An atom is the smallest component of an element that still retains the properties of the element.

Convection is the transfer of heat by the circulation or movement of the heated parts of a liquid or gas. Examples of heat transfer by convection include water coming to a boil on a stove, ice melting, and steam from a cup of coffee.

Decomposers (saprotrophs) are organisms such as bacteria and fungi that break down the organic matter in the dead bodies of plants and animals into simple nutrients.

Force is applied to change an object's speed or direction of motion.

Food is mixed with gastric acid and pepsin in the stomach to help break down protein.