单选题已知有三个位点是连锁的，D和E相距20个图距单位，E和F相距20个图距单位，又知三位点的顺序是DEF。用杂交DDEEFF×ddeeff的子代进行测交，就表型分类，发现测交子代中，有2%的DdeeFf和2%的ddEeff，根据这些资料，此区段的并发系数______ A.1 B.0.5 C.0 D.已给的资料可计算并发系数，但上述答案都不对 E.不能计算并发系数

单选题肾上腺激素是通过______起作用的。

单选题关于脂肪酸β-氧化的叙述，错误的是

单选题A．α-螺旋B．左手双螺旋C．右手双螺旋D．三叶草E．倒L型

单选题不属于高能磷酸化合物的是

单选题临床上出现黄疸时，尿中可检出的化合物是 A.胆红素 B.尿胆素原 C.尿胆素 D.尿胆红素 E.粪胆素

单选题催化聚合酶链式反应的酶是______ A.DNA连接酶 B.反转录酶 C.末端转移酶 D.DNA聚合酶I E.TaqDNA聚合酶

单选题In old days, when a glimpse of stocking was looked upon as something far too shocking to distract the serious work of an office, secretaries were men. Then came the first World War and the male secretaries were replaced by women. A man's secretary became his personal servant, charged with remembering his wife's birthday and buying her presents; taking his suits to the dry cleaners; telling lies on the telephone to keep people he did not wish to speak to at bay and, of course, typing and filing and taking shorthand. Now all this may be changing again. The microchip and high technology is sweeping the British office, taking with it much of the routine clerical work that secretaries did. "Once office technology takes over generally, the status of the job will rise again because it will involve only the high-powered work-and then men will want to do it again." That was said by one of the executives(male) of one of the biggest secretarial agencies in this country. What he has predicted is already under way in the US. One girl described to me a recent temporary job placing men in secretarial jobs in San Francisco. She noted that all the men she dealt with appeared to be gay so possibly that is just a new twist to the old story. Over here, though, there are men coming onto the job market as secretaries. Classically, girls have learned shorthand and typing and gone into a company to seek their fortune from the bottom——and that's what happened to John Bowman. Although he joined a national grocery chain as secretary to its first woman senior manager, he has since been promoted to an administration job. "I filled in the application form and said I could do audio/typing, and in fact I was the only applicant. The girls were reluctant to work for this young, glamorous new woman with all this power in the firm. " "I did typing at school, and then a commercial course. I just thought it would be useful finding a job. I never got any funny treatment from the girls, though I admit I've never met another male secretary. But then I joined the Post Office as a clerk and carelessly played with the typewriter, and wrote letters, and thought that after all secretaries were getting a good ￡1,000 a year more than clerks like me. There was a shortage at that time, you see. " "It was simpler working for a woman than for a man. I found she made decisions, she told everybody what she thought, and there was none of that stuff' ring this number for me dear, which men go in for." "Don't forget, we were a team—that's how I about it—not boss and servant but two people doing different things for the same purpose." Once high technology has made the job of secretary less routine, will there be male takeover? Men should beware of thinking that they can walk right into the better jobs. There are a lot of women secretaries who will do the job as well as they because they are as efficient and well trained to cope with word processors and computers, and men.

单选题关于转氨基作用的叙述，错误的是

单选题痛风症时，沉积于关节、肾等处的成分是

单选题有一糖蛋白经测定其含氮量为0.5mol，那么其蛋白质含量为多少?______

单选题有机磷农药中毒主要是它们能特异地和酶活性中心哪种基团结合

单选题白喉毒素抑制的过程是 A.翻译起始过程 B.翻译延长过程 C.翻译终止过程 D.DNA拓扑异构酶反应 E.核酶反应

单选题下列哪项属组成性基因表达

单选题有关mRNA的叙述正确的是______ A.hnRNA中只含有基因编码区转录的序列 B.在3'端具有SD序列 C.mRNA的遗传密码方向是5'→3' D.在细胞内总RNA含量中所占比例很大 E.mRNA碱基序列与DNA双链中的反义链一致

单选题In the two decades between 1910 and 1930, over ten percent of the Black population of the United States left the South, where the majority of the Black population had been located, and migrated to northern states, with the largest number moving, it is claimed, between 1016 and 1918. It has been frequently assumed, but not proved, that most of the migrants in what has come to be called the Great Migration came from rural areas and were motivated by two concurrent factors: the collapse of cotton industry following boll weevil infestation, which began in 1898, and increased demand in the North for labor following the cessation of European immigration caused by the outbreak of the First World War in 1914. This assumption has led to the conclusion that the migrants' subsequent lack of economic mobility in the North is tied to rural background, a background that implies unfamiliarity with urban living and a lack of industrial skills. But the question of who actually left the South has never been investigated in detail. Although numerous investigations document a flight from rural southern areas to southern cities prior to the Great Migration, no one has considered whether the same migrants then moved on to northern cities. In 1910 over 600,000 Black workers, or ten percent of the Black work force reported themselves to be engaged in "manufacturing and mechanical pursuits", the federal census category roughly including the entire industrial sector. The Great Migration could easily have been made up entirely of this group and their families. It is perhaps surprising to argue that an employed population could be tempted to move, but an explanation lies in the labor conditions then prevalent in the South. About thirty-five percent of the urban Black population in the South was engaged in skilled trades. Some were from the old artisan class of slavery--blacksmiths, masons, carpenters--which had a monopoly of certain trades, but they were gradually being pushed out by competition, mechanization, and obsolescence. The remaining sixty-five percent, more recently urbanized, worked in newly developed industries--tobacco, lumber, coal and iron manufacture, and railroads. Wages in the South, however, were low, and Black workers were aware, through labor recruiters and the Black press, that they could earn more even as unskilled workers in the North than they could as artisans in the South. After the boll weevil infestation, urban Black workers faced competition from the continuing influx of both Black and White rural workers, who Were driven to undercut the wages formerly paid for industrial jobs. Thus, a move north would be seen as advantageous to a group that was already urbanized and steadily employed, and the easy conclusion tying their subsequent economic problems in the North to their rural backgrounds comes into question. Notes: boll weevil infestation 棉铃虫蔓延。cessation 中止，停止。mason 泥瓦匠。recruiter 招募者。influx流入，涌入。

单选题关于蛋白质腐败作用的叙述，错误的是

单选题在生理pH条件下，具有缓冲作用的氨基酸残基是( )。

单选题有关生物氧化描述错误的是 A.生物氧化是在体温下、pH7.35～7.45的生理条件下进行的 B.生物氧化是一系列酶促反应 C.生物氧化过程是逐步氧化、逐步释放能量的 D.生物氧化过程消耗氧，氧化的终产物是H2O、CO2和能量 E.生物氧化过程中产生的能量都以ATP的形式储存和利用

单选题含有输送肽序列的前体蛋白质通过跨膜受体TOC和TIC进入叶绿体的基质时需要消耗______。