The penis contains a tube through which semen a fluid containing sperm travels. In female mammals the vagina connects with the uterus , an organ which directly supports the development of a fertilized embryo within a process called gestation. Because of their motility, animal sexual behavior can involve coercive sex. Traumatic insemination , for example, is used by some insect species to inseminate females through a wound in the abdominal cavity—a process detrimental to the female's health.

Like animals, plants have developed specialized male and female gametes. The female gametes of seed plants are contained within ovules ; once fertilized by pollen these form seeds which, like eggs, contain the nutrients necessary for the development of the embryonic plant. Many plants have flowers and these are the sexual organs of those plants. Flowers are usually hermaphroditic, producing both male and female gametes.

The female parts, in the center of a flower, are the pistils , each unit consisting of a carpel , a style and a stigma. One or more of these reproductive units may be merged to form a single compound pistil.

Within the carpels are ovules which develop into seeds after fertilization. The male parts of the flower are the stamens: 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 an ovule that eventually develops into a seed. In pines and other conifers the sex organs are conifer cones and have male and female forms. The more familiar female cones are typically more durable, containing ovules within them.

Male cones are smaller and produce pollen which is transported by wind to land in female cones. As with flowers, seeds form within the female cone after pollination. Because plants are immobile, they depend upon passive methods for transporting pollen grains to other plants. Many plants, including conifers and grasses, produce lightweight pollen which is carried by wind to neighboring plants. Other plants have heavier, sticky pollen that is specialized for transportation by insects.

The plants attract these insects or larger animals such as humming birds and bats with nectar-containing flowers. These animals transport the pollen as they move to other flowers, which also contain female reproductive organs, resulting in pollination.

Most fungi reproduce sexually, having both a haploid and diploid stage in their life cycles. These fungi are typically isogamous , lacking male and female specialization: In some of these cases, the fusion is asymmetric, and the cell which donates only a nucleus and not accompanying cellular material could arguably be considered "male". Some fungi, including baker's yeast , have mating types that create a duality similar to male and female roles. Yeast with the same mating type will not fuse with each other to form diploid cells, only with yeast carrying the other mating type.

Many species of higher fungi produce mushrooms as part of their sexual reproduction. Within the mushroom diploid cells are formed, later dividing into haploid spores. The height of the mushroom aids the dispersal of these sexually produced offspring. The most basic sexual system is one in which all organisms are hermaphrodites , producing both male and female gametes— [ citation needed ] this is true of some animals e. The biological cause for an organism developing into one sex or the other is called sex determination.

In the majority of species with sex specialization, organisms are either male producing only male gametes or female producing only female gametes. Exceptions are common—for example, the roundworm C. Sometimes an organism's development is intermediate between male and female, a condition called intersex. Sometimes intersex individuals are called "hermaphrodite"; but, unlike biological hermaphrodites, intersex individuals are unusual cases and are not typically fertile in both male and female aspects.

In genetic sex-determination systems, an organism's sex is determined by the genome it inherits. Genetic sex-determination usually depends on asymmetrically inherited sex chromosomes which carry genetic features that influence development ; sex may be determined either by the presence of a sex chromosome or by how many the organism has.

Genetic sex-determination, because it is determined by chromosome assortment, usually results in a 1: Humans and other mammals have an XY sex-determination system: The "default sex," in the absence of a Y chromosome, is female-like. Thus, XX mammals are female and XY are male. In humans, biological sex is determined by five factors present at birth: XY sex determination is found in other organisms, including the common fruit fly and some plants.

In birds, which have a ZW sex-determination system , the opposite is true: The majority of butterflies and moths also have a ZW sex-determination system. In both XY and ZW sex determination systems, the sex chromosome carrying the critical factors is often significantly smaller, carrying little more than the genes necessary for triggering the development of a given sex.

Many insects use a sex determination system based on the number of sex chromosomes. This is called X0 sex-determination —the 0 indicates the absence of the sex chromosome. All other chromosomes in these organisms are diploid, but organisms may inherit one or two X chromosomes. In field crickets , for example, insects with a single X chromosome develop as male, while those with two develop as female.

Other insects, including honey bees and ants , use a haplodiploid sex-determination system. This sex-determination system results in highly biased sex ratios , as the sex of offspring is determined by fertilization rather than the assortment of chromosomes during meiosis. For many species, sex is not determined by inherited traits, but instead by environmental factors experienced during development or later in life.

Many reptiles have temperature-dependent sex determination: Many fish change sex over the course of their lifespan, a phenomenon called sequential hermaphroditism. In clownfish , smaller fish are male, and the dominant and largest fish in a group becomes female.

In many wrasses the opposite is true—most fish are initially female and become male when they reach a certain size. Sequential hermaphrodites may produce both types of gametes over the course of their lifetime, but at any given point they are either female or male. In some ferns the default sex is hermaphrodite, but ferns which grow in soil that has previously supported hermaphrodites are influenced by residual hormones to instead develop as male.

Many animals and some plants have differences between the male and female sexes in size and appearance, a phenomenon called sexual dimorphism. Sex differences in humans include, generally, a larger size and more body hair in men; women have breasts, wider hips, and a higher body fat percentage.

In other species, the differences may be more extreme, such as differences in coloration or bodyweight. Sexual dimorphisms in animals are often associated with sexual selection — the competition between individuals of one sex to mate with the opposite sex. In many cases the male of a species is larger than the female. 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 drive sexual dimorphism, such as in the case of the stalk-eyed fly.

Other animals, including most insects and many fish, have larger females. This may be associated with the cost of producing egg cells, which requires more nutrition than producing sperm—larger females are able to produce more eggs. Some plant species also exhibit dimorphism in which the females are significantly larger than the males, such as in the moss Dicranum [43] and the liverwort Sphaerocarpos.

In birds, males often have a more colourful appearance and may have features like the long tail of male peacocks that would seem to put the organism at a disadvantage e. One proposed explanation for this is the handicap principle. From Wikipedia, the free encyclopedia. This article is about sex in sexually reproducing organisms. For the act, see Sexual intercourse.

For other uses, see Sex disambiguation. Evolution of sexual reproduction. Different forms of anisogamy: A anisogamy of motile cells, B oogamy egg cell and sperm cell , C anisogamy of non-motile cells egg cell and spermatia. Different forms of isogamy: A isogamy of motile cells , B isogamy of non-motile cells, C conjugation. Sexual reproduction in animals. Female left and male right cones are the sex organs of pines and other conifers. Concise Oxford English Dictionary: Retrieved March 23, Either of the two main categories male and female into which humans and most other living things are divided on the basis of their reproductive functions.

The fact of belonging to one of these categories. The group of all members of either sex. The Science of Biology. A single body can function as both male and female. Sexual reproduction requires both male and female haploid gametes. In most species, these gametes are produced by individuals that are either male or female. Species that have male and female members are called dioecious from the Greek for 'two houses'. In some species, a single individual may possess both female and male reproductive systems.

Such species are called monoecious "one house" or hermaphroditic. Retrieved Feb 18, Biology of Plants 7 th ed. Freeman and Company Publishers. Conjugation 4 th ed. Biological Science 3rd ed.

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Choose the one you would like replaced: Diploid organisms can, in turn, form haploid cells gametes that randomly contain one of each of the chromosome pairs, via meiosis. Crossing over and fertilization the recombining of single sets of chromosomes to make a new diploid result in the new organism containing a different set of genetic traits from either parent.

In many organisms, the haploid stage has been reduced to just gametes specialized to recombine and form a new diploid organism; in others, such as cryptogamic plants the gametes are capable of undergoing cell division to produce multicellular haploid organisms. In either case, gametes may be externally similar, particularly in size isogamy , or may have evolved an asymmetry such that the gametes are different in size and other aspects anisogamy.

An individual that produces exclusively large gametes is female, and one that produces exclusively small gametes is male. Most sexually reproducing animals spend their lives as diploid, with the haploid stage reduced to single-cell gametes. These gametes combine to form embryos which develop into a new organism. The male gamete, a spermatozoon produced in vertebrates within the testes , is a small cell containing a single long flagellum which propels it.

They are specialized for motility, seeking out an egg cell and fusing with it in a process called fertilization.

Female gametes are egg cells produced in vertebrates within the ovaries , large immobile cells that contain the nutrients and cellular components necessary for a developing embryo.

In mammals, the fertilized embryo instead develops within the female, receiving nutrition directly from its mother. Animals are usually mobile and seek out a partner of the opposite sex for mating. Animals which live in the water can mate using external fertilization , where the eggs and sperm are released into and combine within the surrounding water. In most birds, both excretion and reproduction is done through a single posterior opening, called the cloaca —male and female birds touch cloaca to transfer sperm, a process called "cloacal kissing".

In humans and other mammals this male organ is the penis , which enters the female reproductive tract called the vagina to achieve insemination —a process called sexual intercourse. The penis contains a tube through which semen a fluid containing sperm travels.

In female mammals the vagina connects with the uterus , an organ which directly supports the development of a fertilized embryo within a process called gestation. Because of their motility, animal sexual behavior can involve coercive sex. Traumatic insemination , for example, is used by some insect species to inseminate females through a wound in the abdominal cavity—a process detrimental to the female's health.

Like animals, plants have developed specialized male and female gametes. The female gametes of seed plants are contained within ovules ; once fertilized by pollen these form seeds which, like eggs, contain the nutrients necessary for the development of the embryonic plant. Many plants have flowers and these are the sexual organs of those plants.

Flowers are usually hermaphroditic, producing both male and female gametes. The female parts, in the center of a flower, are the pistils , each unit consisting of a carpel , a style and a stigma. One or more of these reproductive units may be merged to form a single compound pistil.

Within the carpels are ovules which develop into seeds after fertilization. The male parts of the flower are the stamens: 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 an ovule that eventually develops into a seed. In pines and other conifers the sex organs are conifer cones and have male and female forms.

The more familiar female cones are typically more durable, containing ovules within them. Male cones are smaller and produce pollen which is transported by wind to land in female cones. As with flowers, seeds form within the female cone after pollination. Because plants are immobile, they depend upon passive methods for transporting pollen grains to other plants.

Many plants, including conifers and grasses, produce lightweight pollen which is carried by wind to neighboring plants. Other plants have heavier, sticky pollen that is specialized for transportation by insects. The plants attract these insects or larger animals such as humming birds and bats with nectar-containing flowers. These animals transport the pollen as they move to other flowers, which also contain female reproductive organs, resulting in pollination.

Most fungi reproduce sexually, having both a haploid and diploid stage in their life cycles. These fungi are typically isogamous , lacking male and female specialization: In some of these cases, the fusion is asymmetric, and the cell which donates only a nucleus and not accompanying cellular material could arguably be considered "male".

Some fungi, including baker's yeast , have mating types that create a duality similar to male and female roles. Yeast with the same mating type will not fuse with each other to form diploid cells, only with yeast carrying the other mating type. Many species of higher fungi produce mushrooms as part of their sexual reproduction.

Within the mushroom diploid cells are formed, later dividing into haploid spores. The height of the mushroom aids the dispersal of these sexually produced offspring.

The most basic sexual system is one in which all organisms are hermaphrodites , producing both male and female gametes— [ citation needed ] this is true of some animals e. The biological cause for an organism developing into one sex or the other is called sex determination. In the majority of species with sex specialization, organisms are either male producing only male gametes or female producing only female gametes. Exceptions are common—for example, the roundworm C.

Sometimes an organism's development is intermediate between male and female, a condition called intersex. Sometimes intersex individuals are called "hermaphrodite"; but, unlike biological hermaphrodites, intersex individuals are unusual cases and are not typically fertile in both male and female aspects. In genetic sex-determination systems, an organism's sex is determined by the genome it inherits.

Genetic sex-determination usually depends on asymmetrically inherited sex chromosomes which carry genetic features that influence development ; sex may be determined either by the presence of a sex chromosome or by how many the organism has. Genetic sex-determination, because it is determined by chromosome assortment, usually results in a 1: Humans and other mammals have an XY sex-determination system: The "default sex," in the absence of a Y chromosome, is female-like.

Thus, XX mammals are female and XY are male. In humans, biological sex is determined by five factors present at birth: XY sex determination is found in other organisms, including the common fruit fly and some plants. In birds, which have a ZW sex-determination system , the opposite is true: The majority of butterflies and moths also have a ZW sex-determination system. In both XY and ZW sex determination systems, the sex chromosome carrying the critical factors is often significantly smaller, carrying little more than the genes necessary for triggering the development of a given sex.

Many insects use a sex determination system based on the number of sex chromosomes. This is called X0 sex-determination —the 0 indicates the absence of the sex chromosome. All other chromosomes in these organisms are diploid, but organisms may inherit one or two X chromosomes.

In field crickets , for example, insects with a single X chromosome develop as male, while those with two develop as female. Other insects, including honey bees and ants , use a haplodiploid sex-determination system. This sex-determination system results in highly biased sex ratios , as the sex of offspring is determined by fertilization rather than the assortment of chromosomes during meiosis.

For many species, sex is not determined by inherited traits, but instead by environmental factors experienced during development or later in life. Many reptiles have temperature-dependent sex determination: Many fish change sex over the course of their lifespan, a phenomenon called sequential hermaphroditism.

In clownfish , smaller fish are male, and the dominant and largest fish in a group becomes female. In many wrasses the opposite is true—most fish are initially female and become male when they reach a certain size. Sequential hermaphrodites may produce both types of gametes over the course of their lifetime, but at any given point they are either female or male.

In some ferns the default sex is hermaphrodite, but ferns which grow in soil that has previously supported hermaphrodites are influenced by residual hormones to instead develop as male. Many animals and some plants have differences between the male and female sexes in size and appearance, a phenomenon called sexual dimorphism. Sex differences in humans include, generally, a larger size and more body hair in men; women have breasts, wider hips, and a higher body fat percentage.

In other species, the differences may be more extreme, such as differences in coloration or bodyweight. Sexual dimorphisms in animals are often associated with sexual selection — the competition between individuals of one sex to mate with the opposite sex. In many cases the male of a species is larger than the female. 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 drive sexual dimorphism, such as in the case of the stalk-eyed fly. Other animals, including most insects and many fish, have larger females. This may be associated with the cost of producing egg cells, which requires more nutrition than producing sperm—larger females are able to produce more eggs.

Some plant species also exhibit dimorphism in which the females are significantly larger than the males, such as in the moss Dicranum [43] and the liverwort Sphaerocarpos. In birds, males often have a more colourful appearance and may have features like the long tail of male peacocks that would seem to put the organism at a disadvantage e.

One proposed explanation for this is the handicap principle. From Wikipedia, the free encyclopedia. This article is about sex in sexually reproducing organisms. For the act, see Sexual intercourse. For other uses, see Sex disambiguation.

Evolution of sexual reproduction. Different forms of anisogamy: A anisogamy of motile cells, B oogamy egg cell and sperm cell , C anisogamy of non-motile cells egg cell and spermatia.

Different forms of isogamy: A isogamy of motile cells , B isogamy of non-motile cells, C conjugation. Sexual reproduction in animals. Female left and male right cones are the sex organs of pines and other conifers. Concise Oxford English Dictionary: Retrieved March 23, Either of the two main categories male and female into which humans and most other living things are divided on the basis of their reproductive functions.

סקס פרטי סיקס חינמ -

Street prostitute with tight pussy is worth every penny 6 min 1, hits. What Can You Earn? Different forms of anisogamy: Find more about Sex at Wikipedia's sister projects. Organisms of many species are specialized into male זקנות בסקס אמא זיון female varieties, each known as a sex. Sometimes intersex individuals are called "hermaphrodite"; but, unlike biological hermaphrodites, intersex individuals are unusual cases and are not typically fertile in both male and female aspects.

סקס פרטי סיקס חינמ -

Click here for Epoch Payment Support. Your active conversations limit has been reached 2 conversations in last 24 hours. Disregarding intermediates, the basic distinction between asexual and sexual reproduction is the way in which the genetic material is processed. German Giant Knockers in the Shower. Bacteria, for instance, reproduce asexually, but undergo a process by which a part of the genetic material of an individual donor is transferred to another recipient. The fact of belonging to one of these categories. Molecular Biology of the Cell 4th ed. Have something to say? Previous 1 2 3 4 Next. In mammals, the fertilized embryo instead develops within the female, receiving nutrition directly from its mother. One proposed explanation for this is the handicap principle.


סקס פרטי סיקס חינמ · 20.11.2016 at 18:57

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