单选题哈迪-温伯格定律表示群体在逐代中的遗传平衡，这一定律的数学表示为( )。

单选题细菌中，同源重组发生在一些热点周围，这和( )在chi位点上的单链内切酶活性有关。

单选题酵母DNA的A+T/G+C为2，则A/G、A/C、A/T应分另0为( )。

单选题Electronics are being recycled in record numbers as more states require it and more companies collect and even pay for discarded items, but the gains come with controversy. Some environmentalists complain that recycling is not keeping pace with electronics sales. Some say e-waste is being dumped in developing countries, where toxic materials such as lead and mercury can leach from landfills into groundwater. "It is a success story, but we'd like to see it get more successful" to keep up with the electronics boom, says Janette Petersen of the Environmental Protection Agency (EPA). The amount of recycled items more than doubled from 1999 to 2007, the most recent year for which the EPA has figures. But as a percentage of all electronics, it increased less, from 15% to 18%. "The demand for electronics recycling has been growing," partly because of the switch last year to digital TV, says Jennifer Berry of Earth911. corn, a private group that keeps a database of recyclers. Last year, she says 31% of inquiries involved electronics, primarily TVs, batteries and computers. Public and private efforts are expanding. Vermont became the 21st state last month to enact a law that requires e-waste recycling. Twenty-six companies--including Dell, Hewlett Packard, ATT and Verizon--have partnered with the EPA on the Plug-In to eCycling program to promote electronics recycling since its launch in 2003. Companies such as Gazelle. corn pay for used gadgets such as iPods, which they resell or recycle. Best Buy and other stores are collecting more e-waste. Target announced last month that it put bins in every store to accept cellphones, MP3 players and ink cartridges. Jim Puckett of Basel Action Network, a Seattle-based non-profit organization that aims to stop toxic exports, worries that some American companies dump e-waste in Africa to save money. "People are trying to look green, but they're not telling you where it (waste) is going," he says. "You can't turn over your TV to just any recycler. " He says it's better to store an old TV than give it to a recycler that may export it to poor countries. The Basel Action Network announced its e-Stewards program last month to ensure safe handling of electronics by using only recyclers certified by accredited organizations. It now lists 45 recyclers in 80 locations. Samsung and other companies have signed on. Environmental groups, including the Sierra Club, back it.

单选题核型为48，XXXX的女性，她的巴氏小体有______。 A.一个 B.二个 C.三个 D.四个

单选题用中性小菌落与分离型小菌落的酵母杂交，经减数分裂后所得子代分离比是 ____ 。

单选题为了确定T4噬菌体的h和r位点间的重组率，利用大量的h+r-和h-r+噬菌体对E.coli进行复感染，收集裂解液，分析其基因型，结果是：h+r+=2000；h+r-=3000；h-r+=3000；h-r-=2000，这些资料说明两位点间的重组率是______ A.40% B.75% C.57% D.60% E.上述答案均不对

单选题以下哪种情况不属于同源重组? ____

单选题______不能独立地复制DNA。

单选题用中性小菌落与分离型小菌落的酵母杂交，经减数分裂后所得子代分离比是______。

单选题设某一植物中的两个连锁位点之间交换值为21%，如果检查了这两位点间的交叉时记录了150个孢母细胞，则应该有______个孢母细胞会在这两位点间形成交叉。 A．21 B．42 C．63 D．84

单选题mRNA核苷酸顺序的3′→5′分别相应于蛋白质氨基酸顺序的 a．N端-C端； b．C端-N端； c．与N端、C端无对应关系。

单选题酵母DNA的A+T/G+C为2，则A/G、A/C、A/T应分别为______。

单选题原始的原核生物的新陈代谢类型最可能的是( )。

单选题真核细胞的染色质主要是由以下______成分构成的。

单选题在独立遗传下，杂种AaBbDdEe自交，后代中基因型全部纯合的个体占______。 A．25% B．1/8 C．1/16 D．9/64

单选题正反交结果一致的遗传方式有 ____ 。

单选题人工选择之所以能选育出新品种，自然选择之所以能形成新物种，其共同的选择基础是( )。

单选题某人是一个常染色体基因的杂合子Bb，而他带有一个隐性的X连锁基因d。在他的精子中有多大比例带有bd基因? (a)0； (b)1/2； (c)1/8； (d)1/16； (e)1/4。

单选题______可以促进非严格配对的两段DNA发生重组。