Sexual reproduction includes syngamy and meiosis. Syngamy is the nuclear fusion of male and female gamete. The meiosis is the reduction of chromosome number to haploid during meiosis genetic recombination occurred as a result of crossing over. The presence of more than two set of chromosome (genomes) is called polyploidy, eg, hexaploid wheat (6x). The term euploidy designates genomes containing chromosomes that are multiples of same basic number (x). It includes monoploid and polyploid. Aneuploidy involve a change in part of chromosome set of individuals. It includes hypoploidy and hyperploidy.