Polyploidy is the cause of Down's syndrome. Tay Sachs disease is found mostly in Jewish people. Sickle cell anemia is found mostly in persons of negroid origin. Most mutations are recessive and beneficial. Mutations are sources of variations in offspring.
Mutations occur in only fruit flies and molds.
Mutations can not occur unless the mutating cell is exposed to ionizing radiation. The unzipping of a double stranded molecule. The formation of hydrogen bonds. The synthesis of ribosomes. The breaking of hydrogen bonds.