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
2016-04-30
33
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/XtG7777K
0
大学英语六级
相关试题推荐
Television:theCyclopsthatEatsBooksA)WhatisdestroyingAmericatodayisnottheliberalbreedofpoliticians,ortheInter
Television:theCyclopsthatEatsBooksA)WhatisdestroyingAmericatodayisnottheliberalbreedofpoliticians,ortheInter
YouDon’tHavetoBe18:GoingtoCollegeasanAdultA)Everysooften,especiallywhenI’mfeelingdown,Itakeoutmyoldcoll
TheAmericaneconomicsystemisorganizedaroundabasicallyprivateenterprise.It’s【B1】______economyinwhichconsumersdeterm
TheAmericaneconomicsystemisorganizedaroundabasicallyprivateenterprise.It’s【B1】______economyinwhichconsumersdeterm
Awisemanoncesaidthattheonlythingnecessaryforthetriumphofevilisforgoodmentodonothing.So,asapoliceoffice
A、Nomedicinecouldsolvethewoman’sproblem.B、Thewomanshouldeatlesstolosesomeweight.C、Nothingcouldhelpthewomani
Settinganearlierbedtimeforyourchildrencouldhelpkeeptheirweight【B1】______,anewstudyfinds.Fastfood,toomuchscree
Settinganearlierbedtimeforyourchildrencouldhelpkeeptheirweight【B1】______,anewstudyfinds.Fastfood,toomuchscree
IfthepopulationoftheEarthgoesonincreasingatitspresentrate,therewilleventuallynotbeenoughresourcesleftto【B1】
随机试题
下列选项中,不是我国央行用狭义货币供应量表示符号的为()。
甲向乙购买一批货物,合同约定丙为鉴定人,丁为担保人,关于该合同印花税纳税人的下列表述中,正确的是()。(2012年)
导致湿地破坏的主要原因是()。
关于垃圾分类处理,下列说法错误的是()。
非指导性教学属于()
舌神经阻滞麻醉可麻醉的部位是()。
设四元齐次线性方程组求:(1)与(2)的公共解。
Inrecentdays,AmericanAirlineshasbeenforcedtocancelmorethan40flightsinPhoenix.Thereason:Withdaytimehighshove
书写查询条件时,日期值应该用()括起来。
ItispossibleforsomestudentsinHigherEducationinBritaintoborrowmoneythroughagovernmentscheme.Theseloansarecal
最新回复
(
0
)