单选题我国的杂交水稻主要是在袁隆平教授的主持下研究成功。他提出了通过选育水稻______，利用水稻的杂种优势，打破了“水稻等自花授粉作物没有杂种优势”的传统观念，丰富了遗传育种理论和技术，具有很高的学术价值。 A．雄性不育系、雄性不育保持系、雄性不育恢复系的三系法途径。 B．雄性不育系、雄性可育系、雄性不育保持系的三系法途径。 C．雄性不育系、雄性可育系的二系法途径。 D．雄性不育保持系、雄性不育恢复系的二系法途径。

单选题 通过杂交的方法，用DNA的一个片段去寻找一个基因，这个片段被称为 A、载体； B、探针； C、限制片段； D、反转录病毒。

单选题在一株基因型为Dd的西红柿上，人工诱导出一个四倍体枝条。该枝条上的生殖器官所产生的可能的配子有______。 A．4种(DD、dd、DDd、Ddd) B．4种(DD、dd、D、d) C．2种(DDd、Ddd) D．7种(DD、Dd、dd、DDd、D、d、Ddd)

单选题 Meselsen和Stahl的实验证明DNA复制是： A、全保留式 B、散乱模式 C、半保留式 D、其他复制方式

单选题雄鹿往往用鹿角作为争夺配偶的武器，所以它的鹿角发达。按达尔文的观点，鹿角发达的原因是( )。

单选题 关于质量性状的描述，错误的是（ ）。 A、其变异表现有分离、自由组合和连锁关系 B、其遗传变异表现为正态分布 C、一个基因座存在有显隐性两个基因 D、随着参与决定性状的基因数的增加，后代表型逐渐趋于正态分布

单选题有一个水稻不育系与恢复系杂交，然后让F1自交，结果发现其F2群体分离出不育株和可育株，比例为1:3；用大量品种与不育株测交，有的测交组合后代全部植株均不育。则其不育系类型为______。 A．孢子体不育 B．配子体不育 C．核不育 D．质不育

单选题以青霉素培养基做为选择培养基，用来筛选细菌的营养缺陷型，这一技术的原理是______ A．青霉素可杀死敏感型细菌，只允许抗性型细菌在上生存 B．青霉素有时可补偿营养缺陷型，允许营养缺陷型细菌在基本培养上生存 C．青霉素在营养缺陷型的菌落特征上，起明显的修饰作用，便于人们观察认识 D．青霉素可杀死繁殖的原养型细菌，只留下营养缺陷型

单选题有人观察到玉米籽粒的一些性状(如籽粒颜色、紫色糊粉层、甜粒等性状)每年都以同样的频率发生相同的突变，这可以认为是突变的______。 A．重演性 B．平行性 C．可逆性 D．多方向性

单选题As with many a grown-up sporting star, the first hint of greatness came at an early age for Lewis Hamilton. As an eight-year-old at his first kart race, he charged "more like a mature driver than a novice," remembers Martin Hines, owner of the Zip Kart racing company. Scything his way through the field just outside London, Hamilton had a confident style that seemed different from normal rookies, Hines says. "There was a little spark about him." Now 22, and in his debut season in Formula One—he became the first black driver to make it onto the grid in motor racing's blue-ribbon championship. His success and profile that have earned young Hamilton comparisons with other sporting greats. His color— Hamilton's grandfather came to Britain from Grenada in the 50s—and the positive influence of his father, Anthony, have drawn parallels with Tiger Woods. Hamilton acknowledges that his participation could stoke interest among ethnic groups who may not be into the sport now. "Hopefully people that can relate to me will see that it's possible and also try to get into the sport," he told the BBC. Moreover, his youth, good looks and wholesome image are also likely to get marketers fired up. Countless more karting titles followed before 2001. He "made seasoned drivers look silly," says Tony Shaw, Hamilton's then team manager at Manor Motorsport. Hamilton's raw, natural speed and canny race craft nudged him closer to the big leagues. Hamilton's "understanding of when and where to overtake and how to take advantage of a situation is very advanced," Shaw says. At his first crack at GP2, the training ground for Formula One, Hamilton dominated the 2006 season with a series of blistering drives on his way to the title. Hamilton is "not worried about showing or doing what he's used to doing just because it's Formula One," says Hill. For many new drivers, "that's an enormous hurdle." With the retirement last year of seven-time world champion Michael Schumacher, there's one less rival for Hamilton to negotiate. And Hamilton is certainly not short on confidence. When he first met Ron Dennis—now his Formula One team boss—as a 10-year-old in a borrowed suit, Hamilton promptly told him he wanted to drive for McLaren. Three years later, he joined the team's support program for promising young drivers. But, say former team managers, he's ready to listen and learn when things go wrong. Hamilton has a rare "capacity to question himself—to analyze very clearly after a race," says Frederic Vasseur, general manager at the ART Grand Prix team behind Hamilton's GP2 championship. As for whether he'll become the Tiger Woods of the sport, it's too early to know whether he can live up to those standards. But for now, his fans are bullish. Damon Hill was the last British driver to take the world crown. And it's Hamilton, Hill says, "who looks likely to be the next./

单选题玫瑰冠与胡桃冠鸡杂交后代产生15只胡桃冠、14玫瑰冠、5只豌豆冠、6只单冠。已知纯种玫瑰冠与纯种豌豆冠鸡杂交后代是胡桃冠鸡，请选择

单选题纯种芦花雄鸡和非芦花母鸡交配，得到的子一代相互交配，子二代(F2)表现：______。 A．1/2芦花(♂)，1/2芦花(♀) B．1/2非芦花(♂)，1/2非芦花(♀) C．3/4芦花(♀♂)，1/4非芦花(♀♂) D．全为芦花(♂)，1/2非芦花(♀)1/2芦花(♀)

单选题两个基因A、B通常相距38cM，却在某生物染色体的同一臂上。在这38cM的区域内，大约有1/3的长度是一个臂内倒位。但这个倒位不包括这两个基因座。如果该植物是臂内倒位杂合子，这两个基因间的重组率如何?______。 A．大于38cM B．等于38cM C．小于38cM D．不能确定

单选题细菌中各种mRNA所编码的蛋白质数目常有差异，据此有monocistronic，polycistronic和intereistronic之分。多数mRNA是 a．monocistronic mRNA； b．polycistronic mRNA； C．intercistronic mRNA。

单选题一个AB血型的男人与一个B血型的女人结婚，生了4个孩子，第一个是AB型，第二个为O型，第三个为AB型，第四个为A型。后来，由于夫妻不和，丈夫提出离婚，声称经血型家系分析，他不可能是所有孩子的父亲，他说的有道理吗?______