单选题下面是关于现代生物进化理论的叙述，其中不正确的是( )。

单选题有两个细菌品系，它们合成三种氨基酸的能力不同，以a+b+c+为供体和受体a-b-c-杂交。杂交后，取细菌的悬浮液分别涂在补充了氨基酸A、B和C的培养基上，观察到在一种平板上有四种细菌菌落，然后把此菌落影印到各种平板上(如图所示)根据上述资料，下列有关各菌落基因型的阐述哪句话正确______A．菌落②的基因型一定是a-b+c-B．菌落③的基因型一定是a+b+c+C．菌落④的基因型一定是a-b-c-D．上述答案均对

单选题"The imperative to self-knowledge has always been at the heart of philosophical inquiry," wrote MIT professor Sherry Turkle in the insightful book about the web and the self, Life on the Screen: Identity in the Age of the Internet. Published in 1995 as the second part of a trilogy that examined our relationships with technology, it looked at how we are who we are in online spaces. And what that means for us offline. The good news is that the results are positive: "Play has always been an important aspect of our individual efforts to build identity," she said, referencing developmental psychologist Erik Erikson, and nodding to the theories of psychoanalysts Freud, Lacan and Jung. "In terms of our views of the self," she wrote, "new images of multiplicity, heterogeneity, flexibility, and fragmentation dominate current thinking about human identity. " At the time Life on the Screen was released, most of the visitors were college students and their professors from a remarkably small talent pool, and a surprisingly small geography. They were tech-savvy, and generically open-minded about the new fields of virtual exploration that lay within the networks of this new communication platform. They were, in other words, liberal, enlightened types who were more willing to embrace the unprecedented fluidity of self-expression that this new technology uniquely afforded. As a psychoanalyst and a web user herself, Turkle spent much of the book explaining why the articulation of multiple personalities wasn't pathological. Contrary to its Latin root, identity need not mean "the same", she argued. "No one aspect can be claimed as the absolute, true self", she wrote, maintaining that the web allowed us the opportunity to get to know our "inner diversity". In the great psychoanalytic tradition, she said that self-actualisation meant coming to terms with who we are, and integrating each aspect of it into a coherent and well-integrated us. Almost everyone has experienced this kind of identity play. Even if you've never ventured into an online game or been a signed-up member of a web community, you've probably developed a profile for a social network, written a blog, styled a website, commented on an article. But things are different from the time when Turkle was writing Life on the Screen. Nowadays, our virtual social lives are increasingly integrated. with our offline social lives. The freedom of expression is curtailed by the threat of offline consequences from online actions. Today, your reputation offline is far more closely tied to your reputation online than before. In fact, our experience of contemporary identity online is disarmingly similar to offline. However, I still subscribe to the old Turkle. Consequence-free online environments allow us to practise and play without fear of offline effect, and offer an extraordinary place to experience the fluidity of our selves: I can be anyone, even a dog. As Tom MacMaster found, there still are places online where this is possible.

单选题一个处于平衡状态的植物群体中的白化苗的频率约是4×10-4，白化基因是隐性的，那么表现型正常的植株后代中出现白化苗的频率是()。

单选题在一个突变过程中，一对额外的核苷酸插入DNA内，会有什么样的结果? (a)完全没有蛋白产物；(b)产生的蛋白中有一个氨基酸发生变化； (c)产生的蛋白中有三个氨基酸发生变化； (d)产生的蛋白中有两个氨基酸发生变化； (e)产生的蛋白中，插入部位以后的大部分氨基酸都发生变化。

单选题小鸡中，两对独立遗传的基因控制着羽毛色素的产生和沉积，在一个位点上，显性基因可产生色素，隐性基因则不产生色素；在另一位点上，显性基因阻止色素的沉积，隐性基因则可使色素沉积。小鸡羽毛的着色，必须能产生并沉积色素，否则为白色毛。如果一表现型为白色的鸡(两位点均为隐性纯合体)和另一种表现型为白色的鸡(两位点均为显性纯合体)进行杂交，F 2 代中羽毛着色的频率为______

单选题在某些昆虫的幼虫中，多线染色体产生的原因是：______。 A.一条染色体发生断裂，与同一条染色体的另一部位重新连接 B.在染色体复制之前，细胞分裂发生了几次 C.染色体发生了复制，但没有发生相对应的核分裂 D.在进行非等位交换时，一条染色体的一小部分发生了复制

单选题除了达尔文之外，另一个人提出了与自然选择相同的学说，是推动进化学的主要力量，他把自己的学说告诉了达尔文，促使达尔文的“物种起源”学说的传播。这个人是谁?( )

单选题小麦为异源六倍体作物，其x=7。所以他的单体系列可以有______种类型。 A．42 B．28 C．21 D．7

单选题玉米n+1花粉不育，n+1胚囊则可育。已知R产生红色，r无色。在杂交RRr♀×rr♂中子代的表现型比例是______。 A．1红色:1无色 B．3红色:1无色 C．5红色:1无色 D．6红色:1无色

单选题很相似但不同种的鱼把卵细胞和精子排放在同一水域中，其中一种鱼的精子不能进入另一种鱼的卵细胞内。这是由于下列哪种原因所引起的?( )

单选题The cultured E. coli system was infected by two types of bacteriophages. One type is a-b-, another is a+b+. Then the lysate was sampled and smeared on medium. The data of the bacteriophage growth by counting plaques is as follows: a+b+=4750, a+b-=370, a-b+=330, a-b-=4550. How much is the recombination rate between a and b? ______ A．70% B．12.8% C．7% D．15%

单选题让Hfr arg- leu+ azis strr与F- arg+ leu- azir strs混合培养，使其发生接合，想增多F-重组型arg+ leu+ azir的出现，下面哪一种培养基将完成这个选择?______。 A．具有str的基本培养基 B．具有azi的基本培养基 C．具有leu和azi的培养基 D．具有str azi的基本培养基

单选题When two of the world's richest and mightiest men pledge to destroy an enemy, it is time to pay attention. Bill Gates, the former boss of Microsoft who now devotes all his time to his charitable foundation, travelled this week to New York, the city run by Michael Bloomberg, to join his fellow billionaire's campaign to stamp out smoking. Have the two potentates met their match? Despite decades of work by health campaigners, more than one billion people still smoke today. Smoking kills up to half of those who fail to quit puffing, reducing their lives by an average of 10 to 15 years. The World Health Organisation (WHO) says more than 5 million people a year die early from the effects (direct or indirect) of tobacco. That exceeds the combined toll of HIV/AIDS, tuberculosis and malaria. Despite that dismal situation, there are three reasons to give the latest pair of campaigners a slim chance of success: money, methods and motivation. Messrs Gates and Bloomberg vowed to spend a combined total of $ 500 million on discouraging the weed. Since Mr. Bloomberg's charity had already announced an award of $125 million earlier, the new money pledged this week totalled a "mere" $ 375 million: $ 250 million from the mayor, and a fresh $ 125 million from the software magnate's philanthropic outfit. How will this cash be spent? In quite innovative ways, and that is a second reason for optimism. Hitherto, most anti-smoking funds have been channelled through a few large bureaucracies. But Mr. Bloomberg's charity wants to let a thousand flowers bloom: in other words, to lend a hand to many initiatives, both public and private, to see what works. There will be a competitive grant scheme for poor countries where the tobacco habit is spreading. The very fact that two giants are teaming up is a landmark in American philanthropy- comparable to Warren Buffett's decision, two years ago, to put his fortune at the disposal of Mr. Gates' foundation. As part of their joint commitment, Mr. Gates is giving some of his $ 125 million directly to Mr. Bloomberg's charity; the rest will go to carefully monitored projects in India, China and other places where the number of smokers is rising relentlessly. Then there is motivation. There are other big players in this cause, and that should induce every new entrant to try bringing something fresh to the party. Earlier this year the WHO started a campaign against tobacco known as MPower. One of its selling points was that in contrast with many other projects, it had a fairly clear idea about what was needed. WHO experts have listed a series of tactics, ranging from aggressive public education to a rise in tobacco taxes, that deliver results. (Even if high taxes lead to some smuggling and diversion, studies done in Brazil, for example, show that fiscal measures do curb consumption. ) The World Bank, which funded that research, is also thought to be ready to join the anti-smoking scrum after years of paying little attention. A crowded field, indeed. But having an extra $ 500 million from two hard-driven billionaires surely won't hurt.

单选题以病毒颗粒为载体将遗传物质从一个细胞转移到另一个细胞的过程称为 ____ 。

单选题入噬菌体侵入大肠杆菌细胞后通过( )而进入溶源状态。

单选题对达尔文自然选择学说的正确评价是( )。

单选题下列有关种群的叙述中，不正确的是( )。

单选题家猫中，如果一个决定条纹毛色的常染色体显性基因外显不全，但其表现度稳定，下面的描述哪句正确______

单选题A female-male mosaic fruit fly may be formed, if there is chromosome loss or______． A．equal division during sperm generation B．abnormal mitosis during merogenesis(fertilized egg cleavage) C．meiosis in embryo D．meiosis when sperm is tailed