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
2017-02-01
53
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/rlF7777K
0
大学英语六级
相关试题推荐
A、Rockmusic.B、Classicmusic.C、Americancountrymusic.D、Lightmusic.C事实细节题。本题问的是电台正在放什么音乐。女士说这是小提琴音乐。它是一种纯正的美国音乐,来自大山的乡村音乐。
Amajoringredienttotakingthepainoutofastressfuldayatworkisasupportivepartnerathome,anewstudyhas【B1】_____.
Amajoringredienttotakingthepainoutofastressfuldayatworkisasupportivepartnerathome,anewstudyhas【B1】_____.
Onewouldthinkthatbynowmostpeoplewouldhave【B1】______thatclimatechangerepresentsagravethreattotheplanet.Onewou
A、Itisgreatbutnotverylarge.B、ItisthelargestshoppingcenterinAmerica.C、Itprovidescomprehensiveservicesforcusto
A、Likeamanualworker.B、Likeanelegantprincess.C、Likearichwoman.D、Likeasuccessfulofficelady.C生活交际类,语义理解题。男士说派对女主人浑
Dohalfofallmarriagesreallyendindivorce?It’sprobablythemostoften【B1】_____statisticaboutmodernlove.Butinanupbe
Dohalfofallmarriagesreallyendindivorce?It’sprobablythemostoften【B1】_____statisticaboutmodernlove.Butinanupbe
A、Healthconditionsimprovewithtimespentwatchinghealthyprograms.B、Comedyvideoscancuremostpeopleofchronicheartatt
OxfordUniversityoncefamouslyclaimedtohavebeenfoundedbyAlfredtheGreatinthe9thCentury.Butinfact,theUniversity
随机试题
企业以人为本,形成一流的员工队伍,为市场创造适销对路的产品,提供最佳的服务,以展现员工良好的职业道德、较高的文化素养,崇高的精神风貌所进行的长远性谋划与方略是()
下列对计算机软件认识不正确的是______。
A.急性闭角型青光眼B.弱视C.缺血性视神经病变D.开角型青光眼E.以上均不是逐渐视力下降无眼痛
格林-巴利综合征脑脊液的特点是
移动平均法应用于消极型股票投资战略。( )
公司债券只能是记名债券。()
驾驶员在正常行车途中,发现两个小孩从侧面横过马路,驾驶员刹不住车,急转方向盘,汽车朝路旁的空房撞去,致车和空房损坏严重。驾驶员的行为是()。
政策性投资也叫竞争性投资。()
下列说法中,正确的是
Wheremostlikelyarethespeakers?
最新回复
(
0
)