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Alternation of generations

Definition of the noun alternation of generations

What does alternation of generations mean as a name of something?

noun

  1. the alternation of two or more different forms in the life cycle of a plant or animal

Explanation

Alternation of generations is a term primarily used to describe the life cycle of plants. A multicellular gametophyte, which is haploid with n chromosomes, alternates with a multicellular sporophyte, which is diploid with 2n chromosomes, made up of n pairs. A mature sporophyte produces spores by meiosis, a process which reduces the number of chromosomes to half, from 2n to n. Because meiosis is a key step in the alternation of generations, it is likely that meiosis has a fundamental adaptive function. The nature of this function is still unresolved, but the two main ideas are that meiosis is adaptive because it facilitates repair of DNA damages and/or that it generates genetic variation.

Printed dictionaries and other books with definitions for Alternation of generations

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Google previewWorks (1910)

by Herbert Spencer

Alternation of generations is a means of furthering multiplication. To be effective each member of either generation must be a self-supporting centre of growth or diffusion or both. Hence if, as in the Liverworts, one of the so-called alternating ...

Google previewThe Dual Nature of Life (2005)

Interplay of the Individual and the Genome by Gennadiy Zhegunov

The alternation of generations is a striking phenomenon that is characteristic only of communities of living organisms, and it is an amazing property peculiar to life. It started from the moment of the origin of living bodies and it continues to this ...

Google previewPolyploidy (2012)

Biological Relevance by Walter H. Lewis

do not transform to sexual allopolyploids with n and 2n alternation of generations is an interesting question. Gymnosperms.

Google previewA Complete Course in ISC Biology (1997)

by V. B. Rastogi, B. Kishore

Alternation of generations is a regular feature in the life cycle of a multicellular plant where a gamete-bearing haploid gametophytic generation alternates with the spore-producing diploid sporophytic generation.

Google previewWorks: Principles of biology (1899)

by Herbert Spencer

Alternation of generations is a means of furthering multiplication. To be effective each member of either generation must be a self-supporting centre of growth or diffusion or both. Hence if, as in the Liverworts, one of the so-called alternating ...

Google previewInvertibrate Zoology (2001)

by P.S.Verma

The term alternation of generations means that the individual exists in two distinct forms, which alternate each other regularly in the life history. One individual possesses the power to reproduce the other by asexual reproduction, which again ...

Google previewe-Study Guide for Campbell Biology in Focus, textbook by Lisa A. Urry (2013)

Biology, Biology by Cram101 Textbook Reviews

Alternation of generations: Alternation of generations is a term primarily used to describe the life cycle of plants (taken hereto mean the Archaeplastida). A multicellular sporophyte, which is diploid ...

Google previewThe Synthetic Philosophy of Herbert Spencer: Principles of biology (1899)

by Herbert Spencer

Alternation of generations is a means of furthering multiplication. To be effective each member of either generation must be a self-supporting centre of growth or diffusion or both. Hence if, as in the Liverworts, one of the so-called alternating ...

Google previewBiology 2e Teachers Manual: Search for Order in Complexity (2007)

by Ed Shewan

An alternation of generations is a type of life cycle in which the asexual reproductive stage alternates with the sexual reproductive stage. 3. Answers may vary. The student is asked to name one positive and one negative ecological effect of the ...

Google previewE-Book for Life: the Science of Biology (2013)

by David E. Sadava, H. Craig Heller, Gordon H. Orians, William K. Purves, David M. Hillis

Alternation of generations is a feature of the life cycles of many multicellular protists, all land plants, and some fungi. In these life cycles, a multicellular, diploid, spore-producing stage gives rise to a multicellular, haploid, gamete- producing ...

Google previewEncyclopedia of Biology (2009)

by Don Rittner, Timothy Lee McCabe

alternation of generations A life cycle in plants where there is both a multicellular diploid form (the sporophyte generation) and a multicellular haploid form (the gametophyte generation). Gametophytes produce haploid ...

Google previewThe American Heritage Science Dictionary (2005)

by American Heritage Dictionary

alternation of generations (ol'tar-na'shan) The regular alternation of forms or of mode of reproduction in the life cycle of an organism, especially the alternation between sexual and asexual reproductive phases in ...

Google previewDictionary of Invertebrate Zoology --Paperback (2010)

by Maggenti Mary Ann, Maggenti Armand, Gardner Scott

Form of reproduction that has sexual and asexual or parthenogenetic forms; alternation of generations; xenogenesis. see metagenesis. heterogenetic a. [Gr. heteros, different; genesis, descent] ...

Google previewThe Facts on File Dictionary of Biology (2009)

by Robert Hine, Daintith

alternation of generations The occurrence of two, or occasionally more, generations during the life cycle of an organism. It is found in some animals, e.g. certain parasites and hydrozoan ...

Google previewThe Facts on File Dictionary of Evolutionary Biology (2009)

by Elizabeth Owen, Eve Daintith

alternation of generations The occurrence of two, or occasionally more, generations during the life cycle of an organism. It is not found in animals, ...

Google previewA Dictionary of Entomology (2011)

An alternation of generations which involves a sexual and a parthenogenetic generation.

Google previewNew International Encyclopedia (1914)

It is to mosses and ferns, therefore, that one must go for the clearest examples of alternation of generations. In an ordinary moss the gametophyte consists of the well-known leafy moss plant, which bears sex organs at the tips of its main 6tem ...

Google previewA Dictionary of Plant Sciences (2012)

by Michael Allaby

alternation of generations An alternate development of two types of individual in the *life cycle of an organism. Usually one type reproduces asexually and the other sexually. (The term is often ...

Google previewThe Facts on File Dictionary of Botany (2002)

by Jill Bailey

alternation of generations The occurrence of two, or occasionally more, generations during the life cycle of an ...

Google previewA Dictionary of Biology (2015)

by Elizabeth Martin, Robert Hine

alternation of generations The occurrence within the *life cycle of an organism of two or more distinct forms (generations), which differ from each ...

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Alternation of Generations

Red Algae showing alternation of generations.

Photo credit: jkirkhart35

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