Female
hideFemale (♀) is the sex of an organism, or a part of an organism, which produces mobile ova (egg cells). The ova are defined as the larger gametes in a heterogamous reproduction system, while the smaller, usually motile gamete, the spermatozoon, is produced by the male. A female individual cannot reproduce sexually without access to the gametes of a male (an exception is parthenogenesis). Some organisms can reproduce both sexually and asexually.
There is no single genetic mechanism behind sex differences in different species and the existence of two sexes seems to have evolved multiple times independently in different evolutionary lineages. Other than the defining difference in the type of gamete produced, differences between males and females in one lineage cannot always be predicted by differences in another. The concept is not limited to animals; egg cells are produced by chytrids, diatoms, water moulds and land plants, among others. In land plants, female and male designate not only the egg- and sperm-producing organisms and structures, but also the structures of the sporophytes that give rise to male and female plants.
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News tagged with females
Opposites attract: Monkeys choose mating partners with different genes
Nov 24, 2009 |
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The world's largest species of monkey 'chooses' mates with genes that are different from their own to guarantee healthy and strong offspring, according to a new research study.
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Nuclear science to fight sleeping sickness
Nov 27, 2009 |
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The International Atomic Energy Agency on Friday announced an agreement to help African nations battle the tsetse fly, the main carrier of parasites that causes sleeping sickness with its bites.
A RANK insider resolving the enigma of the fever chart
Nov 25, 2009 |
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Mammals have evolved a complex system for controlling bone remodeling. Babies require calcium for healthy bones and they obtain it from their mother's milk. Nursing mothers release calcium from their bones. Surprisingly, ...
Study Finds Eating Fruits and Vegetables Lowers Risks of Heart Disease
Nov 25, 2009 |
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(PhysOrg.com) -- A new study of adults aged 70 or older found that increased servings of fruits and vegetables were significantly associated with a decrease of cognitive impairment, and that those eating three or more servings ...
Plasma levels of GGT and ALB and their genetic correlations with cardiovascular risk factors
Nov 24, 2009 |
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Two indicators of liver function, Gamma-glutamyl transferase (GGT) and albumin (ALB) have been implicated in the pathogenesis of atherosclerosis. It is known that the variation in the plasma level of these liver related proteins ...
Gene mismatch influences success of bone marrow transplants
Nov 22, 2009 |
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A commonly inherited gene deletion can increase the likelihood of immune complications following bone marrow transplantation, an international team of researchers reports in the November 22 advance online issue of Nature Ge ...
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