A fatty acid is if it contains no carbon-carbon double bonds, if it has only one carbon-carbon double bond, and if it contains two or more carbon-carbon double bonds.

A fatty acid is saturated if it contains no carbon-carbon double bonds, monounsaturated if it has only one carbon-carbon double bond, and polyunsaturated if it contains two or more carbon-carbon double bonds.

Explanation: Fatty acids are compounds found in both plants and animals that contain long chains of carbon. The oxidation of fatty acids to acetyl CoA is a central energy-yielding pathway in animals. Fatty acids can be classified as saturated and unsaturated. A fatty acid is said to be saturated if it contains only single bonds in its carbon chain. A fatty acid is said to be unsaturated if it contains one or more double bonds in its carbon chain. An unsaturated fatty acid can be monounsaturated or polyunsaturated, when a fatty acid contains only one double bond in its carbon chain it is monounsaturated but when a fatty acid contains more than one double bond in its carbon chain, it is polyunsaturated.

atp is used for energy.