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
2019-06-23
40
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 does the author think about the genetic engineering of pine trees?
选项
A、Time-consuming.
B、Worthwhile.
C、Significant.
D、Technically impossible.
答案
A
解析
第2段第3句中的that takes years表明研究树木的基因改造技术将花费很长时间,因此选项A为本题答案。原文没有就选项B和C两方面做出讨论,因此不能推断出这两个选项;虽然第2段首句提到technical一词,但文章表明树木基因改造技术是可行的,只是会花费较多的时间,因此选项D也不正确。
转载请注明原文地址:https://kaotiyun.com/show/ayX7777K
0
大学英语六级
相关试题推荐
A、Humansgothelpfromotherspecies.B、Humanssurvivebyexploration.C、Humanssurvivebyingenuity.D、Humanssurvivebyluck.
A、Hestilllivedinhiscollegedormroom.B、Hemadealivingbysellingwinebottles.C、Hegotmoneyfromoneofhisfriends.D
A、English.B、AlgebraC、History.D、Spanish.B
A、Peoplearenotfullypreparedforpotentialrisks.B、Peoplearenothealthyenoughforoutdooractivities.C、Peoplearetooea
Theextentandlimitsofape(猿)intelligenceisahotareainscience,butmostoftheresearchhasfocusedoncognition.Nowa
Theextentandlimitsofape(猿)intelligenceisahotareainscience,butmostoftheresearchhasfocusedoncognition.Nowa
TricksoftheTrade[A]Aschildren,wearetaughtthatworkinghardwillgetusgoodgrades.Whenitcomestoyourjob,thesam
Cryingishardlyanactivityencouragedbysociety.Tears,betheyofsorrow,anger,orjoy,typicallymakeAmericansfeeluncom
Cryingishardlyanactivityencouragedbysociety.Tears,betheyofsorrow,anger,orjoy,typicallymakeAmericansfeeluncom
A、Studentscanlearnaboutdifferentkindsofjobs.B、Theycanlearnskillsandgainvaluableexperience.C、Theycanmeetimport
随机试题
A、三尖瓣区B、肺动脉瓣区C、二尖瓣区D、主动脉瓣第二听诊区E、主动脉瓣区胸骨右缘第2肋间隙是
下列关于化学性突触的说法错误的是
患者,男性,患有胃溃疡,昨日呕血约400ml,经治疗出血停止,病情缓解,大便隐血试验阴性。患者呕血后应采取的体位是
初步可行性研究的主要目的是判断项目是否有生命力,是否值得投入更多的()进行可行性研究,并据此做出是否进行投资的初步决定。
建设工程项目进度控制是一个()的控制过程。
动产质押合同( )。
当企业出现现金短缺,是由出纳保管不善造成的,则应记入()账户。
关于报告测验分数的具体建议中,下列说法正确的是()。
在IPSec协议族中,有两个主要的协议,分别是______协议和身份认证头协议。
Therateatwhichmanhasbeenstoringupusefulknowledgeabouthimselfandtheuniversehasbeenspiralingupwardfor10,000y
最新回复
(
0
)