the first one is the aerobic respiration which obviously takes place in the presence of the oxygen,O₂ molecule. While, the second takes place in the absence of the oxygen,O₂ molecules. For, the aerobic form of cellular respiration the oxygen is required to be present during the  process of  releasing the optimum amount of energy or executing of the whole process in a more proper way. As, the aerobic respiration is executed in the following three steps: Glycolysis.The Kreb's cycle.And the electron transport chain, to which the oxygen is mandatory or required.                                                                                              

I’m not exactly sure what your trying to ask, but if it’s how an organelle is similar to a body system or a part a nucleus is like a in function. but i don’t fully understand what you’re trying to ask