Diploidy and Haploidy :: In the chromosomal complement  given species  not all the  chromosomes are different  from each other .In fact these  are in pairs ,i.e.  every  two chromosomes of the  karyotype  are similar  in shapes  size and  structure or say  are homologous, Obviously  the chromosomes   of one pairs  are different from  those of every  other pair. This  means  that the karyotype in fact  comprises two  similar sets of chromosomes, Hence it  is called diploid )2x or 2n,)

In sexual reproduction ,union of two  different  sex cells  or gametes  (male gamete or sperm cell and  female gamete or ovum) occur  to form a single diploid  cell called  zygote. From  the zygote, all body  cells  of a new  individual  arise by  repeated   mitotic divisions. Thus the karyotypic diploid chromosomal  complement  is transmitted  to all  body  cells. However  to prevent   multiplication  of the diploid  complement the sex  cells must contain  only half  the number  or say a single  set or chromosomes .This gametic chromosomal complement is thus, haploid (x or n) and  called genome, in contrast  to the  karyotype  of diploid  somatic cells, Obviously  of the  two sets  of chromosomal in a karyotype in every  individual, one is originally  obtained from male and the  other female parents.