- Male Gametophyte Vs Female Gametophyte
- Example Of Gametophyte Moss
- Sporophyte And Gametophyte Examples
- What Is Gametophyte
- Example Of A Plant Gametophyte
Gymnosperms are flowerless plants that produce cones and seeds. The term gymnosperm literally means 'naked seed,' as gymnosperm seeds are not encased within an ovary. Rather, they sit exposed on the surface of leaf-like structures called bracts. Gymnosperms are vascular plants of the subkingdom Embyophyta and include conifers, cycads, ginkgoes, and gnetophytes. Some of the most recognizable examples of these woody shrubs and trees include pines, spruces, firs, and ginkgoes. Gymnosperms are abundant in temperate forest and boreal forest biomes with species that can tolerate moist or dry conditions.
- Gametophytes are tipped with either inverted cone-shaped areas (archegonia) or male reproductive organs (antheridia). Released sperm (antherizoids) need water since they swim to the archegonium. Sprouting from the gametophyte tip after fertilization, a sporophyte holds itself in place by anchoring a foot in the archegonium.
- Types of sex organs present in the gametophytes are: Archegonium: A multicellular sex organ in the female that creates eggs. Antheridium: A Multicellular sex organ in the male that produces sperm. Archegonium is like an ovary in females because both structures form haploid cells of the egg.
- A haploid gametophyte cell contains a fixed number of unpaired chromosomes. It gives rise to diploid sporophyte, which however contains twice the number of paired chromosomes. Diploid zygotes formed by the fusion of haploid sperm and eggs produced by gametophytes. Diploid zygotes grows into a sporophyte.
Unlike angiosperms, gymnosperms do not produce flowers or fruit. They are believed to be the first vascular plants to inhabit land appearing in the Triassic Period around 245-208 million years ago. The development of a vascular system capable of transporting water throughout the plant enabled gymnosperm land colonization. Today, there over one thousand species of gymnosperms belonging to four main divisions: Coniferophyta, Cycadophyta, Ginkgophyta, and Gnetophyta.
Male Gametophyte Vs Female Gametophyte
Alternation of Generations. A sporophyte is a plant that produces spores (asexual reproduction) and a gametophyte is a plant that produces gametes (sexual reproduction). The word gametes refers to sperm and eggs. You need two gametes to make a new plant; otherwise you might end up with a sperm plant or an egg plant. Examples of angiosperms include oak trees, maples, birches, forsythias, daisies, lilies and lilac bushes. Gymnosperm means 'naked seed,' although the seeds of these types of plants aren't found in fruit as they are in angiosperms.
Coniferophyta
The Coniferophyta division contains conifers, which have the greatest variety of species among gymnosperms. Most conifers are evergreen (retain their leaves throughout the year) and include some of the largest, tallest and oldest trees on the planet. Examples of conifers include pines, sequoias, firs, hemlock, and spruces. Conifers are an important economic source of lumber and products, such as paper, that are developed from wood. Gymnosperm wood is considered softwood, unlike the hardwood of some angiosperms.
The word conifer means 'cone-bearer,' a distinct characteristic common to conifers. Cones house the male and female reproductive structures of conifers. Most conifers are monoecious, meaning that both male and female cones can be found on the same tree.
Another readily identifiable trait of conifers is their needle-like leaves. Different conifer families, such as Pinaceae (pines) and Cupressaceae (cypresses), are distinguished by the type of leaves present. Pines have single needle-like leaves or needle-leaf clutters along the stem. Cypresses have flat, scale-like leaves along the stems. Other conifers of the genus Agathis have thick, elliptical leaves, and conifers of the genus Nageia have broad, flat leaves.
Conifers are conspicuous members of the taiga forest biome and have adaptations for life in the cold environment of boreal forests. The tall, triangular shape of the trees allows snow to fall from the branches more readily and prevents them from breaking under the weight of the ice. The needle-leaf conifers also have a waxy coat on the leaf surface to help prevent water loss in the dry climate.
Cycadophyta
The Cycadophyta division of gymnosperms include cycads. Cycads are found in tropical forests and subtropical regions. These evergreen plants have a feather-like leaf structure and long stems that spread the large leaves out over the thick, woody trunk. At first glance, cycads may resemble palm trees, but they are not related. These plants can live for many years and have a slow growth process. The King Sago palm, for example, may take up to 50 years to reach 10 feet.
Unlike many conifers, cycad trees either produce only male cones (produce pollen) or female cones (produce ovules). Female cone-producing cycads will only produce seeds if a male is within the vicinity. Cycads rely mainly on insects for pollination, and animals aid in dispersal of their large, colorful seeds.
The roots of cycads are colonized by the photosynthetic bacteriacyanobacteria. These microbes produce certain poisons and neurotoxins that accumulate in the plant seeds. The toxins are thought to provide protection against bacteria and fungal parasites. Cycad seeds can be dangerous to pets and humans if ingested.
Ginkgophyta
Ginkgo biloba are the only surviving plants of the Ginkgophyta division of gymnosperms. Today, naturally-growing ginkgo plants are exclusive to China. Ginkgoes can live for thousands of years and are characterized by fan-shaped, deciduous leaves that turn yellow in autumn. Ginkgo biloba are quite large, with the tallest trees reaching 160 feet. Older trees have thick trunks and deep roots.
Ginkgoes thrive in well sunlit areas that receive lots of water and have plenty of soil drainage. Like cycads, ginkgo plants produce either male or female cones and have sperm cells that use flagella to swim toward the egg in the female ovule. These durable trees are fire-resistant, pest-resistant, and disease-resistant, and they produce chemicals thought to have medicinal value, including several flavinoids and terpenes with antioxidant, anti-inflammatory, and antimicrobial properties.
Gnetophyta
The gymnosperm division Gnetophyta has a small number of species (65) found within three genera: Ephedra, Gnetum, and Welwitschia. Many of the species from the genus Ephedra are shrubs that can be found in desert regions of the Americas or in the high, cool regions of the Himalayan mountains in India. Certain Ephedra species have medicinal properties and are the source of the decongestant drug ephedrine. Ephedra species have slender stems and scale-like leaves.
Gnetum species contain some shrubs and trees, but most are woody vines that climb around other plants. They inhabit tropical rain forests and have broad, flat leaves that resemble the leaves of flowering plants. The male and female reproductive cones are contained on separate trees and often resemble flowers, though they are not. The vascular tissue structure of these plants is also similar to that of flowering plants.
Welwitschia has a single species, W. mirabilis. These plants live only in the African desert of Namibia. They are very unusual in that they have a large stem that remains close to the ground, two large arching leaves that split into other leaves as they grow, and a large, deep taproot. This plant can withstand the extreme heat of the desert with highs of 50°C (122°F), as well as the lack of water (1-10 cm yearly). Male W. mirabilis cones are brightly colored, and both male and female cones contain nectar to attract insects.
Gymnosperm Life Cycle
In the gymnosperm life cycle, plants alternate between a sexual phase and an asexual phase. This type of life cycle is known as alternation of generations. Gamete production occurs in the sexual phase or gametophyte generation of the cycle. Spores are produced in the asexual phase or sporophyte generation. Unlike in non-vascular plants, the dominant phase of the plant life cycle for vascular plants is the sporophtye generation.
In gymnosperms, the plant sporophyte is recognized as the bulk of the plant itself, including roots, leaves, stems, and cones. The cells of the plant sporophyte are diploid and contain two complete sets of chromosomes. The sporophyte is responsible for the production of haploid spores through the process of meiosis. Containing one complete set of chromosomes, spores develop into haploid gametophytes. The plant gametophytes produce male and female gametes which unite at pollination to form a new diploid zygote. The zygote matures into a new diploid sporophyte, thus completing the cycle. Gymnosperms spend most of their life cycle in the sporophyte phase, and the gametophyte generation is totally dependent upon the sporophyte generation for survival.
Gymnosperm Reproduction
Female gametes (megaspores) are produced in gametophyte structures called archegonia located in ovulate cones. Male gametes (microspores) are produced in pollen cones and develop into pollen grains. Some gymnosperm species have male and female cones on the same tree, while others have separate male or female cone producing trees. In order for pollination to take place, gametes must come into contact with one another. This typically occurs via wind, animal, or insect transfer.
Fertilization in gymnosperms occurs when pollen grains contact the female ovule and germinate. Sperm cells make their way to the egg inside the ovule and fertilize the egg. In conifer and gnetophytes, sperm cells have no flagella and must reach the egg via the formation of a pollen tube. In cycads and ginkgoes, the flagellated sperm swim toward the egg for fertilization. Upon fertilization, the resulting zygote develops within the gymnosperm seed and forms a new sporophyte.
Key Points
- Gymnosperms are flowerless, seed-producing plants. They belong to the subkingdom Embophyta.
- The term 'gymnosperm' literally means 'naked seed.' This is because the seeds produced by gymnosperms are not encased in an ovary. Instead, gymnosperm seeds sit exposed on the surface of leaf-like structures called bracts.
- The four main divisions of gymnosperms are Coniferophyta, Cycadophyta, Ginkgophyta, and Gnetophyta.
- Gymnosperms are often found in temperate forest and boreal forest biomes. Common types of gymnosperms are conifers, cycads, ginkgoes, and gnetophytes.
Sources
Asaravala, Manish, et al. “Triassic Period: Tectonics and Paleoclimate.” Tectonics of the Triassic Period, University of Califonia Museum of Paleontology, www.ucmp.berkeley.edu/mesozoic/triassic/triassictect.html.
Frazer, Jennifer. “Are Cycads Social Plants?” Scientific American Blog Network, 16 Oct. 2013, blogs.scientificamerican.com/artful-amoeba/are-cycads-social-plants/.
Pallardy, Stephen G. “The Woody Plant Body.” Physiology of Woody Plants, 20 May 2008, pp. 9–38., doi:10.1016/b978-012088765-1.50003-8.
Wagner, Armin, et al. “Lignification and Lignin Manipulations in Conifers.” Advances in Botanical Research, vol. 61, 8 June 2012, pp. 37–76., doi:10.1016/b978-0-12-416023-1.00002-1.
gametophyte: The gamete-bearing individual or phase in the lifecycle of a plant having alternation of generations
sporophyte: The spore-producing individual or phase in the lifecycle of a plant having alternation of generations
Gametophyte and sporophyte?
Why does the sporophyte of mosses remain attached to the gametophyte?
Because the sporophyte grows out of the gametophyte.
Which stage is the main stage of moss sporophyte or gametophyte?
Gametophyte is the main stage in moss and sporophyte is dependent on gametophyte.
How have the sporophyte and gametophyte changed as plants have evolved?
The gametophyte has become smaller, and the sporophyte has become larger. To begin with main plant body was gametophytic and sporophyte was dependent on it. Later on, as the evolution progressed, both gametophyte and sporophyte became independent and ultimatly gametophyte became dependent on sporophyte.
For which does the sporophyte generation grow out of the gametophyte and remain parasitic upon the gametophyte?
In moss, where the sporophyte grows directly out of the top of the gametophyte.
Compare the gametophyte and sporophyte of a fern?
Example Of Gametophyte Moss
the gametophyte is only a haploid while the sporophyte is only a dploid
Does gametophyte generation depends on sporophyte generation in ferns?
it does not depending on the sporophyte generation, in fact the sporophyte itself that depending on the gametophyte generation -kayo93-
In mosses why is the sporophyte stage dependent on the gametophyte stage?
in mosses why is the sporophyte stage dependent on the gametophyte stage
Is the gametophyte or sporophyte dominant in mosses?
Sporophyte And Gametophyte Examples
How does the sporophyte generation of a plant differ from the gametophyte generation?
The sporophyte generation carries its chromosomes as doubles. .. The spores then develop into the gametophyte generation. In most plants, the gametophyte is tiny compared to the sporophyte. As its name implies, the gametophyte generationproduces sex cells - sperm and eggs. Iclone 7 free download with crack.
What is more dominant the gametophyte or sporophyte?
Angiosperms' and Gymnosperms' SPOROPHYTE generation is more dominant than it's GAMETOPHYTE generation.
What is female gametophyte?
Embryo sac is the female gametophyte of flowering plants. Situated in the flower. It is dependent on the sporophyte (what we call plant) for nutrition. here the gametophyte is reduced and sporophyte is dominant. In lower plants the female gametophyte is prominent and independent where it can photosynthesize. Usually it is called as a thallus. Here the sporophyte is reduced and the gametophyte is dominant.
How are the fern sporophyte and gametophyte stage the same?
In reference to the sporophyte and gametophyte, are the stages of the plant's life cycle thus being the same.
What is the dominant stage of the fern life cycle what is the relationship of the fern gametophyte and sporophyte?
in the life cycle of a fern, the dominant and recognizable stage is the diploid sporophyte. the the younger sporophyte grows from the gametophyte.
How does the gametophyte generation of a plant differ from the sporophyte generation?
In most plants, the sporophyte generation is dominant. In fern, for example, the fern itself is the sporophyte. This organism produces spores that fall to the substrate below and grow into a separate organism called a gametophyte. The gametophyte produces sperm and eggs in order to produce a new sporophyte which grows out of the gametophyte's body, destroying it. It is important to note that the gametophyte is haploid and the sporophyte is dploid.
What is the difference between sporophyte and gametophyte?
Sporophytes reproduce with spores, while gametophytes reproduce sexually Of the two, it is the gametophyte is larger than the sporophyte.
In which group of plants are both the sporophyte and gametophyte free- living?
Both the sporophyte and gametophyte are free-living and homomorphic, and belong to Cladophora.
What is true of all seed plants The gametophyte is dominant Seeds are enclosed in a vessel The gametophyte is free living The sporophyte is dominant?
During the life cycle of a plant gametophyte is to n as sporophyte is to?
Basically, plants have two stages in their life cycle, they can appear as a gametophyte or a sporophyte.
Do eggs have gametophyte or sporophyte?
Will megaspores divide to form the female gametophyte or the sporophyte?
What is the definition of the gametophyte and sporophyte generation of gymnosperms?
Gametophyte is the sexual form of a plant in alternation of generations. Sporophyte is the form of a plant that produces spores in alternation of generations.
What are the differences between the gametophyte stage and the sporophyte stage of the plant life-cycle?
the gametophyte stage begins with meiosis and the sporophyte stage begins with fertilization.
What Is Gametophyte
What is a Chromosome complement?
Example Of A Plant Gametophyte
The chromosome compliment of a gametophyte is a sporophyte.
Compare and contrast the gametophyte plant of the moss with the gametophyte plant of the fern?
The gametophyte of moss is the dominant structure. The sporophyte of ferns is the dominant structure.