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
考研
Genetic engineering holds great potential payoffs for farmers and consumers by making crops resistant to pests, diseases, and ev
Genetic engineering holds great potential payoffs for farmers and consumers by making crops resistant to pests, diseases, and ev
admin
2009-05-21
145
问题
Genetic engineering holds great potential payoffs for farmers and consumers by making crops resistant to pests, diseases, and even chemicals used to kill surrounding weeds; but new research raises concerns that altering crops to withstand such threats may pose new risks--from none other than the weeds themselves. This is due to the weeds’ ability to acquire genes from the neighboring agricultural crops. Researchers found that when a weed cross-breeds with a farm-cultivated relative and thus acquires new genetic traits--possibly including artificial genes engineered to make the crop hardier--the hybrid weed can pass along those traits to future generations.
"The result may be very hardy, hard-to-kill weeds," said Allison Snow, a plant ecologist at Ohio State University in Columbus who conducted the experiments over the past six years along with two colleagues. They presented their results last week at the annual meeting of the Ecological Society of America in Madison, Wisconsin.
The findings suggest that genetic engineering done with the aim of improving crops--growing the new genetic traits such as resistance to herbicides or pests-- could ultimately have unintended and harmful consequences for the crops if weeds acquire the same trait and use it to out-compete the crops. "Gene movement from crops to their wild relatives is an ongoing process that can be ultimately harmful to crops," said Snow.
The results of the experiments challenge a common belief that hybrids gradually die out over several generations, Snow explained. "There has been an assumption that crop genes wouldn’t persist in crop-weed hybrids" because hybrids are thought to be less successful at reproducing, she said. However, Snow’s research contradicted this assumption: Hybrid wild radishes survived in all six generations that were grown since the study began.
Although the genetic traits the scientists monitored were natural and not genetically engineered, the findings nonetheless suggest that artificial improvements introduced into crops through genetic engineering could spread to weeds and become permanent traits of the weed population.
So strengthened, the weeds may pose a serious risk to the long-term health of agricultural crops. The danger exists in a number of crop plants--including rice, sunflower, sorghum, squash, and carrots--that are closely related to weeds with which they compete. Snow is concerned that the transfer of genes from crops to related weeds could rapidly render many herbicides (chemicals which kill weeds) ineffectual. That situation, she said, would be much like bacterial diseases acquiring resistance to antibiotics.
Because plant hybrids arise in a single generation, however, it could happen much more quickly; "Modern agriculture is heavily dependent on herbicides," she said, "so people will notice when those don’t work anymore."
选项
A、threats posed by chemicals used to kill weeds
B、risks of altering crops’ genetic make up’s
C、dangers inherent in the nature of weeds
D、the results of recent research
答案
B
解析
这是一道词义题。题干中的信号词出自于文章第一段第二句话中。文章第一段指出:新的研究引发了人们的这些忧虑,改变农作物,以便它们抵御这样的灾害可能导致新的危险——不是别的,正是杂草本身;这是因为,杂草能够从邻近的农作物那里获得基因。这说明,该单词应该是指改变农作物成分的风险。B说“改变农作物的基因成分的风险”,这与文章的意思相符。与A和C有关的信息是第一段的第一句话,但并不是该词所指的内容;与D有关的信息是第一段的最后一句话,文中是说“研究人员发现,当一种杂草与农场栽培的农作物类植物杂交时它就因此获得新的基因特征”,这也不是该词所指的内容。
转载请注明原文地址:https://kaotiyun.com/show/Xxe4777K
0
考研英语二
相关试题推荐
Themainideaofthefirstparagraphisthat______.Itisimpliedinthepassagethat______.
Geneticengineeringholdsgreatpotentialpayoffsforfarmersandconsumersbymakingcropsresistanttopests,diseases,andev
Animportantfactorofleadershipisattraction.Thisdoesnotmeanattractivenessintheordinarysense,forthatisabornqua
Animportantfactorofleadershipisattraction.Thisdoesnotmeanattractivenessintheordinarysense,forthatisabornqua
Animportantfactorofleadershipisattraction.Thisdoesnotmeanattractivenessintheordinarysense,forthatisabornqua
Thebesttitleforthispassagewouldbe______.Howdoestheauthorrespondtotheprevailingattitudetowarddefenseattorney
Youstillneedsomesubstantialexamples______supportofyourargument,orfewpeoplewillbelieveinyouridea.
Thecellphone,adevicewehavelivedwithformorethanadecade,offersagoodexampleofapopulartechnology’sunforeseensi
Readthefollowingtextandanswerquestionsbyfindinginformationfromtherightcolumnthatcorrespondstoeachofthemarked
随机试题
Word2003程序启动后就自动打开一个名为“文档1”的文档,保存时系统默认的文件夹是_________。
蟾酥能解毒消肿,止痛开窍,因其有毒,内服务必掌握用量,临床一日常用量为
采集血清酶及肝功能测定应使用的血标本类型是
只能采用现金轧差方式结算的金融期权是()。
2017年1月1日,甲公司用银行存款3300万元从证券市场上购入乙公司发行在外的80%股份并能够控制乙公司。同日,乙公司所有者权益账面价值为3800万元(其中:股本为3000万元,盈余公积为80万元,未分配利润为720万元),可辨认净资产公允价值为4000
(2013年)已达到预定可使用状态但尚未办理竣工决算的固定资产不应计提折旧。()
社会工作者在调研中发现,社区中不少外来媳妇互不相识,很少交往,其中部分女性还被丈夫虐待。小海协助这些妇女成立小组,下列小组类型中最合适的是()。
体检:化验:健康
下列哪些概念判断适用于有限责任公司?()
IntheUnitedStates,itisnotcustomarytotelephonesomeoneveryearlyinthemorning.Ifyoutelephonehimearlyintheday,
最新回复
(
0
)