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
21
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://jikaoti.com/ti/fSSFFFFM
0
大学英语六级
相关试题推荐
Electronictrash,knownase-waste,ispilingupfasterthaneverinAmericanhomesandbusinesses.Peopledonotknowwhattod
Electronictrash,knownase-waste,ispilingupfasterthaneverinAmericanhomesandbusinesses.Peopledonotknowwhattod
Theselfishnessofhumansisacentralassumptionoforthodox(传统的)economics,whereitisthoughttoleadtobenefitsfortheeco
A、Anarticleaboutthelatestnews.B、Aresumeandsomephotographworks.C、Anessayforaliteratureclass.D、Aself-introducti
RisingInequalityIsHoldingBacktheU.S.Economy[A]Inannouncinghisrunforthepresidencylastmonth,JebBushhassetan
It’sagoodideatoapplysunscreenbeforeheadingtothebeachifyoudon’twanttoburn.Butformarineanimalslikewhales,t
SecretE-Scores[A]Americansareobsessedwiththeirscores.Creditscores,G.P.A.’s,SAT’s,bloodpressureandcholesterol(
Aristotledefinedafriendas"asinglesouldwellingintwobodies".MembersofFacebookwhose"friends"reachtriplefiguresm
Googlemustbethemostambitiouscompanyintheworld.Itsstatedgoal,"toorganizetheworld’sinformationandmakeitunive
TheHistoryofChineseAmericans[A]ChinesehavebeenintheUnitedStatesforalmosttwohundredyears.Infact,theChines
随机试题
设有两个关系模式:职工(职工号,姓名,性别,年龄,职务,工资,部门号)部门(部门号,部门名称,经理名,地址,电话)依据上述关系回答下面小题。试用SQL语句定义一个包含姓名、性别、工资、职务和部门名称的视图ZBB。
接受捐赠的固定资产,按末来应交的所得税,贷记“应交税费——应交所得税”。()
会计工作交接完毕后,下列哪类人员可以不用必须在移交清单上签名或盖章()。
温州江心屿是中国四大名屿之一,屿中名胜古迹众多,最为有名的是()。
设定KPI指标和指标值时,一般不会选取()作为参考标杆。
搜查时,必须有被搜查人或者他的家属、邻居或者其他见证人在场。( )
简答语法规则的抽象性表现。
考生文件夹下存在一个数据库文件“samp3.accdb”,里面已经设计了表对象“tEmp”、窗体对象“fEmp”、报表对象“rEmp”和宏对象“mEmp”。试在此基础上按照以下要求补充设计:将窗体按钮“btnP”的单击事件属性设置为宏“mEmp”,以完
某模拟网站的主页地址是HTIP://LOCALHOST:65531/ExamWeb/INDEX.HTM,打开此主页,浏览“航空知识”页面,查找“运十运输机”的页面内容,并将它以文本文件的格式保存到考生目录下,命名为“yloysj.txt”。
ThemostfamouspainterinVictoria’shistoryisEmilyCarr.Whenshewasachild,shediscoveredthatwalkinginthewoods【C1】_
最新回复
(
0
)