Reproduction

Reproduction (or procreation or breeding) is the biological process by which new individual organisms – offspring – are produced from their parent or parents. There are two forms of reproduction: asexual and sexual. In asexual reproduction, an organism can reproduce without the involvement of another organism. Asexual reproduction is not limited to single-celled organisms. The cloning of an organism is a form of asexual reproduction. By asexual reproduction, an organism creates a genetically similar or identical copy of itself. The evolution of sexual reproduction is a major puzzle for biologists. The two-fold cost of sexual reproduction is that only 50% of organisms reproduce, and organisms only pass on 50% of their genes. Sexual reproduction typically requires the sexual interaction of two specialized reproductive cells, called gametes, which contain half the number of chromosomes of somatic cells and are created by meiosis, with typically a sperm cell fertilizing an egg cell of the same species to create a fertilized zygote. This produces offspring organisms whose genetic characteristics are derived from both parental organisms.