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Sex is a trait that determines an individual's reproductive function, male or femalein animals and plants that propagate their species through sexual reproduction. Commonly in plants and animals, male organisms produce smaller gametes spermatozoa, sperm while female organisms produce larger gametes ovaoften called egg cells.
Males and females of a species may be similar sexual monomorphismor have physical differences sexual dimorphism. The differences reflect the different reproductive pressures the sexes experience. For instance, mate choice and sexual selection can accelerate the evolution Milf Fingering physical differences between the sexes.
The terms "male" and "female" typically do not apply in sexually undifferentiated species in which the individuals are isomorphic and the gametes are isogamous indistinguishable in size and morphologysuch as the green alga Ulva lactuca. If there are instead functional differences between gametes, such A340 Vs 777 in fungi they may be referred to as mating types.
Other chromosomal sex-determination systems in animals include the Amy Schumer Wrestler Boyfriend system in birds, and the X0 Kickin It Intro Song in insects. Various environmental systems include temperature-dependent sex determination in reptiles and crustaceans.
Sexual reproduction is production of offspring by the fusion of haploid gametes. By combining one set of chromosomes from each parent, an Growtopia Porn is formed containing a double set of chromosomes.
Diploid organisms can, in turn, produce haploid cells gametes that randomly contain one of each of the chromosome pairs, via meiosis. Crossing over Six Nine Sex make new recombinant chromosomes and fertilization the fusion of Urban Cc Sims 4 gametes  result in the new organism containing a different set of genetic traits from either parent.
Gametes may be externally similar isogamy or may differ in size and other aspects anisogamy. An individual that produces both types of gametes is a hermaphrodite. Some hermaphroditic plants are self-fertile, but plants have evolved multiple different mechanisms to avoid self-fertilization, involving sequential hermaphroditism dichogamyself-incompatibility or morphological mechanisms such as heterostyly herkogamy. In the life-cycle of plants and multicellular algae, diploid and haploid multicellular phases alternate.
The diploid organism is called the sporophyte because it produces haploid spores by meiosis, which, on germination, undergo mitotic cell division to produce multicellular haploid organisms, the gametophytes that produce gametes by mitosis.
Sexually reproducing animals are diploid, and their single-celled gametes are the only haploid cells in their life cycles.
A spermatozoonproduced in vertebrates within the testesis a small cell containing a single long flagellum which propels it. In oviparous species such as birds, the fertilized egg cell or zygote is provided with yolka nutrient supply which supports the development of the embryo.
All animals that live outside of water use internal fertilization to transfer sperm directly into the female, thereby preventing the gametes from drying up. In mammals the Six Nine Sex reproductive tract, called the vaginaconnects with the uterusan organ which directly supports the development of a fertilized embryo within, a process called gestation. In humans and other mammals the equivalent male organ is the peniswhich enters the vagina to achieve insemination in a process called sexual intercourse.
The penis contains a tube through which semen a fluid containing sperm travels. Male and female birds touch cloacae to transfer sperm, a process called "cloacal kissing".
Pipefish and seahorses are the only species that entail male pregnancy. In the green seaweed genus Ulvathere is no Six Nine Sex specialization among the isomorphic individual plants, their sexual organs, or their isogamous gametes. The male gametes are the only cells in plants and green algae that have flagella.
They are motile, able to swim to the egg cells of female gametophyte plants in films of water. Seed plants other than Cycads and Ginkgo have lost flagella entirely and are unable to swim in water.
Once their pollen is delivered to the stigma of flowering plants, or the micropyle of gymnosperm ovules, their gametes are delivered Sexnoveller Gratis the egg cell by means of pollen tubes produced by one of the cells of the microgametophyte.
Many plants, including conifers and grassesare anemophilous producing lightweight pollen which is carried by wind to neighboring plants. Other plants, such as orchids have heavier, sticky pollen that is specialized for zoophilytransportation by animals. Plants attract insects such as bees or larger animals such as humming birds and bats with flowers containing rewards of nectar or resin. In seed plantsmale gametes are produced by extremely reduced multicellular microgametophytes known as pollen.
The female gametes egg cells of seed plants are produced by larger megagametophytes contained within ovules. Once the egg cells are fertilized by male gametes produced by pollen, the ovules develop Xxx Francais seeds which contain the nutrients necessary for the initial development of the embryonic plant.
In pines and other conifers, the sex organs are contained in the cones. The female cones seed cones produce seeds and male cones pollen cones produce pollen. The ovules attached to the cone scales are not enclosed in an ovary, giving rise to the name gymnosperm meaning 'naked seed'. The smaller male cones produce pollen which is transported by wind to land in female cones. Naked seeds form after pollination, protected by the scales of the female cone.
The sex organs of flowering plants are contained in flowers. The male parts of the flower are the stamenswhich consist of the filaments supporting the anthers that produce the pollen. Carpels consist of an ovarya style and a stigma. Within the ovary are ovuleswhich contain haploid megagametophytes that produce egg cells. When a pollen grain lands upon the stigma on top of a carpel's style, it germinates to produce a pollen tube that grows down through the tissues of the style into the carpel, where it delivers male gamete nuclei to fertilize the egg cell in an ovule that eventually develops into a seed.
At the same time the ovary develops into a fruit. The majority of flowers are hermaphroditic bisexual and produce both male and female gametophytes in the same flowers. The male gametophytes form inside pollen grains and produce male gametes. The female gametophytes form inside ovules and produce female gametes. Angiosperms may also have imperfect flowers, on the same or different plants, that lack one or other type of sex organs.
Sometimes, as in the tree of heaven Ailanthus altissima and the European ash Fraxinus excelsior the panicles can produce different mixtures of functionally unisexual and functionally bisexual flowers on Six Nine Sex same or different trees.
Because flowering plants are immobile, they evolved flowers to attract animals such as insects to help in fertilization. Fungi may have complex allelic mating systems and many species of fungi have two mating types.
Some fungi, including that used as baker's yeasthave mating types that create a duality Six Nine Sex to male and female roles. Many species of higher fungi [ clarification needed ] produce mushrooms as part of their sexual reproduction. Within the mushroom diploid cells are formed, later dividing into haploid spores.
Sexual reproduction is common among parasitic protozoa but rare among free-living protozoawhich usually reproduce asexually Seriesbang Tu food is scarce or the environment changes drastically.
Both anisogamy and isogamy are found in free-living protozoa. A sexual system is a distribution of male and female functions across organisms in a species. Gonochoric individuals are either male or female throughout their lives.
Sexual conflict underlies the evolutionary distinction between male and female with the distinction starting from anisogamy. Anisogamy evolved due to disruptive selection leading to small gametes and large gametes.
The biological cause of an organism developing into one sex or the other is called sex determination. The cause may be genetic, environmental, haplodiploidyor multiple factors.
In plants that are sexually dimorphic, such as the liverwort Marchantia polymorpha or the dioecious species in the flowering plant genus Silenesex may also be determined by sex chromosomes. It is the male gamete that determines the sex of the offspring. XY sex determination is found in other organisms, including insects like the common fruit fly and some plants.
In birds, which have a ZW sex-determination systemthe W chromosome carries factors responsible for female development, and default development is male. It is the female gamete that determines the sex of the offspring.
This system is used by birds, some fish, and some crustaceans. The majority of butterflies and moths also have a ZW sex-determination system. All other chromosomes in these diploid organisms are paired, but organisms may inherit one or two X chromosomes. In Solo Sex cricketsfor example, insects with a single X chromosome develop as male, while those with two develop as female.
In the Z0 sex-determination systemmales have two Z chromosomes whereas females have one. This system is found in several species of moths.
For many species, sex is not determined by Six Nine Sex traits, but instead by environmental factors such as temperature experienced during development or later in life. The bonelliidae larvae can Six Nine Sex develop as males when they encounter a female. In the fern Ceratopteris and other homosporous fern species, the default sex is hermaphrodite, but individuals which grow in soil that has previously supported hermaphrodites are influenced by the pheromone antheridiogen to develop as male.
Some species can change sex over the course of their lifespan, a phenomenon called sequential hermaphroditism. In clownfishsmaller fish are male, and the dominant and largest fish in a group becomes female; when a dominant female is absent, then her partner changes sex.
In many wrasses Six Nine Sex opposite is true—the fish are initially female and become male when they reach a certain size. In these species, the temperature experienced by the embryos during their development determines their sex. Other insects, including honey bees and antsuse a haplodiploid sex-determination system.
The English statistician and biologist Ronald Fisher outlined why this is so in what has come to be known as Fisher's principle. Anisogamy is the fundamental difference between male and female.
In other species, there may be differences in coloration or other features, and may be so pronounced that the different sexes may be mistaken for two entirely different taxa. The sexes across gonochoric species usually differ in behavior. Primary sex characteristics are organs directly involved in reproduction such as the testes or ovarieswhile secondary sex characteristics in humans for example are body hairbreastsand distribution of fat.
Organisms that have intermediate sex characteristics between male and female are called intersexthis can be caused by extra sex chromosomes or by hormonal abnormality during fetal development. In many animals and some plants, individuals of male and female sex differ in size and appearance, a phenomenon called sexual dimorphism. Mammal species with extreme sexual size dimorphism tend to have highly polygynous mating systems—presumably due to selection for success in competition with other males—such as the elephant seals.
Other examples demonstrate that it is the preference of females that drives sexual dimorphism, such as in the case of the stalk-eyed fly. Females are the Telugu Hot Porn sex in a majority of animals. Sexual dimorphism can be extreme, with males, such as Backroom Casting Rebecca anglerfishliving parasitically on the female.
Some plant species also exhibit dimorphism in which the females are significantly larger than the males, such as in the moss genus Dicranum  and the liverwort genus Sphaerocarpos.
One proposed explanation for this is the handicap principle.
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Sex is a trait that determines an individual's reproductive function, male or female , in animals and plants that propagate their species through sexual reproduction. Commonly in plants and animals, male organisms produce smaller gametes spermatozoa, sperm while female organisms produce larger gametes ova , often called egg cells. Males and females of a species may be similar sexual monomorphism , or have physical differences sexual dimorphism. The differences 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. The terms "male" and "female" typically do not apply in sexually undifferentiated species in which the individuals are isomorphic and the gametes are isogamous indistinguishable in size and morphology , such as the green alga Ulva lactuca.