In sexual reproduction, a daughter cell obtains the genetic material from two different parents and hence the genetic diversity. In comparison, in asexual reproduction, an individual just grows and splits, resulting in a daughter cell which is an exact replica of parent cell. Sexual reproduction uses the process of meiosis, in which the genetic material of each cell doubles and the cell itself divides into four new cells or gametes. Each of these gametes has only half the genetic material of the parent cell and must fuse with another gamete, in order to produce a new organism. During meiosis, the process of crossing over takes place, in which homologous chromosomes (in the cell) pair up and exchange parts with each other. Since they originally came from different parents (2 different individuals), crossing over increases the diversity. These crossed-over chromosomes go into different gametes (through individual assortment) and two different gametes (containing different combination of genetic material) must fuse to produce a new organism. This is how sexual reproduction increases genetic variation.
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