Two parents are needed in sexual reproduction. During this process the nuclei of the male and female gametes are fused in order to create a zygote. This process is known as fertilisation. The gametes contain half the number of chromosomes (they are haploid). When the male and female gametes combine, they create the full complement of chromosomes (they are now diploid) in order to create a human embryo.

Gametes are formed by a type of cell division called meiosis.

The gametes in:

  • animals are sperm and eggs
  • flowering plants are pollen and eggs


In meiosis:

  1. copies of the genetic information are made
  2. the cell divides twice to form four gametes, each with a single set of chromosomes (haploid)
  3. all gametes are genetically different from each other, they show variation
A diagram illustrating the process of meiosis and how it creates gametes

The cells formed in meiosis are all genetically different. This is because the chromosomes - and genes - separate and are reshuffled during the process.

Produces genetically identical daughter cellsProduces genetically varied daughter cells
Daughter cells have a full set of chromosomes (diploid)Daughter cells have half a set of chromosomes (haploid)
2 daughter cells are produced4 daughter cells are produced
Occurs in all body cells except gamete forming cellsOnly occurs in gamete forming cells
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