单选题相互易位杂合体在减数分裂的偶线期和粗线期，四条染色体联会常形成的形象是

单选题某染色体各区段的线性顺序是abc.defg，变成了abd.cefg这叫______。 A．中间缺失 B．顶端缺失 C．臂内倒位 D．臂间倒位

单选题Horse thieves, cattle rustlers, bank robbers, train and stagecoach robbers, highwaymen, murderers, these were but some of the criminals who infested the American frontier during the 19th century. In English legend Robin Hood can be considered a bandit, but the outlaws of the Old West were far more violent men and women without any scruples when it came to taking property or life. The careers of many outlaws have been glamorized through fictional accounts of their deeds and their exploits have been the basis for many movie scripts. The era of the American outlaw lasted about 100 years roughly from 1800 to 1900．There had been lawlessness during the Colonial Era. Frontiers have always attracted misfits, failures and renegades who hope to profit by being beyond the reach of government. In the years just before the Revolutionary War, gangs of horse thieves in the back country of South Carolina were broken up by organized bands of farmers called regulators. As frontier settlement expanded rapidly after the Revolution, more opportunities for criminals opened, two common types of bandits were highwaymen and river pirates. Highwaymen accosted people who traveled on foot or horseback, while river pirates preyed upon the boat traffic on the Ohio, Mississippi, and other rivers. Some bandits engaged in both. Criminals in the West gathered momentum with the gold rushes to California, Idaho, Montana, Nevada, and other states. Stagecoaches and trains carrying gold and money became prime targets for bands of outlaws. Bank robberies emerged after the California Gold Rush of 1849 and as prosperity found its way to frontier towns. The first stage robbery was recorded in 1851, and the first train robbery happened in 1866. After the Civil War there was the growth of the cattle kingdom in Texas and neighboring states. Cattle rustling and horse theft turned into significant operations. Range wars bred a great amount of violence. Cattlemen fought over land and water rights, and they fought with great bitterness against sheep farmers. In Texas, range wars were fought over the use of barbed wire to fence grazing land. By the end of the 19th century, the frontier era was past. Major crime shifted to the cities. Ethnic gangs had existed in the slums for decades, preying mostly on their fellow immigrants. With the arrival of Prohibition in the 1920s, an impetus was given to the formation of organized crime as it exists today.

单选题纯种芦花雄鸡和非芦花母鸡交配，得到子一代。子一代个体互相交配，问子二代的芦花性状与性别的关系是 ____ 。

单选题λ噬菌体侵入大肠杆菌细胞后通过______而进入溶原状态。

单选题现代生物进化论认为：种群是生物进化的基本单位；突变、选择和隔离是新物种形成的基本环节。其中新物种形成的必要条件是( )。

单选题在一个E. coli细胞中同时存在两个lac操纵子，其中一个的操纵基因为野生型(Oo)，另一个的操纵基因为组成突变型(Oc)，则 a．由于Oc的存在，Oo不起作用，即不再结合阻抑物； b．由于Oo的存在，Oc无效，即含Oc的操纵子；也不能结合阻抑物； c．两个操纵子互不影响。

单选题 Vienna was one of the music centers of Europe during the classical period, and Haydn, Mozart, and Beethoven were all active there. As the (1) of the Holy Roman Empire (which included parts of present-day Austria, Germany, Italy, Hungary, Czech and Slovakia), it was a (2) cultural and commercial center (3) a cosmopolitan character. Its population of almost 250,000 (in 1800) made Vienna the fourth largest city in Europe. All three (4) masters were born elsewhere, but they were (5) to Vienna to study and to seek (6) . In Vienna, Haydn and Mozart became close friends and influenced each other's musical (7) . Beethoven traveled to Vienna at sixteen to play for Mozart; at twenty-two, he returned to study with Haydn. Aristocrats from all over the Empire spent the winter in Vienna, sometimes bringing their private (8) . Music was an important part of court life, and a good orchestra was a (9) of prestige. Many of the nobility were excellent musicians. Much music was heard in (10) concerts where aristocrats and wealthy commoners played (11) professional musicians. Mozart and Beethoven often earned money by performing in these intimate concerts. The nobility (12) hired servants who could (13) as musicians. An advertisement in the Vienna Gazette of 1789 (14) : " Wanted, for a house of the gentry, a manservant who knows how to play the violin well. " In Vienna there was also (15) music, light and popular in (16) . Small street bands of wind and string players played at garden parties or under the windows of people (17) to throw (18) money. Haydn and Mozart wrote many outdoor entertainment (19) , (20) they called divertimentos or serenades. Vienna's great love of music and its enthusiastic demand for new works made it the chosen city of Haydn, Mozart and Beethoven.

单选题两种噬菌体杂交，如a+b+×a-b-，下列哪种公式可用于计算位点间的重组率______ A．a+b-/(a+b++a+b-) B．a-b+/(a+b++a-b+) C．(a+b-+a-b+)/(a+b-+a-b++a+b+) D．(a+b-+a-b+)/(a+b-+a-b++a+b++a-b-) E．上述答案均不对

单选题在一组杂交试验中，F1只表现母本性状，F2不发生分离，F3世代发生3:1分离，这种现象可能是______。 A．母性遗传 B．母性影响 C．伴性遗传 D．细胞质遗传

单选题人类中的猫叫综合症是由于染色体______造成的。 A．缺失 B．重复 C．倒位 D．易位

单选题已知人类中，棕色眼(B)对蓝色眼(b)为显性，棕色眼与蓝色眼的人结婚，生下的第一个孩子是蓝色眼，则棕色眼人的基因型是______。 A．bb B．BB C．Bb D．无法确定

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