The source of most variations come from

The random genetic combinations during chromosome crossover during meiosis

The sources of genetic variations is mutation

Various mutations are the ultimate source of genetic variations. Mutations are likely to be rare and most mutations are neutral or deleterious. There are several sources of variations but the two main sources of genetic variation are mutations and re combinations of genes which takes place as a result of sexual reproduction. A mutation is a permanent change in the DNA within a gene.

organ system-an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.

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