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Chromosomes are passed on from one generation to the next in this process.Each cell in the offspring has half the chromosomes of the mother and half of the father.the origin of chromosomal sex determination may have been fairly early in eukaryotes (see evolution of anisogamy).
Sexual reproduction is a process specific to eukaryotes, organisms whose cells contain a nucleus and mitochondria.
Disregarding intermediates, the basic distinction between asexual and sexual reproduction is the way in which the genetic material is processed.
Typically, prior to an asexual division, a cell duplicates its genetic information content, and then divides. In sexual reproduction, there are special kinds of cells that divide without prior duplication of its genetic material, in a process named meiosis.
XY sex determination is used by most mammals, The X0 sex-determination is found in most arachnids, insects such as silverfish (Apterygota), dragonflies (Paleoptera) and grasshoppers (Exopterygota), and some nematodes, crustaceans, and gastropods.
and from a comparison between chicken and human, the Z chromosome appeared similar to the autosomal chromosome 9 in human, rather than X or Y, suggesting that the ZW and XY sex-determination systems do not share an origin, but that the sex chromosomes are derived from autosomal chromosomes of the common ancestor of birds and mammals.