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Who won the World Cup 1994 football game? What happened at the United Nations? How did the critics like the new play? (1) an event takes place, newspapers are on the streets (2) the details. Wherever anything happens in the world, reporters are on the spot to (3) the news. Newspapers have one basic (4) , to get the news as quickly as possible from its source, from those who make it to those who want to (5) it. Radio, telegraph, television, and (6) inventions brought competition for newspaper. So did the development of magazines and other means of communication. (7) , this competition merely spurred the newspapers on. They quickly made use of the newer and faster means of communication to improve the (8) and thus the efficiency of their own operations. Today more newspapers are (9) and read than ever before. Competition also led newspapers to branch out into many other fields. Besides keeping readers (10) of the latest news, today's newspapers (11) and influence readers about politics and other important and serious matters. Newspapers influence readers' economic choices (12) advertising. Most newspapers depend on advertising for very (13) . Newspapers are sold at a price that (14) even a small fraction of the cost of production. The main (15) of income for most newspapers is commercial advertising. The (16) in selling advertising depends on a newspaper's value to advertisers. This (17) in terms of circulation. How many people read the newspaper? Circulation depends (18) on the work of the circulation department and on the services or entertainment (19) in a newspaper's pages. But for the most part, circulation depends on a newspaper's value to readers as a source of information (20) the community, city, county, state, nation, and world—and even outer space.

单选题 在碱基置换中，嘌呤碱基与嘧啶碱基的置换现象，称为（ ）。 A、转换　　B、颠换　　C、移码突变　　D、插入

单选题DNA聚合酶Ⅲ的描述中哪项不正确?( )

单选题玉米n+1的花粉不育，n+1的胚囊可育，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:1无 B．3红:1无 C．5红:1无 D．6红:1无

单选题Holliday中间体在( )过程中产生。

单选题Watson和Crick在1953年提出( )。

单选题在噬菌体的蛋白质外壳中含有______。

单选题DNA双螺旋结构模型的描述中哪一条不正确?______

单选题 人类的秃顶属于（ ）。 A、从性性状　　B、伴性遗传　　C、限性性状　　D、半合基因

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______。

单选题在做E.coli的转化实验时，要使E.coli处于感受状态，常用一种无机化合物处理，它是______。

单选题原核细胞遗传物质集中在细胞的一个或几个区域中，密度较低，与周围的细胞质无明确的界限，称作______。

单选题DNA解链(熔解)温度Tm决定于 a．A-T碱基对的比例； b．G-C碱基对的比例； c．A-T碱基对的比例和DNA变性条件； d．G-C碱基对的比例和DNA变性条件。

单选题侵染甲细菌后的噬菌体再去侵染另一种乙细菌，结果发生了甲乙细菌的基因重组，这是______。 A．转化 B．接合 C．转导 D．性导

单选题对于一个隔离的且数量已经大为减少的种群来说，其潜在的危险是( )。

单选题正反交结果一致的遗传方式有( )。

单选题基因的起始密码通常为AUG，但在少数情况下也可为GUG或UUG。这种少数情况 a．仅出现于真核细胞； b．仅出现于细菌； c．在真核和细菌中均有发生。

单选题在一个遗传平衡群体中，如果某一遗传病(XR——性连锁隐性遗传病)的男性发病率为0.04，该群体中女性的发病概率为( )。