When an egg or sperm with an abnormal number of chromosomes is joined with a normal egg or sperm, then the resulting fertilized cell will not have 46 chromosomes. This is referred to as aneuploidy. Down syndrome and Turner’s syndrome are examples of aneuploidy. Polyploidy is common in plants, and plant growers may exploit this fact to produce plants with flowers having double petals. Polyploidy is generally lethal in animals.
Aneuploidy is the presence of an abnormal number of chromosomes in a cell. There is an extra chromosome present in this case. Polyploidy is the presence of the extra set of the chromosome in the cells. There is a complete new set of the chromosome present.