Organisms of many species are specialized into male and female
varieties each known as a sex.[1][2] Sexual reproduction involves
the combining and mixing of genetic traits: specialized cells known
as gametes combine to form offspring that inherit traits from each
parent. The gametes produced by an organism define its sex: males
produce small gametes (e.g. spermatozoa or sperm in animals) while
females produce large gametes (ova or egg cells). Individual
organisms which produce both male and female gametes are termed
hermaphroditic.[2] Gametes can be identical in form and function
(known as isogamy) but in many cases an asymmetry has evolved such
that two different types of gametes (heterogametes) exist (known as
anisogamy).
Physical differences are often associated with the different sexes of an organism; these sexual dimorphisms can reflect the different reproductive pressures the sexes experience. For instance mate choice and sexual selection can accelerate the evolution of physical differences between the sexes.
Among humans and other mammals males typically carry an X and a Y chromosome (XY) whereas females typically carry two X chromosomes (XX) which are a part of the XY sex-determination system. Humans may also be intersex. Other animals have various sex-determination systems such as the ZW system in birds the X0 system in insects and various environmental systems for example in reptiles and crustaceans. Fungi may also have more complex allelic mating systems with sexes not accurately described as male female or hermaphroditic.
This app is about history and for research Purpose .
Physical differences are often associated with the different sexes of an organism; these sexual dimorphisms can reflect the different reproductive pressures the sexes experience. For instance mate choice and sexual selection can accelerate the evolution of physical differences between the sexes.
Among humans and other mammals males typically carry an X and a Y chromosome (XY) whereas females typically carry two X chromosomes (XX) which are a part of the XY sex-determination system. Humans may also be intersex. Other animals have various sex-determination systems such as the ZW system in birds the X0 system in insects and various environmental systems for example in reptiles and crustaceans. Fungi may also have more complex allelic mating systems with sexes not accurately described as male female or hermaphroditic.
This app is about history and for research Purpose .
Show More >