Sexually reproducing organisms

Sexually reproducing organisms transmit their genes in the form of haploid gametes (ova and sperm, or pollen) formed by meiosis. This reductive cell division halves the chromosome number so the diploid number of chromosomes can be regenerated on fertilisation. Meiosis introduces variation through crossing over and independent segregation of chromosomes, and random fusion ensures further variety in the offspring produced. In this way the genetic information is transmitted from generation to generation introducing a diverse range of alleles that adds not only variety, but helps ensure a population can survive and adapt to any environmental changes