I can tell you're not very educated because everyone knows that breathing pure oxygen for long periods of time can sometimes hurt us. Oxygen in lower levels, such as levels found in atmosphere are just right for us to breathe. Get a life and stop trying to scare young kids that just want help on their homework.
Glycolysis--The breakdown of a glucose molecule into two three-carbon pieces called pyruvate. You will notice that very little ATP is produced in this step and no oxygen is required. ... This step is also where other molecules besides glucose may be fed into the cell respiration<span> process, especially lipids.</span>