It's because today I had science and we learned a new subject which is cellular respiration.
I'm going to explain
Is the breakdown of organic molecules, is for satisfy our self by littlepieces of food (glucose) and transform the food to ATP (energy).And the process is like this: first the glucosse (food) past to be Glycolysis and the glycolysis Break the sugar and transform to 2 pyruvate that divide, why? because if oxygen is available happen in the mitochondria and produce 6 molecules of water (H2O), oxigen (O2) and carbon (CO2)dioxide, also 32 molecules of ATP (energy). But if oxygen is not available past to be fermentation and this happen in the cytosol or cytoplasm and produce 2 molecules of lactate and ATP .