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.
Energy and Metabolism. All living organisms need energy to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is the set of life-sustaining chemical processes that enables organisms transform the chemical energy stored in molecules into energy that can be used for cellular processes.
Living things use energy within their cells. This energy powers all kinds of processes, such as reproduction, growth, or body temperature regulation. Some living things take in nutrients, such as eating food or absorbing materials through roots or a cell membrane. Other living things get energy from the sun.