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Topic: Alternation of generations

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  Alternation of generations - Wikipedia, the free encyclopedia
Alternation of generations is a term applied to a reproductive cycle of certain vascular plants, fungi, and protists.
The life cycle of organisms with "alternation of generations" is characterized by each phase consisting of one of two separate, free-living organisms: a gametophyte (thallus or plant), which is genetically haploid, and a sporophyte (thallus or plant), which is genetically diploid.
Kelp are an example of a brown alga with a heteromorphic alternation of generations.
en.wikipedia.org /wiki/Alternation_of_generations   (963 words)

 Life Science | Session 4
Note that, unlike mosses and ferns, water is not required to bring sex cells together and that the embryo develops in a seed, where it is protected from drying-out and is supplied with food.
Alternation of generations in flowering plants is essentially the same as in the conifers (and just as complicated), except that flowers represent the sporophyte.
The main message is this: plant life cycles are unique from animals because of alternation of generations.
www.learner.org /channel/courses/essential/life/session4/closer1.html   (1345 words)

 Biological life cycle - Wikipedia, the free encyclopedia
A life cycle is a period involving one generation of an organism through means of reproduction, whether through asexual reproduction or sexual reproduction.
It exhibits alternation of generations, which features of spore-producing multicellular sporophytes and gamete-producing multicellular gametophytes.
Having multicellular individuals in both phases means that for some seaweeds, it is difficult to determine if a macroscopic specimen is gametophytic or sporophytic unless observed under a microscope, this is called isogamy.
en.wikipedia.org /wiki/Reproductive_cycle   (590 words)

 Kingdom Plantae   (Site not responding. Last check: 2007-11-06)
As such, it is believed that the alternation of generations observed in plants is secondarily derived (i.e., it evolved independently in plants, and was not obtained from a green algal ancestor).
In nontracheophytes, the gametophyte is the dominant generation (=the form you associate with the plant) and the sporophyte grows on the gametophyte.
General structure: Roots present, horizontal stem called a rhizome, “leafy” area called a frond (the broad part is the blade and the “middle” is called the stipe), sporangia are found in groups called sori (meiosis occurs within sporangia), the “juvenile” leaf is called a fiddlehead.
www.colorado.edu /epob/epob1220moreno/Kingdom_Plantae.htm   (848 words)

 Highbeam Encyclopedia - Search Results for Generations   (Site not responding. Last check: 2007-11-06)
Generation of '98 GENERATION OF '98 [Generation of '98] Spanish literary and cultural movement in the first two decades of the 20th cent.
heredity HEREDITY [heredity] transmission from generation to generation through the process of reproduction in plants and animals of factors which cause the offspring to resemble their parents.
Fan's Notes; With his generation turning 60, a critic takes a personal look back at the long, strange trip from Elvis to Eminem and beyond.
www.encyclopedia.com /SearchResults.aspx?Q=Generations   (694 words)

 Lecture 3
This life cycle is therefore diplobiontic (two generations, one haploid, one diploid) with a dominant, free-living gametophyte and an inconspicuous, dependent sporophyte.
The two generations are both free living (diplobiontic), with the sporophyte dominant and the gametophyte inconspicuous.
The 2 N sporophyte is the conspicuous, dominant generation.
nas.cl.uh.edu /novotny/pah03.htm   (1452 words)

 Alternation of generations - Article from FactBug.org - the fast Wikipedia mirror site   (Site not responding. Last check: 2007-11-06)
Alternation of generations is a term usually applied to the reproductive cycle of ferns and fern allies, although it is more correct to say "alternation of phases of a single generation" (see Sporic meiosis lifecycle).
This life cycle is characterized by each generation consisting of two separate, free-living plant bodies: the gametophyte (or haploid) plant and the sporophyte (or diploid) plant.
The conspicuous plant observed in the field as, for example, a fern or clubmoss, is the sporophyte or spore-shedding phase.
www.factbug.org /cgi-bin/a.cgi?a=66535   (436 words)

 SparkNotes: The Life Cycle of Plants: Alternation of Generations
The fluctuation between these diploid and haploid stages that occurs in plants is called the alternation of generations.
In bryophytes (mosses and liverworts), the dominant generation is haploid, so that the gametophyte comprises what we think of as the main plant.
The opposite is true for tracheophytes (vascular plants), in which the diploid generation is dominant and the sporophyte comprises the main plant.
www.sparknotes.com /biology/plants/lifecycle/section1.html   (453 words)

 UCMP Glossary: Botany
alternation of generations -- Life cycle in which haploid and diploid generations alternate with each other.
herb -- Generally any plant which does not produce wood, and is therefore not as large as a tree or shrub, is considered to be an herb.
pteridophyte -- Plant in which the sporophyte generation is the larger phase and in which the gametophyte lives an existence independent of its parent sporophyte.
www.ucmp.berkeley.edu /glossary/gloss8botany.html   (2235 words)

They exhibit life cycles that alternate between a diploid and a haploid form (alternation of generations).
Alternation of generations is most pronounced in plants and algae [ p.
The diploid generation produces haploid spores by meiosis and the cycle repeats itself.
www.personal.psu.edu /faculty/w/x/wxm15/Online/Algology/algology_lec01.htm   (1363 words)

Draw and label (or label a given diagram of) a generalized alternation of generations diagram to show: (a) reproductive stages, (b) the chromosomal condition of reproductive stages, (c) where the meiotic cell division events occur, and (d) where mitotic events occur.
Name/identify the gametophyte generation stages and the sporophyte generation stages in the seed plant alternation of generations life cycle.
State/identify that the seed plant alternation of generations life cycle to have a dominant sporophyte parental stage and identify/name that stage to be the stage that forms the flower(s).
www.colin.edu /science/DL_FOLDER/BIO2313_T8_OBJ-DL.htm   (722 words)

 BRYOPHYTES AND FERNS   (Site not responding. Last check: 2007-11-06)
In the alternation of generations life cycle there are two mature stages known as the sporophyte and gametophyte.
The life cycle of bryophytes is characterized by distinct alternation of generations in which the gametophyte is the dominant stage of the life cycle.
The alternation of generation life cycle is similar to that of the bryophytes, however, the sporophyte generation is the dominant generation in ferns.
www.usd.edu /biol/labs/101/bryo01.htm   (2605 words)

 Ch 12 Life cycles, meiosis and alternation of generations   (Site not responding. Last check: 2007-11-06)
Alternation of generations occurs between diploid and haploid generations.
Diploid (2n) generation: all cells of plant contain a double set of chromosomes.
Haploid (n) generation: all cells of plant contain a single set of chromosomes.
faculty.buffalostate.edu /penaloj/bio115/outline12.htm   (429 words)

 The Haploid-Diploid Life Cycle   (Site not responding. Last check: 2007-11-06)
An alternation of generations defines the haploid-diploid, or 1n-2n, life cycle.
This alternation of generations creates a morphologically complex life cycle, depending on the similarity or dissimilarity of the GPT and SPT, the relationship of these to each other, and the nature of the spores.
There can be an alternation of similar generations, isomorphic alternation of generations, where the GPT and SPT are morphologically identical, except for the reproductive structures.
www.ucmp.berkeley.edu /glossary/gloss6/altergen.html   (296 words)

 Botany online: Energy-Conversion - Multicellular Plants - Sexuality
This alternation is often, though by far not always paralleled by an alternation of generations.
In contrast to an alternation of the nuclear phase, an alternation of generations means not only the zygote or the gametes alone, but a certain vegetative development of the zygote or the spores, too.
The mode of the alternation of generations is an important taxonomic feature of cryptogams and phanerogams.
www.biologie.uni-hamburg.de /b-online/e42/42h.htm   (616 words)

 Lesson Six : Reproduction, Alternation of Generations and Review
An organism that undergoes mitosis of its haploid cells is said to have alternation of generations.
Alternation of generations is more common in "primitive" organisms and is rare in animals.
We use the term "alternation of generations" to describe life cycles that include both haploid and diploid stages that are both multicellular.
www.synapses.co.uk /genetics/reprevw.html   (2319 words)

 alternation of generations
Typical life cycle of terrestrial plants and some seaweeds, in which there are two distinct forms occurring alternately: diploid (having two sets of chromosomes) and haploid (one set of chromosomes).
The diploid generation produces haploid spores by meiosis, and is called the sporophyte, while the haploid generation produces gametes (sex cells), and is called the gametophyte.
The gametes fuse to form a diploid zygote which develops into a new sporophyte;; thus the sporophyte and gametophyte alternate.
www.tiscali.co.uk /reference/encyclopaedia/hutchinson/m0007856.html   (241 words)

 BIL 160 - Alternation of Generations   (Site not responding. Last check: 2007-11-06)
This term reflects the fact that the generations change ploidy, with a diploid generation (the sporophyte) giving "birth" to a haploid generation (gametophte), and that haploid generation giving "birth" to the next diploid generation.
Alternation of Generations: An analogy of the most primitive Alternation of Generations.
If animals were to undergo alternation of generations, then imagine that you are the diploid individual (sporophyte).
www.bio.miami.edu /dana/160/160S04_21a.html   (1011 words)

 Search Results for "Generations"
...The regular alternation of forms or of mode of reproduction in the life cycle of an organism, such as the alternation between diploid and haploid phases, or between...
...whose Commentary on the Generations of Adam is referred to by Sterne in the Sentimental Journey, was Johannes Bevoricius, physician and senator, author of a large...
1.5-23 1 Now these are the generations of the sons of Noah; Shem, Ham, and Japheth: and unto them were sons born after...
www.bartleby.com /cgi-bin/texis/webinator/sitesearch?FILTER=&query=Generations   (302 words)

 Mosses and Liverworts
The leafy shoot of mosses is haploid and thus part of the gametophyte generation.
Mitosis of the zygote produces an embryo that grows into the mature sporophyte generation.
Late in the summer, the calyptra and operculum become detached from the sporangium allowing the spores to be released.
users.rcn.com /jkimball.ma.ultranet/BiologyPages/M/Mosses.html   (530 words)

 New Page 1   (Site not responding. Last check: 2007-11-06)
The alternation of generations means that there are two phases in the life cycle of a plant.
The alternations occur between the gametophyte stage and the sporophyte stage.
The alternation of generations allows for sexual reproduction, and through this mechanism sexual recombination is ensured, which thereby promotes the success of a organism in its perpetually changing environment.
www.personal.psu.edu /users/l/k/lkh145/reproduction.htm   (164 words)

Aquatic and terrestrial environments are not only able to assist or hinder such basic plant functions as photosynthesis, absorption, structural stability and maintenance of an internal aqueous environment, environmental conditions can also assist or hinder reproductive processes and dispersal.
The first is the concept of life cycles or life histories and the second the concept of alternation of generations.
This is an outline of the generalized plant life cycle.
io.uwinnipeg.ca /~simmons/reproduc.htm   (697 words)

 alternation of generations
The stop-spirant alternation in Spanish: converging evidence for a fortition account.
Conceptual and grammatical characteristics of argument alternations: the case of decausative verbs *.
"For her generation the newspaper was a book": media, mediation, and oscillation in Virginia Woolf's Between the Acts.
www.infoplease.com /ce6/sci/A0910169.html   (220 words)

 Chapter 28: Reproduction in Plants   (Site not responding. Last check: 2007-11-06)
Sporophyte is diploid generation in an alternation of generations life cycle.
Gametophyte is haploid generation in an alternation of generations life cycle.
Alternation of generations is modified so sperm does not require water to reach an egg, which
www.sirinet.net /~jgjohnso/apbio28.html   (2275 words)

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