Aerobic Respiration

Big quiz in about two hours. Please keep it short and simple. Two more questions: Why is lactic acid fermentation important to the cell when oxygen is scarce? & How many ATP molecules are produced after the electrons go down the electron transport chain?

When sugar is burned, carbon dioxide and water are produced. What happens to the water that our body produces from aerobic respiration? Does it get sent into our system the same way it would if we drank a glass of water? Thanks.