Definition[ edit ] Alternation of generations is defined as the alternation of multicellular diploid and haploid forms in the organism's life cycle, regardless of whether or not these forms are free-living. The free-swimming, haploid gametes form a diploid zygote which germinates into a multicellular diploid sporophyte. The sporophyte produces free-swimming haploid spores by meiosis that germinate into haploid gametophytes. For example, in all bryophytes the gametophyte generation is dominant and the sporophyte is dependent on it.
Check new design of our homepage! Gametophyte and Sporophyte The life cycle of a plant involves the alternation of two generations: However, what is the difference between these phases and what are their distinguishing factors?
Learn about these generations in this BiologyWise article. BiologyWise Staff When you're studying the life cycle of plants, fungi, and protists, you will come across the term alternation of generations. This alternation of generation refers to the alternation of two phases: These generations are phases in the reproduction cycle of the plant.
One is sexual, while the other is asexual. There are several differences between gametophyte and sporophyte stages. Let us have an individual look at them to understand them better.
Sporophyte 2n This phase in the life cycle of a plant is the asexual, spore-bearing generation of the plant, featuring diploid cells. This means the cells of the plant in this generation or phase have two sets of chromosomes in their cells. The zygote or fertilized cell is what conduces to form the sporophyte.
By the process of meiosis reduction divisionthis sporophyte produces haploid spores. Since spores are formed in this generation, the name given to this phase is sporophyte.
The haploid spores produced will then form the next gametophyte generation by growing into multicellular haploid individuals called gametophyte. We learned above that the zygote or fertilized cell is diploid; however, the spores formed by them are haploid.
This takes place because of reduction division or meiosis that takes place. Meiosis is a process in which the number of chromosomes in each cell is cut down to half and the following cells formed will have half the number of chromosomes of their parent cells.
Gametophyte n The other alternating phase in the life cycle of the plant is the gametophyte generation, in which gametes are formed.
This is that phase of the plant in which the gametes, that is the egg and sperm formed are haploid nhaving only one set of chromosomes in them. Thus, gametophyte phase is the sexual, gamete producing stage in the life cycle of the plant.
Spores are actually the first cells of the gametophyte generation. These spores undergo the process of mitosis, by which identical cells with the same number of chromosomes are formed.
Male and female gametes with equal 'n' number of chromosomes are formed.Alternation of Generations Sexual reproduction involves the two alternating processes of meiosis and fertilization. In meiosis, the chromosome number is reduced from the diploid to the haploid number.
In fertilization, the nuclei of two gametes fuse, raising the chromosome number from haploid to diploid. Alternation of Generations A life cycle which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte; characteristic of plants and some algae *Distinguished by haploid and diploid stages that are both multicellular.
A summary of Alternation of Generations in 's The Life Cycle of Plants. Learn exactly what happened in this chapter, scene, or section of The Life Cycle of Plants and what it means. Perfect for acing essays, tests, and quizzes, as well as for writing lesson plans. Characteristics of Bryophytes There are several characteristic features of bryophytes.
First, the green tissue that makes up most of the plant body is not vascularized; it does not have xylem and phloem cells. This absence of specialized tissues for transporting water and dissolved food throughout the organism limits terrestrial forms to being very short .
On-Line Biology Book: GLOSSARY G. Gaia A hypothetical superorganism composed of the Earth's four spheres: the biosphere, hydrosphere, lithosphere, and atmosphere.. gametes Haploid reproductive cells (ovum and sperm).
gametophyte The haploid stage of a plant exhibiting alternation of generations, generates gametes by . Plants exist in alternation generations called sporophytes and gametophytes. Sporophytes represent the diploid phase of plants. Gametophytes represent the haploid phase of plants.