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
27
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
Languageistheroadmapofaculture.Ittellsyouwhereitspeoplecomefromandwheretheyaregoing.AstudyoftheEnglish
Amajoringredienttotakingthepainoutofastressfuldayatworkisasupportivepartnerathome,anewstudyhas【B1】_____.
Americannewspapersarereportingwhatsomepeoplefearistheslowdeathoftheirownindustry.Newspapersearnmostoftheirm
A、Theyareveryexpensive.B、Theyareofhighquality.C、Theylookelegant.D、Theyarepretty.D生活交际类,事实细节题。女士认为商店橱窗里的展品非常漂亮。男士也
A、Inastudentcenter.B、Inaprofessor’soffice.C、Inarestaurant.D、Inadoctor’soffice.B校园生活类,场景推断题。女士需要男士在计划书导师签名处签名,男士表示
A、Climatechange.B、Foodsecurity.C、Populationgrowth.D、Droughtproblem.B事实细节题。本题问的是20国会议的主要焦点是什么。短文中间提到,世界上最大的经济峰会20国会议将“食品安
A、Theinformationistoomuchandisdisplayedmessily.B、Theinformationappearstobelongandboring.C、Theinformationisto
A、Themoviescan’tberemadeanymore.B、ThemovieswillbeuploadedtotheInternet.C、Themoviescan’tcompeteinfilmfestiva
A、Healthconditionsimprovewithtimespentwatchinghealthyprograms.B、Comedyvideoscancuremostpeopleofchronicheartatt
A、Studyinaquietplace.B、Improvehergradesgradually.C、Changetheconditionsofherdorm.D、Avoiddistractionswhilestudyi
随机试题
人民警察询问治安案件的被侵害人或者其他证人,正确的说法是()。
格林-巴利综合征不常有的表现是
以下哪些是M胆碱受体兴奋的表现
根据《仲裁法》,仲裁庭作出的裁决书生效后,在下列哪一情形下仲裁庭不可进行补正?(2011年卷三50题)
试述董事、高级管理人员的禁止行为。
下列关于时间序列的速度分析,表述正确的有()。
北京市黎明会计师事务所承接了乙上市股份有限公司2006年度的会计报表审计业务。事务所所长黎明任主任会计师,负责审计工作底稿的最终复核工作,王豪任项目经理、注册会计师李民及其他注册会计师和助理人员负责具体的审计工作。本次审计确定乙公司2006年度会计报表层
让被测者站直,双手自然下垂,测量髂前上棘和背后臀大肌最凸处即可得到臀围。
图4显示了新中国成立后农业集体化的进程,其中的X应是()。
SQL语句中修改表结构的命令是( )。
最新回复
(
0
)