问答题gene pool

问答题动原粒(kinetochore)

问答题植物Lychnis alba是雌雄异株。把阔叶雌株与窄叶雄株杂交，得到的F 1 代雌雄植株都是阔叶的，但F 2 雄性植株有两种类型——阔叶和窄叶，你怎样解释?哪一个性别是异配性别(XY)，哪一个性别是同配性别?

问答题如果某个生物的二倍体个体染色体数目为16，在有丝分裂的前期可以看到多少个染色单体?在有丝分裂后期，有多少染色体被拉向细胞的每一极?

问答题如何判断某一性状是由常染色体上基因控制的性状遗传还是由X染色体上基因控制的遗传?

问答题(46) Many journalism critics have recently argued that American journalism is undergoing a profound change because it now regularly mixes entertainment with the news. Critics typically argue that this entertainment is in the form of sensationalistic celebrity-scandal. In fact, there is a long history of sensationalism in American journalism, a fact documented by several journalism historians. (47) But the main point of contemporary critics is that sensationalism and tabloid-style techniques, which were always present on the fringes of journalism, are now becoming the norm in American journalism, and are being adopted by so-called "mainstream" media as part of economic survival strategies in the cutthroat business climate of American mass media. These contemporary critics typically argue that there should be a rigid boundary between mainstream journalism and other kinds of mass communication such as tabloid journalism. (48) The critics imply that one kind of communication is more legitimate in certain contexts than the other, and even that tabloid journalism is not journalism at all but is instead entertainment. One of the claims made by mass media critics is that journalism just recently got worse. But this may be a perennial complaint. (49) A quick review of journalism criticism reveals that the argument that journalism used to be better but just recently got worse is common throughout the history of journalism. The critiques usually say that journalism used to make bold distinctions between news and entertainment but now combines the two. These critiques construct the logical conclusion that journalism has steadily declined in quality over many years. (50) Taken together, the criticisms add up to the conclusions that the people who used to do journalism were better and had higher standards than those of today and that the distinctions between news and entertainment used to be greater. Examples of this critique can be found in even the earliest discussions of American journalism. For instance, critics panned Benjamin Day's New York Sun of the early 1830s because it often contained humor and sensational news of suicides. Similarly, some critics hated James Gordon Bennett's New York Herald of the mid-to late-1830s because it contained entertaining satirically written police court reports, as well as in-depth crime stories. Bennett pioneered the "human-interest story" or feature story when he wrote in vivid detail in 1836 about the grisly murder of the prostitute Helen Jewett, quoting her madam and describing Jewett's apartment in minute detail. Bennett's day-by-day narrative of the ensuing sensational trial reminds us of how journalism and entertaining literature have been combined for many years to make newsworthy stories "more palatable for consumption. " Bennett was soundly criticized by his competitors and others for blurring the boundary between journalism and entertainment. His detractors, many of them his competitors, waged what they called a "Moral War" in the late 1830s against Bennett and his enjoyable but sensationalistic newspaper. They maintained that Bennett was a "deviant" journalist because he blurred the boundaries of journalism by making his newspaper entertaining and popular. Those running the "Moral War" against Bennett were unsuccessful at running him out of the journalism business, but they did seriously wound his business.

问答题简要说明你所知道的性别决定机制。

问答题假定某材料的VE=20，VA=20，VD=20，试计算该性状的广义遗传力和狭义遗传力。

问答题transposon; retrotransposon

问答题假定在某植物群体中，基因Q在遗传上是平衡的，如果它的等位基因q以纯合体(qq)出现时占其群体总数的49%，请问Q基因在配子及合子中的比例是多少?

问答题举例说明在同源染色体中的异源区段不对称碱基对有哪几种可能的修复方式?

问答题简述原核生物与真核生物基因组的区别。

问答题下列家系是由A基因决定的某一人类的显性性状，正常个体是aa，暗色表示含有A基因的基因型个体，白色表示正常个体。

问答题简述受精素的作用和受精的完成。

问答题简述性染色体和常染色体的异同点。

问答题一个果蝇家系，对隐性体细胞等位基因a、b、c是纯合的，这3个基因以a、b、c的顺序连锁。将这种雌性果蝇与野生型雄性果蝇杂交，得到F1，再让F1的杂合子之间相互杂交，得到F2的结果如下： + + + 1365 a + + 47 a b c 365 + b c 44 a b + 87 a + c 5 + + c 84 + b + 4 请问： (1)基因a与基因b，基因b与基因c，基因a与基因c它们之间的重组频率各是多少? (2)双交换与并发系数是多少? (3)作出连锁图。

问答题外源性哮喘在某地区的发病率为0.6%，有人在75名患者的亲属中调查，发病情况如下： 患者亲属 总 数 发病个体 父 母 150 5 同 胞 238 8 子 女 37 5 试估计此病与遗传有关?如果是遗传的，是单基因遗传还是多基因遗传?如果是多基因遗传，试估算遗传度(力)。

问答题假定你研究噬菌体φX174 DNA，发现其碱基组成为A，25%；T，36%；G，24%；C，18%。(1)这符合碱基当量规则(chargaffs rule)吗?(2)你如何解释这一结果?(3)该噬菌体是如何复制的?

问答题某小麦群体中，染病性植株(rr)有9%，抗病性植株(RR或Rr)为91%。抗病性植株可正常生长、开花和结实。而染病性植株的幼苗致死。经三代随机交配后，该小麦群体中染病性植株的百分比是多少?

问答题为何说孟德尔分离法则具有普遍意义?分离比实现的条件有哪些?