英语生物的Biological life cycle不懂啊,haplontic life cycle diplontic life cycle diplobiontic life cycle (also referred to as diplohaplontic,haplodiplontic,or dibiontic life cycle) These three types of cycles feature alternating haploid and al
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英语生物的Biological life cycle不懂啊,haplontic life cycle diplontic life cycle diplobiontic life cycle (also referred to as diplohaplontic,haplodiplontic,or dibiontic life cycle) These three types of cycles feature alternating haploid and al
英语生物的Biological life cycle
不懂啊,
haplontic life cycle
diplontic life cycle
diplobiontic life cycle (also referred to as diplohaplontic,haplodiplontic,or dibiontic life cycle)
These three types of cycles feature alternating haploid and all germinates.To return to a haploid stage,meiosis must occur (see Cell division).The cycles differ in the product of meiosis,and whether mitosis (growth) occurs.Zygotic and gametic meioses have one mitotic stage and form:during the n phase in zygotic meiosis and during the 2n phase in gametic meiosis.Therefore,zygotic and gametic meiosis are collectively term haplobiontic (single mitosis per phase).Sporic meiosis,on the other hand,has two mitosis events (diplobiontic):one in each phase.
Haplontic life cycle
Zygotic meiosisA zygotic meiosis is a meiosis of a zygote immediately after karyogamy,which is the fusion of two cell nuclei.This way,the organism ends its diploid phase and produces several haploid cells.These cells divide mitotically to form either larger,multicellular individuals,or more haploid cells.Two opposite types of gametes (e.g.,male and female) from these individuals or cells fuse to become a zygote.
In the whole cycle,zygotes are the only diploid cell; mitosis occurs only in the haploid phase.
The individuals or cells as a result of mitosis are haplonts,hence this life cycle is also called haplontic life cycle.Haplonts are:
Most fungi
Some green algae
Many protozoa
[edit] Diplontic life cycle
Gametic meiosisIn gametic meiosis,instead of immediately dividing meiotically to produce haploid cells,the zygote divides mitotically to produce a multicellular diploid individual or a group of more unicellular diploid cells.Cells from the diploid individuals then undergo meiosis to produce haploid cells or gametes.Haploid cells may divide to form more haploid cells,as in many yeasts,but the haploid phase is not the predominant life cycle phase.In most diplonts,mitosis occurs only in the diploid phase,i.e.gametes usually form quickly and fuse to produce diploid zygotes.
In the whole cycle,gametes are usually the only haploid cells,and mitosis usually occurs only in the diploid phase.
The diploid multicellular individual is a diplont,hence a gametic meiosis is also called a diplontic life cycle.Diplonts are:
Animals
Some brown algae
Some fungi,e.g.brewer's yeast
[edit] Haplodiplontic life cycle
Sporic meiosisIn sporic meiosis,the zygote divides mitotically to produce a multicellular diploid "sporophyte".The sporophyte creates spores via meiosis which also then divide mitotically producing haploid individuals called "gametophytes".Gametophytes now produce gametes via mitosis.In many plants the gametophyte is not only small-sized but also short-lived.
In the whole cycle,gametes are usually the only haploid cells,and mitosis usually occurs only in the diploid phase.
Haplodiplonts are:
Most plants
Some fungi
回一楼,复制个屁,要不是我查不到中文的,还要你说废话啊
英语生物的Biological life cycle不懂啊,haplontic life cycle diplontic life cycle diplobiontic life cycle (also referred to as diplohaplontic,haplodiplontic,or dibiontic life cycle) These three types of cycles feature alternating haploid and al
haplontic生命周期
diplontic生命周期
diplobiontic生命周期(也称为diplohaplontic,haplodiplontic,或dibiontic生命周期)
周期这三种功能的交替单倍体和所有发芽.若要返回单倍体阶段,必须在减数分裂(见细胞分裂).不同的周期在减数分裂的产品,以及是否有丝分裂(增长)发生.合子和配子配子数都在合子在减数分裂ñ阶段,第一阶段的有丝分裂和形式:和期间为2n配子减数分裂阶段.因此,合子和配子减数分裂中期haplobiontic统称(每相单丝分裂).Sporic减数分裂另一方面,有两个有丝分裂合子meiosisA合子减数分裂是一个受精卵减数分裂后立即karyogamy,这是两个细胞核融合.此一来,生物结束其二倍体几个阶段,并产生单倍体细胞.这些细胞分裂型子宫的形式,规模更大,多细胞个体,或更多的单倍体细胞.配子相反的两种类型(例如,男性和女性从这些个人或细胞融合)成为受精卵.
在整个周期,受精卵是唯一的二倍体细胞,有丝分裂只发生在单倍体阶段.
个人或作为有丝分裂细胞haplonts结果,因此这个生命周期也被称为haplontic生命周期.Haplonts是:
大多数真菌
一些绿藻
许多原生动物
[编辑] Diplontic生命周期
配子meiosisIn配子减数分裂,而不是分裂meiotically立即产生单倍体细胞,受精卵分裂型子宫产生多细胞二倍体个人或更多的单细胞二倍体细胞群.从个人的二倍体细胞,然后进行米活动(diplobiontic):在每个阶段1
那么长你也好意思贴出来啊?
哪本教科书上复制的吧?整一段就在讲世代交替,你自己找本中文的植物的书,到藻类那一段去找世代交替部分,内容都一样。
大姐,这是英语书上的?