首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
If you go down to the woods today, you may meet high-tech trees—genetically modified to speed their growth or improve the qualit
If you go down to the woods today, you may meet high-tech trees—genetically modified to speed their growth or improve the qualit
admin
2018-08-25
26
问题
If you go down to the woods today, you may meet high-tech trees—genetically modified to speed their growth or improve the quality of their wood. Genetically-engineered food crops have become increasingly common, albeit controversial, over the past ten years. But genetic engineering of trees has lagged behind.
Part of the reason is technical. Understanding, and then altering, the genes of a big pine tree are more complex than creating a better tomato. While tomatoes sprout happily, and rapidly, in the laboratory, growing a whole tree from a single, genetically altered cell in a test tube is a tricky process that takes years, not months. Moreover, little is known about tree genes. Some trees, such as pine trees, have a lot of DNA—roughly ten times as much as human. And, whereas the Human Genome Project is more than half-way through its task of isolating and sequencing the estimated 100, 000 genes in human cells, similar efforts to analyze tree genes are still just saplings(幼苗).
Given the large number of tree genes and the little that is known about them, tree engineers are starting with a search for genetic "markers". The first step is to isolate DNA from trees with desirable properties such as insect resistance. The next step is to find stretches of DNA that show the presence of a particular gene. Then, when you mate two trees with different desirable properties, it is simple to check which offspring contain them all by looking for the genetic markers. Henry Amerson, at North Carolina State University, is using genetic markers to breed fungal resistance into southern pines. Billions of these are grown across America for pulp and paper, and outbreaks of disease are expensive. But not all individual trees are susceptible. Dr. Amerson’s group has found markers that distinguish fungus-resistant stock from disease-prone trees. Using traditional breeding techniques, they are introducing the resistance genes into pines on test sites in America.
Using genetic markers speeds up old-fashioned breeding methods because you no longer have to wait for the tree to grow up to see if it has the desired traits. But it is more a sophisticated form of selective breeding. Now, however, interest in genetic tinkering(基因修补)is also gaining ground. To this end, Dr. Amerson and his colleagues are taking part in the Pine Gene Discovery Project, an initiative to identify and sequence the 50,000-odd genes in the pine tree’s genome Knowing which gene does what should make it easier to know what to alter.
What is the primary objective of carrying out the Pine Gene Discovery Project?
选项
A、To speed up old-fashioned breeding methods.
B、To identify all the genes in the pine tree’s genome.
C、To find out what desired traits the pine trees have.
D、To make it easier to know which gene needs altering.
答案
B
解析
末段倒数第2句中的an initiative是the Pine Gene Discovery Project的同位语,表明开展该计划的目的,因此选项B为本题答案。其他选项都是在完成该计划后能够达成的工作,它们都要以松树基因的排列组合为基础,因此,这些选项都不是primary objective,而是在实现了primary objective之后继续进行的工作。
转载请注明原文地址:https://kaotiyun.com/show/RHH7777K
0
大学英语六级
相关试题推荐
Millionsofschool-leaversintherichworldareabouttobidatearfulgoodbyetotheirparentsandstartanewlifeatunivers
Theselfishnessofhumansisacentralassumptionoforthodox(传统的)economics,whereitisthoughttoleadtobenefitsfortheeco
Gulliverhasafriendwhorecentlygaveuphisjobtostudyfor"TheKnowledge",thenotoriouslydifficultprogrammethatLondo
GetEnoughSleep—orElse!Agoodnight’ssleepismoreimportanttoyourhealththanyoumayrealize.[A]MeganJoneskne
TheHealthBenefitsofDrinkingWater—Isbottleddrinkingwaterhealthierthanfilteredtapwater?[A]Waterisakeyin
Parentscaneasilycomedownwithanacutecaseofschizophrenia(精神分裂症)fromreadingthecontradictoryreportsaboutthestateof
NowomancanbetoorichortoothinThissayingoftenattributedtothelateDuchess(公爵夫人)ofWindsorembodiesmuchoftheodds
Itisnogooddwellingonthepast.Whatexistedorhappenedinthepastmayhavebeenbeautifulorexcitingandmaynowbringp
Googlemustbethemostambitiouscompanyintheworld.Itsstatedgoal,"toorganizetheworld’sinformationandmakeitunive
Somefuturologistshaveassumedthatthevastupsurge(剧增)ofwomenintheworkforcemayportendarejectionofmarriage.Manyw
随机试题
Itisnotpolitetoarriveatadinnerpartymorethan15to20minuteslate.Thehostorhostessusuallywaitsforallthegues
A.HBsAgB..HBcAgC.HBeAgD.抗-HBsE.抗-HBc存在于Dane颗粒表面()
男性,28岁。突起畏寒发热,右胸痛2天,X线胸片示右下肺叶大片模糊影。可能诊断
本病诊断为何病本病治法为
已知向量组α1,α2,α3线性无关,α1+2α2,α1+3α3,2α2+tα3线性相关,则t=()。
投资者教育具体应重点突出的内容有()。
某企业与海外公司2008年签订一份金额为500万美元的采购合同,并按规定缴纳了印花税,2009年修改该合同,将金额增加为721万美元,修改凭证当日的美元与人民币的汇率为6.28,当月1日美元与人民币的汇率为6.38,则该企业2009年应缴纳的印花税为人民币
由于交通部门的原因,原定班次或车次变更而导致漏接发生,旅游者对导游员抱怨、发火,导游员应()。
WhatwasMary’sjob?WhatcouldMary’scatsay?Shecouldsay______.
ACareerinAccounting Asafieldofstudyandwork,accountingisexpandingthroughouttheworld.Ajobinaccounting
最新回复
(
0
)