| 单词 | gametophyte |
| 例句 | The female gametophyte produces eggs, and the male gametophyte produces sperm. Fundamentals of Biology 2015-01-01T00:00:00Z The gametophyte gives rise to the gametes, or reproductive cells, by mitosis. Concepts of Biology 2013-04-25T00:00:00Z Although all plants utilize some version of the alternation of generations, the relative size of the sporophyte and the gametophyte and the relationship between them vary greatly. Biology for AP Courses 2022-06-09T00:00:00Z The male gametophyte with its two cells is then surrounded by a thick wall that protects it. Miller & Levine Biology 2018-01-01T00:00:00Z This gametophyte plant looks completely different from the sporophyte phase: it is a small, flat, amorphous blob. Spore heroes: unlocking the life-cycle secrets of the earliest land plants 2018-05-24T04:00:00Z The gametophyte produces gametes, two of which fuse to form a diploid zygote. Fundamentals of Biology 2015-01-01T00:00:00Z After germinating from a spore, the gametophyte produces both male and female gametangia, usually on the same individual. Concepts of Biology 2013-04-25T00:00:00Z In plants such as moss, the gametophyte organism is the free-living plant, and the sporophyte is physically dependent on the gametophyte. Biology for AP Courses 2022-06-09T00:00:00Z These seven cells are the female gametophyte, known as the embryo sac. Miller & Levine Biology 2018-01-01T00:00:00Z In ferns, the sporophyte phase is dominant, but the gametophyte is still hanging in there as an independent plant. Spore heroes: unlocking the life-cycle secrets of the earliest land plants 2018-05-24T04:00:00Z Most plants exhibit alternation of generations, which is described as haplodiplodontic: the haploid multicellular form, known as a gametophyte, is followed in the development sequence by a multicellular diploid organism: the sporophyte. Fundamentals of Biology 2015-01-01T00:00:00Z The male spores are called microspores because of their smaller size; the comparatively larger megaspores will develop into the female gametophyte. Concepts of Biology 2013-04-25T00:00:00Z In other plants, such as ferns, both the gametophyte and sporophyte plants are free-living; however, the sporophyte is much larger. Biology for AP Courses 2022-06-09T00:00:00Z Each gametophyte produces reproductive cells called gametes, also known as sperm and egg cells. Miller & Levine Biology 2018-01-01T00:00:00Z In liverworts like Marchantia, which lives in most soggy places worldwide, the gametophyte is the dominant phase – the thing you would think of as the plant. Spore heroes: unlocking the life-cycle secrets of the earliest land plants 2018-05-24T04:00:00Z Bryophytes may have been successful at the transition from an aquatic habitat to land, but they are still dependent on water for reproduction, and absorb moisture and nutrients through the gametophyte surface. Fundamentals of Biology 2015-01-01T00:00:00Z When the haploid spore germinates, it generates a multicellular gametophyte by mitosis. Concepts of Biology 2013-04-25T00:00:00Z In seed plants, such as magnolia trees and daisies, the gametophyte is composed of only a few cells and, in the case of the female gametophyte, is completely retained within the sporophyte. Biology for AP Courses 2022-06-09T00:00:00Z An important trend in plant evolution is the reduction in size of the gametophyte and the increase in size of the sporophyte. Miller & Levine Biology 2018-01-01T00:00:00Z The sporophyte phase is completely dependent on its gametophyte for photosynthesis, and does not live as a separate plant. Spore heroes: unlocking the life-cycle secrets of the earliest land plants 2018-05-24T04:00:00Z The gametophyte is now an inconspicuous, but still independent, organism. Fundamentals of Biology 2015-01-01T00:00:00Z In both seedless and seed plants, the female gametophyte provides nutrition, and in seed plants, the embryo is also protected as it develops into the new generation of sporophyte. Concepts of Biology 2013-04-25T00:00:00Z The lower half of the green thing in this picture is the tiny, gauzy fern gametophyte — the fern you don’t see: Ferns Stole Rare Gene From Unlikely Source 2014-05-06T13:45:46Z The gametophyte is the dominant stage of the life cycle and carries out most of the photosynthesis. Miller & Levine Biology 2018-01-01T00:00:00Z Does this mean that the sporophyte phase of the earliest land plants was equally dependent on its gametophyte? Spore heroes: unlocking the life-cycle secrets of the earliest land plants 2018-05-24T04:00:00Z Male gametes reach female gametophyte and the egg cell gamete though a pollen tube: an extension of a cell within the pollen grain. Fundamentals of Biology 2015-01-01T00:00:00Z Most plants exhibit alternation of generations, which is described as haplodiplontic: the haploid multicellular form known as a gametophyte is followed in the development sequence by a multicellular diploid organism, the sporophyte. Concepts of Biology 2013-04-25T00:00:00Z But — and this can’t be underlined enough — this thing that looked like a gametophyte but sprouted from a mutant sporophyte was diploid. Mosses Make Two Different Plants From the Same Genome, and a Single Gene Can Make the Difference 2013-05-12T19:45:00.233Z The entire male gametophyte of a seed plant is found in a pollen grain. Miller & Levine Biology 2018-01-01T00:00:00Z Where is the gametophyte in pine trees and daffodils? Ferns, Secret Ninja Ferns, and their Alluring Asexual Bits 2012-05-07T11:15:00.827Z Plants have two distinct stages in their lifecycle: the gametophyte stage and the sporophyte stage. Fundamentals of Biology 2015-01-01T00:00:00Z The male gametophyte releases sperm, which must swim—propelled by their flagella—to reach and fertilize the female gamete or egg. Concepts of Biology 2013-04-25T00:00:00Z Since the haploid moss — the gametophyte — likely evolved first, it still resembles green plants’ filamentous green algal ancestors. Mosses Make Two Different Plants From the Same Genome, and a Single Gene Can Make the Difference 2013-05-12T19:45:00.233Z When mature, each gametophyte contains a few large egg cells, which can be fertilized by sperm. Miller & Levine Biology 2018-01-01T00:00:00Z In flowering plants, the gametophyte usually doesn’t exceed a handful of cells. Ferns, Secret Ninja Ferns, and their Alluring Asexual Bits 2012-05-07T11:15:00.827Z The haploid gametophyte produces the male and female gametes by mitosis in distinct multicellular structures. Fundamentals of Biology 2015-01-01T00:00:00Z Only a single surviving haploid cell will develop into a female multicellular gametophyte that encloses an egg. Concepts of Biology 2013-04-25T00:00:00Z The thing you think of as moss is actually the gametophyte — the haploid organism. Mosses Make Two Different Plants From the Same Genome, and a Single Gene Can Make the Difference 2013-05-12T19:45:00.233Z Once the pollen tube reaches the female gametophyte, one sperm nucleus disintegrates; the other fertilizes the egg contained within the female gametophyte. Miller & Levine Biology 2018-01-01T00:00:00Z In a later paper Pearson considerably extended our knowledge of the reproduction and gametophyte of this genus. Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 7 "Gyantse" to "Hallel" 2011-12-26T03:00:11.613Z After reaching maturity, the diploid sporophyte produces spores by meiosis, which in turn divide by mitosis to produce the haploid gametophyte. Fundamentals of Biology 2015-01-01T00:00:00Z The seed that is formed contains three generations of tissues: the seed coat that originates from the parent plant tissue, the female gametophyte that will provide nutrients, and the embryo itself. Concepts of Biology 2013-04-25T00:00:00Z There is thus in all the Basidiales an alternation of generations, obscured, however, by the apogamous transition from the gametophyte to sporophyte. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 3 "Frost" to "Fyzabad" 2011-08-15T02:00:28.473Z It consists of a capsule usually borne on a longer or shorter stalk or seta, the base of which is inserted into the tissues of the gametophyte. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria" The last-mentioned case has been regarded as representing an apogamous development of the sporophyte from the gametophyte comparable to the cases of apogamy described in Ferns. Encyclopaedia Britannica, 11th Edition, Volume 2, Part 1, Slice 1 The new gametophyte produces gametes, and the cycle continues. Fundamentals of Biology 2015-01-01T00:00:00Z One of these is larger than the others and undergoes mitosis to form the female gametophyte or embryo sac. Concepts of Biology 2013-04-25T00:00:00Z The matter is complicated by the apogamous transition from gametophyte to sporophyte in the absence of the ascogonium; also by the fact that there are normally two fusions in the life-history as mentioned earlier. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 3 "Frost" to "Fyzabad" 2011-08-15T02:00:28.473Z The gametophyte is developed from the spore and bears the sexual organs; the sporogonium is developed from the fertilized egg and produces spores. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria" The gametophyte phase is dominant in these plants. Fundamentals of Biology 2015-01-01T00:00:00Z In ferns, the gametophyte is free-living and very distinct in structure from the diploid sporophyte. Fundamentals of Biology 2015-01-01T00:00:00Z In a bryophyte, all the conspicuous vegetative organs belong to the haploid organism, or gametophyte. Concepts of Biology 2013-04-25T00:00:00Z The ordinary mycelium is the gametophyte since it bears the ascogonia and antheridia when present; the ascogenous hyphae with their asci represent the sporophyte since they are derived from the fertilized ascogonium. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 3 "Frost" to "Fyzabad" 2011-08-15T02:00:28.473Z Thus in Pellia the nuclei of the gametophyte have eight chromosomes and those of the sporophyte sixteen. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria" After germinating from a spore, the resulting gametophyte produces both male and female gametangia, usually on the same individual. Fundamentals of Biology 2015-01-01T00:00:00Z When the pollen lands on a female scale, a pollen tube grows toward the female gametophyte, which consists of an ovule containing the megaspore. Fundamentals of Biology 2015-01-01T00:00:00Z The organism in the photograph is in the gametophyte stage. Concepts of Biology 2013-04-25T00:00:00Z When the haploid spore germinates in a hospitable environment, it generates a multicellular gametophyte by mitosis. Fundamentals of Biology 2015-01-01T00:00:00Z The gametophyte is always the independently living individual upon which the spore-bearing generation is throughout its life dependent. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria" The completion of the bryophyte and pterophyte life cycle requires water because the male gametophyte releases sperm, which must swim—propelled by their flagella—to reach and fertilize the female gamete or egg. Fundamentals of Biology 2015-01-01T00:00:00Z One of the megaspores divides to form the multicellular female gametophyte, while the others divide to form the rest of the structure. Fundamentals of Biology 2015-01-01T00:00:00Z The dominant phase of the life cycle of hornworts is the short, blue-green gametophyte. Concepts of Biology 2013-04-25T00:00:00Z What makes them the first true seed plants is that they developed structures called cupules to enclose and protect the ovule—the female gametophyte and associated tissues—which develops into a seed upon fertilization. Fundamentals of Biology 2015-01-01T00:00:00Z The Anthocerotales are a small and very distinct group, in which the gametophyte is a thallus, while the sporogonium possesses a sterile columella and is capable of long-continued growth and spore production. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria" The life cycle of a gymnosperm involves alternation of generations, with a dominant sporophyte in which the female gametophyte resides, and reduced gametophytes. Fundamentals of Biology 2015-01-01T00:00:00Z It takes approximately one year for the pollen tube to grow and migrate towards the female gametophyte. Fundamentals of Biology 2015-01-01T00:00:00Z At the same time, the trend led to a reduction in the size of the gametophyte, from a conspicuous structure to a microscopic cluster of cells enclosed in the tissues of the sporophyte. Concepts of Biology 2013-04-25T00:00:00Z Only the large megaspore survives; it produces the female gametophyte, referred to as the embryo sac. Fundamentals of Biology 2015-01-01T00:00:00Z The organization of the gametophyte stands in the closest relation to the factors of light and moisture in the environment. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria" A megaspore develops into a female gametophyte containing a haploid egg. Fundamentals of Biology 2015-01-01T00:00:00Z They originate from the base of the gametophyte, but are not the major route for the absorption of water and minerals. Fundamentals of Biology 2015-01-01T00:00:00Z The dominant stage of the life cycle is the gametophyte. Concepts of Biology 2013-04-25T00:00:00Z Both the gametophyte and sporophyte stages are multicellular. Fundamentals of Biology 2015-01-01T00:00:00Z When artificially divided small fragments of the gametophyte are found to be capable of growing into new individuals. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria" In both seedless and seed plants, the female gametophyte provides protection and nutrients to the embryo as it develops into the new generation of sporophyte. Fundamentals of Biology 2015-01-01T00:00:00Z The zygote, protected by the archegonium, divides and grows into a sporophyte, still attached by its foot to the gametophyte. Fundamentals of Biology 2015-01-01T00:00:00Z The gametophyte is longest phase of the life cycle. Concepts of Biology 2013-04-25T00:00:00Z The male spores are called microspores, because of their smaller size, and develop into the male gametophyte; the comparatively larger megaspores develop into the female gametophyte. Fundamentals of Biology 2015-01-01T00:00:00Z Parallel with the evolution of the gametophyte in form and structure, a progression can be traced in the sporogonium, although the simplest sporogonia available for study may owe much of their simplicity to reduction. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria" In a bryophyte, all the conspicuous vegetative organs—including the photosynthetic leaf-like structures, the thallus, stem, and the rhizoid that anchors the plant to its substrate—belong to the haploid organism or gametophyte. Fundamentals of Biology 2015-01-01T00:00:00Z The calyptra buds to form a mature gametophyte. Fundamentals of Biology 2015-01-01T00:00:00Z The zygote grows into a small sporophyte still attached to the parent gametophyte. Fundamentals of Biology 2015-01-01T00:00:00Z The short, blue-green gametophyte is the dominant phase of the lifecycle of a hornwort. Fundamentals of Biology 2015-01-01T00:00:00Z The spores germinate and grow into a green gametophyte 1n that resembles lettuce. Fundamentals of Biology 2015-01-01T00:00:00Z The gametophyte contains antheridia that produce, sperm and archegonia that produce eggs. Fundamentals of Biology 2015-01-01T00:00:00Z The sporophyte is diploid and the gametophyte is haploid. Fundamentals of Biology 2015-01-01T00:00:00Z The seed that is formed contains three generations of tissues: the seed coat that originates from the sporophyte tissue, the gametophyte that will provide nutrients, and the embryo itself. Fundamentals of Biology 2015-01-01T00:00:00Z When the pollen lands on a female scale, a pollen tube grows toward the female gametophyte, which consists of an ovule containing the megaspore. Fundamentals of Biology 2015-01-01T00:00:00Z The micropyle allows the pollen tube to enter the female gametophyte for fertilization. Fundamentals of Biology 2015-01-01T00:00:00Z The male and female gametophyte structures are present on separate male and female cones in gymnosperms, whereas in angiosperms, they are a part of the flower. Fundamentals of Biology 2015-01-01T00:00:00Z Sporangia form on the underside of the gametophyte. Fundamentals of Biology 2015-01-01T00:00:00Z The haploid spores germinate and give rise to the next generation of gametophyte. Fundamentals of Biology 2015-01-01T00:00:00Z In angiosperms, the female gametophyte exists in an enclosed structure—the ovule—which is within the ovary; in gymnosperms, the female gametophyte is present on exposed bracts of the female cone. Fundamentals of Biology 2015-01-01T00:00:00Z The female gametophyte is formed from mitotic divisions of the megaspore, forming an eight-nuclei ovule sac. Fundamentals of Biology 2015-01-01T00:00:00Z The life cycle of higher plants is dominated by the sporophyte stage, with the gametophyte borne on the sporophyte. Fundamentals of Biology 2015-01-01T00:00:00Z The newly formed zygote grows into a sporophyte that emerges from the gametophyte and grows by mitosis into the next generation sporophyte. Fundamentals of Biology 2015-01-01T00:00:00Z In bryophytes, such as mosses, the haploid gametophyte is more developed than the sporophyte. Fundamentals of Biology 2015-01-01T00:00:00Z The female gametophyte is contained within a structure called the archegonium. Fundamentals of Biology 2015-01-01T00:00:00Z The male gametophyte containing the generative cell splits into two sperm nuclei, one of which fuses with the egg, while the other degenerates. Fundamentals of Biology 2015-01-01T00:00:00Z While the details may vary between species, the overall development of the female gametophyte has two distinct phases. Fundamentals of Biology 2015-01-01T00:00:00Z The photo shows a young sporophyte with a fan-shaped leaf growing from a lettuce-like gametophyte. Fundamentals of Biology 2015-01-01T00:00:00Z |
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