Cold sores - painful sores on the lips and around the mouth, caused by a virus. Canker sores - painful sores in the mouth, caused by bacteria or viruses. Thrush - a yeast infection that causes white patches in your mouth. Leukoplakia - white patches of excess cell growth on the cheeks, gums or tongue, common in smokers.
Metabolism is a combination of chemical reactions that are spontaneous and release energy and chemical reactions that are non-spontaneous and require energy in order to proceed. Living organisms must take in energy via food, nutrients, or sunlight in order to carry out cellular processes.
Energy is defined as the ability to do work. Cellular respiration provides energy for living organisms. So, cellular respiration is important because it provides the energy for living organisms to perform all of the other necessary functions to maintain life. Most single-celled organisms, such as bacteria, do not require much energy and are able to survive on glycolysis and fermentation.