heat definition In physics, a form of energy associated with the movement of atoms and molecules in any material. The higher the temperature of a material, the faster the atoms are moving, and hence the greater the amount of energy present as heat.
Cilia (singular: cilium) are microscopic, hair-like structures that extend outwardfrom the surface of manyanimal cells. These structures are important in the cell cycle and replication, and cilia play a vital part in human and animal development and in everyday life. A typical cilium is between one and ten micrometers long, and usually less than one micrometer wide.
Flagella and Cilia. Flagella and cilia are hairlike structures,made primarily of protein, found on the surfaces of cells and used for movement by microorganisms and some specialized cells, such as the gametes of certain plants with motile sperm.