单选题老鼠中，毛色基因位于常染色体上，黑毛对白毛为完全显性，如果白毛与黑毛杂合体交配，子代将显示______

单选题下表所列举的A、B、C、D鸟中，哪种鸟将得到更多的进化优势? 鸟 数目 产卵 孵出 繁殖后代 A 9 8 2 B 2 2 2 C 9 9 3 D 7 5 1

单选题某植物中，花色是由一对呈中间显性的基因控制的，一种纯合体为深蓝色花，另一种纯合体为白花，杂合体为浅蓝色花。如果深蓝花与浅蓝花进行杂交，其子代的表型为______

单选题质核互作雄性不育系的遗传结构为( )。

单选题果蝇多是有翅的，但后来产生了残翅的类型，这些类型的个体在森林中难以生存，但在海岛上去生活得很好，这说明( )。

单选题姊妹染色单体是在细胞周期的______期形成的。 A.前期 B.中期 C.末期 D.间期

单选题睾丸女性化是( )。

单选题豌豆中，高茎(T)对矮茎(t)为显性，黄子叶(Y)对绿子叶(y)为显性，假定这两个位点的遗传符合孟德尔第二定律，若把真实遗传的高茎黄子叶个体与矮茎绿子叶个体进行杂交，F 2 代中矮茎黄子叶的概率是______

单选题下面是关于红色脉孢霉(Neurospora crassa)遗传分析的陈述，请选择最佳选项。______ A．由于红色脉孢霉的子囊狭窄，减数分裂后的4个同源染色体在子囊中顺序排列 B．作为细菌遗传分析的模式物种，红色脉孢霉可以利用着丝粒作图法进行基因定位 C．在红色脉孢霉中，减数分裂第二次分裂(MⅡ)的比例可用于计算某基因位点与着丝粒的重组率 D．由于红色脉孢霉的子囊狭窄，减数分裂后的4个染色单体在子囊中顺序排列

单选题转座作用前后DNA的含量变化是： ____ 。

单选题The inheritance pattern of dimple is dominant. A man with dimples who was married by a woman without dimples gave birth to 8 children, and interestingly, all the eight children have dimples in their faces. The most possible genotype of this man is______． A．Aa B．AA C．aa D．unable to be inferred

单选题细菌中，同源重组发生在一些热点周围，这和 ____ 在chi位点上的单链内切酶活性有关。

单选题George Williams, one of Scottsdale's last remaining cowboys, has been raising horses and cattle on his 120 acres for 20 years. The cattle go to the slaughterhouse, the horses to rodeos. But Mr. Williams is stomping mad. His problems began last year when dishonest neighbours started to steal his cattle. Then other neighbours, most of them newcomers, took offence at his horses roaming on their properties. Such grumbles are common in Arizona. The most recent Department of Agriculture census shows that 1 213 of Arizona's 8 507 farms closed down between 1997 and 2002. Many cattlemen are moving out to remoter parts of the state. Doc Lane is an executive at the Arizona Cattlemen's Association, a trade group. He says Arizona's larger ranch owners are making decent profits from selling. It is the smaller players who are the victims of rising land values, higher mortgages and stiffer city council rules. What happens all too often is that people move in next to a farm because they think the land pretty. But soon they start complaining to the council. In Mr. Williams's case it was the horses that annoyed them. Other newcomers don't like the noise, the pesticides and the smell of manure. Locals worry about the precious, dwindling cowboy culture. Arizona's tourism boards like to promote a steady interest in all things about cowboy and western. Last year more British and German tourists came than usual, and many of them were looking precisely for that. Arizona's Dude Ranch Association fills its $ 350-a-night luxury ranches most of the year; roughly a third of the guests are European. Many of the ranchers themselves see all this tourism as a cheeky attempt to commercialise a real and vanishing culture. In Prescott, estate agents promote "American Ranch-style" homes with posters of horse riders. On the other side of the street is Whiskey Row, a famous strip of historic cowboy bars. But in Matt's Saloon on Saturday night, real cattlemen could not be found. Farm folk like Mr. Knox and Mr. Williams are weighing up their options. Many will migrate to remoter places where land is cheaper and not crowded with city people. Younger ones take on side-jobs as contractors and are cattle-hands part-time. Older cowboys aren't sure what to do.

单选题具有一对杂合基因的个体连续自交______代，才能使约97%的个体纯合。 A．3 B．5 C．6 D．7

单选题群体概念的含义是( )。

单选题____ 可以促进非严格配对的两段DNA发生重组。

单选题达尔文生物进化学说的中心内容是( )。

单选题These are hard times for Deutsehe Bank, despite its huge strides in investment banking. Next week its chief executive, Josef Ackerman, goes on trial in Dusseldorf. Careless words by Rolf Breuer, the head of its supervisory board, led to another court ruling last month that may cost Germany' s biggest bank several hundred million euros in damages. Then there is Parmalat. Although no evidence has emerged of complicity in the Italian dairy group' s fraud, Deutsche' s name has become entwined in the affair. In many other respects, however, Deutsche' s reputation has never been higher. In dubbing it " Bank of the Year 2003", International Financing Review, the capital markets' favorite newssheet, purred that Deutsche was a "lean, aggressive, focused universal bank" In the league tables that investment banks watch so keenly, Deutsche excelled last year as lead manager of bonds and convertible bonds and of some racier products, such as repackaged debt securities and high-yield "junk" bonds. In other disciplines it rarely fell below the top ten in the world. However, it is still nowhere near the top in equity offerings and advice on mergers and acquisitions, except in Germany. It still has a problem with costs,which were a fat 82% of income in the third quarter of 2003, thanks mainly to the thick pay packets of its investment bankers and its poor returns from corporate and retail banking. Mr. Ackermann must try to improve the weak spots while spending two clays a week, probably until June, in a courtroom. He and four others face charges of "breach of trust" over the way bonuses were awarded to board meinbers of Mannesmann, a telecoms company. Mr. Aekermann sat on Mannesmann' s supervisory board. There is no suggestion that he gained personally. Nor was there any harmful intent in Mr. Breuer' s remarks in a television interview about the financial health of the Kirch media group shortly before its bankruptcy. But he was careless, and a Munich court found Deutsche (but not Mr. Breuer) liable for damages, to be set in due course, without right of appeal. The bank said this week it has lodged a protest with the federal supreme court in Karlsruhe. Meanwhile, Kirch has filed a suit against Deutsche in America. Deutsche's involvement with Parmalat also looks sloppy. It led a 350m bond issue fur the group in September. It was also a leading borrower and lender of Parma[at shares, so that in November it technically held the voting rights to over 5% of Parmalat stock. That stake had fallen to 1.5% by December 19th, the day the dairy company's black hole became public. It reported this, perhaps over-zealously, to the Italian authorities. That may have given the wrong impression, say, sources close to the bank, because the transactions were for third parties. This is awkward for a bank that managed to avoid most serious attacks on conflicts of interest thai beset the investment-banking industry following the collapse of Enron in 2001 and the bursting of the tech-stock bubble. Mr. Ackermann will need a clear head to steer the bank through the coming storms.

单选题两个都是黑尿症基因携带者的男女结婚(黑尿症属单基因常染色体隐性遗传)，他们的孩子患黑尿症的概率是______

单选题在一个细菌品系中，已知三位点的顺序可能是a-b-c也可能是a-c-b。为了确定其中之一，做了两次杂交，并选出a+b+c+重组体，当时发现杂交Ⅰ(供体a+b+c×受体abc+)和杂交Ⅱ(供体abc+×受体a+b+c)，都得到等量的+++重组体，从这些结果看，三位点的顺序可能性较大的是______ A.顺序是cab B.顺序是abc C.顺序是acb D.顺序未知，这是因为交配方式是互交，虽有等量的+++重组体，但未提供确定顺序的信息