崽崽龙08
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
黄金哇塞赛
Signs of senility, or extreme old age, are seldom seen in the wild. Animals living under natural conditions rarely approach their maximum possible age because of very high death rates due to infant mortality, diseases, predators, bad weather, accidents, or competition for food and shelter. For this reason, most of the reliable information about the length of the life span comes from zoos, where accurate records are kept and animals live under conditions almost ideally suited to prolong life. A mouse whose life is measured in months in the wild can survive years of captivity.Large animals tend to live longer than their smaller relatives -- but there are many exceptions. For example, man is longer-lived than any other mammal. After him, in age, comes the elephant, hippopotamus, horse, rhinoceros, the bears, the big cats and many others which are larger in size. In general, birds live longer than mammals, and certain reptiles the longest of all. A giant tortoise is known to have lived 152 years on the island of Mauritius and then was killed accidentally or it might have lived a century longer. Even our common box turtle rather frequently reaches the 50-year mark. It is an interesting sidelight that there seems to have been no change in the life span of dogs, cats, horses and cows under thousands of years of domestication by man.The following examples of extreme old age have been chosen from the reliable records of zoos and aquariums all over the world.Locally, in the Lincoln Park Zoo, for instance, the Indian elephant, "Judy", died last year at 51. "Bushman", the famous gorilla, died there at 23 years and a pelican at 52. When the Shedd Aquarium was under construction in 1929 workmen, for a joke, stocked the central pool with carp. Twenty Eight years later, three or four of them still survived. Among the native wildlife in our Trailside Museum a gray squirrel has lived 16 years, a barred owl 15, a blue jay and a chipmunk each 12 years. At the Brookfield Zoo, the pair of chimps, "Mike" and "Sally" died at 35 and 37 years old, respectively. They still have the same alligator snapper and "Cookie" the Cockatoo with which they opened in 1934. Dozens of birds have lived 18 to 20 years and hundreds 8 to 15 years. A spitting cobra died after 23 years in the zoo.
