We can show the possible reactions of any substance in a cell in a diagram ... and is used in the process of respiration. All cells require glucose for respiration. Animals can convert glycogen ...

oxygen is not necessary for anaerobic respiration to take place. In micro-organisms such as yeast, a uni-cellular (or single cell) fungi, the process of anaerobic respiration is called fermentation.

This process requires specialized organs such as the lungs or gills. This oxygen is used for cellular respiration and metabolism, a byproduct of which is carbon dioxide.