单选题用达尔文的自然选择学说，来判断下列叙述中正确的是( )。

单选题两个植物杂交，它们的种子质量分别是0.02kg，杂交得到的F1代的种子都是0.03kg，自交得1000个植株，4株0.018kg的种子，4株是0.04kg，其他植株的种子质量在这两个极端值之间，那么决定种子质量的基因有( )对。

单选题European farm ministers have ended three weeks of negotiations with a deal which they claim represents genuine reform of the common agricultural policy (CAP). Will it be enough to kick off the Doha world trade negotiations? On the face of it, the deal agreed in the early hours of Thursday June 26th looks promising. Most subsidies linked to specific farm products are, at last, to be broken--the idea is to replace these with a direct payment to farmers, .unconnected to particular products. Support prices for several key products, including milk and butter, are to be cut-that should mean European prices eventually falling towards the world market level. Cut-ting the link between subsidy and production was the main objective of proposals put forward by Mr. Fischler, which had formed the starting point for the negotiations. The CAP is hugely unpopular around the world. It subsidizes European farmers to such an extent that they can undercut farmers from poor countries, who also face trade barriers that largely exclude them from the potentially lucrative European market. Farm trade is also a key feature of the Doha round of trade talks, launched under the auspices of the World Trade Organization (WTO) in November 2001. Developing countries have lined up alongside a number of industrial countries to demand an end to the massive subsidies Europe pays its farmers. Several Doha deadlines have already been missed because of the EU's intransigence, and the survival of the talks will be at risk if no progress is made by September, when the world's trade ministers meet in Cancun, Mexico. But now even the French seem to have gone along with the deal hammered out in Luxembourg. Up to a point, anyway. The package of measures gives the green light for the most eager reformers to move fast to implement the changes within their own countries. But there is an escape clause of sorts for the French and other reform-averse nations. They can delay implementation for up to two years. There is also a suggestion that the reforms might not apply where there is a chance that they would lead to a reduction in land under cultivation. These 1et-outs are potentially damaging for Europe's negotiators in the Doha round. They could significantly reduce the cost savings that the reforms might otherwise generate and, in turn, keep European expenditure on farm support unacceptably high by world standards. Mote generally, the escape clauses could undermine the reforms by encouraging the suspicion that the new package will not deliver the changes that its supporters claim Close analysis of what is inevitably a very complicated package might confirm the sceptics' fears.

单选题对于突变与进化的关系，以下哪种说法最正确?( )

单选题Sanger的双脱氧末端终止法DNA序列测定中不需要下列哪种物质?______

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"I was just like you--I' thought I was invincible," says Adam Blomberg, standing before 400 students in a darkened auditorium at Miami's Coral Reef Senior High School. A photo of a bloodied and unconscious teenager, a breathing tube protruding from his mouth, flashes on the wall. "That was me," he says. There's a collective gasp before the room grows silent and Blomberg,31, an anesthesiologist who trained at Brigham and Women's Hospital in Boston, begins the story of what happened one night in February 1995. He created a presentation illustrating the dangers of behaving irresponsibly in a car, from not buckling up to speeding to driving under the influence of alcohol and drugs. He tracked down photos of teen crash victims from the center's archives, then incorporated statistics and his own experience. He spoke the first time to a local Boy Scout troop and was soon giving his talk, "A Survivor's Story," at high schools around the state. The Blomberg family had reason to celebrate. Adam had fully recovered and was on his way to fulfilling his lifelong dream of becoming a doctor. But in January 2000, Blomberg's 22-year-old step-brother, Michael, was killed in a crash while driving to his Atlanta home late one night. He wasn't wearing a seat belt. After the accident, Blomberg stopped telling his story to crowds, racked with guilt over his inability to reach Michael. If Blomberg had failed his own brother, he reasoned, how could he possibly make a difference to a roomful of strangers? Requests from schools continued to roll in, but he turned down every one. Then Blomberg got a call from a high school counselor. As he started into his standard excuse-lack of time—he looked across the room at a stack of thank-you notes from students who had heard him speak. He realized that kids needed to hear what he had to say. He agreed to visit the school and began contacting others on the waiting list for his talks. Blomberg leaves the school hoping he has changed someone's behavior. He recalls a letter he received from a student who heard him speak and got into a crash later that same day but was unharmed. " She told me she was wearing her seat belt because of me." Letters like this reinforce his belief that he survived the accident for a reason. "There are a lot of physicians in the world, and we all save lives," he says. "I have a special opportunity to save lives not just as a doctor but also as a human being./

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。

单选题下列性别畸形个体的体内相对不含雄性激素的是( )。

单选题以下哪种情况不属于同源重组?( )

单选题某些转座过程中( )是作为一种中间体存在的。

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