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The Scientific Miracles Of The Holy Quran 12 (The Sex Of A Baby)

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Uploaded on Jun 9, 2009

Islam Is The Only TRUTH

Gender comprises a range of differences between men and women, extending from the biological to the social. At the biological level, men and women are typically distinguished by the presence of a Y-chromosome in male cells, and its absence in female cells. At the social level, however, there is debate regarding the extent to which the various biological differences necessitate differences in social gender roles and gender identity, which has been defined as "an individual's self-conception as being male or female, as distinguished from actual biological sex."[ Historically, feminism has posited that many gender roles are primarily socially constructed, offering explanations in terms of unequal economic and other power relations, rather than in biology.
Although "gender" is popularly used interchangeably with "sex" (properly denoting male or female biology), or more recently with "sexual orientation" and "identity" (especially LGBT sexuality), historically, within the social sciences, including political economy, it refers to specifically social differences.[3] People whose gender identity feels incongruent with their biological sex may refer to themselves as "intergender".
Many languages have a system of grammatical gender, a type of noun class system—nouns may be classified as masculine or feminine (for example Spanish, Hebrew, Arabic and French) and may also have a neuter grammatical gender (for example Sanskrit, German, Polish, and the Scandinavian languages). In such languages, this is essentially a convention, which may have little or no connection to the meaning of the words. Likewise, a wide variety of phenomena have characteristics termed gender, by analogy with male and female bodies (such as the gender of connectors and fasteners) or due to societal norms. Sexual reproduction is a common method of producing a new individual within various species. In sexually reproducing species, individuals produce special kinds of cells (called gametes) whose function is specifically to fuse with one unlike gamete and thereby to form a new individual. This fusion of two unlike gametes is called fertilization. By convention, where one type of gamete cell is physically larger than the other, it is associated with female sex. Thus an individual that produces exclusively large gametes (ova in humans) is said to be female, and one that produces exclusively small gametes (spermatozoa in humans) is said to be male.An individual that produces both types of gametes is called hermaphrodite (a name applicable also to people with one testis and one ovary). In some species hermaphrodites can self-fertilize (see Selfing), in others they can achieve fertilization with females, males or both. Some species, like the Japanese Ash, Fraxinus lanuginosa, only have males and hermaphrodites, a rare reproductive system called androdioecy. Gynodioecy is also found in several species. Human hermaphrodites are typically, but not always, infertile.
What is considered defining of sexual reproduction is the difference between the gametes and the binary nature of fertilization. Multiplicity of gamete types within a species would still be considered a form of sexual reproduction. However, of more than 1.5 million living species, recorded up to about the year 2000, "no third sex cell — and so no third sex — has appeared in multicellular animals." Why sexual reproduction has an exclusively binary gamete system is not yet known. A few rare species that push the boundaries of the definitions are the subject of active research for light they may shed on the mechanisms of the evolution of sex. For example, the most toxic insect,[24] the harvester ant Pogonomyrmex, has two kinds of female and two kinds of male. One hypothesis is that the species is a hybrid, evolved from two closely related preceding species.
Fossil records indicate that sexual reproduction has been occurring for at least one billion years.[25] However, the reason for the initial evolution of sex, and the reason it has survived to the present are still matters of debate, there are many plausible theories. It appears that the ability to reproduce sexually has evolved independently in various species on many occasions. There are cases where it has also been lost, notably among the Fungi Imperfecti.[26] The blacktip shark (Carcharhinus limbatus), flatworm (Dugesia tigrina) and some other species can reproduce either sexually or asexually depending on various conditions

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