- life cycle
1. Biol. the continuous sequence of changes undergone by an organism from one primary form, as a gamete, to the development of the same form again.2. a series of stages, as childhood and middle age, that characterize the course of existence of an individual, group, or culture.3. any similar series of stages: the life cycle of a manufactured product.[1870-75]
* * *▪ biologyin biology, the series of changes that the members of a species undergo as they pass from the beginning of a given developmental stage to the inception of that same developmental stage in a subsequent generation.In many simple organisms, including bacteria and various protists, the life cycle is completed within a single generation: an organism begins with the fission of an existing individual; the new organism grows to maturity; and it then splits into two new individuals, thus completing the cycle. In higher animals, the life cycle also encompasses a single generation: the individual animal begins with the fusion of male and female sex cells (gametes); it grows to reproductive maturity; and it then produces gametes, at which point the cycle begins anew (assuming that fertilization takes place).In most plants (plant development), by contrast, the life cycle is multigenerational. An individual plant begins with the germination of a spore, which grows into a gamete-producing organism (the gametophyte). The gametophyte reaches maturity and forms gametes, which, following fertilization, grow into a spore-producing organism (the sporophyte). Upon reaching reproductive maturity, the sporophyte produces spores, and the cycle starts again. This multigenerational life cycle is called alternation of generations; it occurs in some protists and fungi as well as in plants.The life cycle characteristic of bacteria is termed haplontic. This term refers to the fact that it encompasses a single generation of organisms whose cells are haploid (i.e., contain one set of chromosomes). The one-generational life cycle of the higher animals is diplontic; it involves only organisms whose body cells are diploid (i.e., contain two sets of chromosomes). Organisms with diplontic cycles produce sex cells that are haploid, and each of these gametes must combine with another gamete in order to obtain the double set of chromosomes necessary to grow into a complete organism. The life cycle typified by plants is known as diplohaplontic, because it includes both a diploid generation (the sporophyte) and a haploid generation (the gametophyte).
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Life cycle — refers to: * Biological life cycle ** Honey bee life cycle * Life cycle of a nation * New product development * Product life cycle management * LIFECYCLE Fundraising * Software life cycle * Adobe LifeCycle … Wikipedia
life cycle — life cycles 1) N COUNT: usu with poss The life cycle of an animal or plant is the series of changes and developments that it passes through from the beginning of its life until its death. The dormant period is another stage in the life cycle of… … English dictionary
life cycle — The term is first recorded in 1873 in its biological meaning ‘the series of changes in the life of an organism’, and this is the only meaning given in the current edition (2006) of the Concise Oxford Dictionary. During the course of the 20c,… … Modern English usage
life cycle — n 1) the series of stages in form and functional activity through which an organism passes between successive recurrences of a specified primary stage 2) LIFE HISTORY (1a) * * * the successive events in the life history of an organism, such as… … Medical dictionary
life cycle — life .cycle n all the different levels of development that an animal or plant goes through during its life … Dictionary of contemporary English
life cycle — life ,cycle noun count 1. ) the series of changes that happen to an animal or plant during its life 2. ) the length of time that something lasts or remains useful … Usage of the words and phrases in modern English
life cycle — ► NOUN ▪ the series of changes in the life of an organism including reproduction … English terms dictionary
life cycle — life cycle. См. жизненный цикл. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) … Молекулярная биология и генетика. Толковый словарь.
life cycle — n. 1. the series of developmental changes in form undergone by a particular type of organism from its earliest stage to the recurrence of the same stage in the next generation 2. any series of changes like this … English World dictionary
life cycle — The lifetime of a product or business, from its creation to its demise or transformation. Bloomberg Financial Dictionary * * * life cycle UK US (also lifecycle) noun [C, usually singular] MARKETING, PRODUCTION ► the series of changes that a… … Financial and business terms