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
A few milliamps of electricity can cause plants to increase synthesis of chemicals. These compounds often also have a pharmacolo
A few milliamps of electricity can cause plants to increase synthesis of chemicals. These compounds often also have a pharmacolo
admin
2013-06-10
87
问题
A few milliamps of electricity can cause plants to increase synthesis of chemicals. These compounds often also have a pharmacological (related to medicine) or commercial value, so the trick could be used to help increase yields of commercially useful biologicals. Artemisinic acid, from sweet wormwood, for example, is used in malarial medications, and shikonin (紫草素), from the purple gromwell plant, is used against skin infections.
Researchers have long known that stressing plants can force them to take defensive action, often ramping up the production of protective chemicals that, for example, make them more resistant to insect attack. It has become common practice to stress such plants into increasing their yields. This is usually clone using physical stress elicitors (诱导子), including bits of the micro-organisms that normally attack the plants, or irritants made from metallic compounds such as copper chloride. These are effective, but they come at a cost. Most elicitors are toxic to plants and can build up in tissues, making it necessary to occasionally "clean" a plant of the chemicals so they keep having the same effect.
Recently, research groups at the University of Arizona in Tucson found that the application of an electric current to the hairy roots of the poisonous herb Hyoscyamus muticus stimulated the production of the herb’s toxin hyoscyamine (天仙子胺). This unpublished finding inspired Hans Van Etten, also of the University of Arizona, and his colleagues to test sub-lethal levels of electrical currents on other plants, to assess electricity’s potential to elevate chemical production.
The researchers exposed eight different plant species (ranging from Japanese pagoda tree seedlings to pea plants) to weak electrical currents of 30 milliamps. Seven of the plants increased their production o{ defensive chemicals. The average boost of chemical production was 20 times, they report in Biotechnology Progress. One plant, a type of alfalfa, increased its chemical yield by 168 times. These values are very similar to those achieved using chemical elicitors, and seem to have no lethal effects-just a negative effect on growth. The treatment can be used over and over again without the build-up of any unwanted material.
The useful compounds would be very easy to harvest: they simply pour out into solution if the plants are grown hydroponically. "The fact that we can use electricity instead of toxic materials to elicit chemical production is very exciting because it means we get to look at how these chemicals form without having to constantly add and remove toxins from the system," says Van Etten. "This is a really novel and creative approach that I’ve never seen before," says plant metabolic engineer Fabricio Medina Bolivar from Arkansas State University in Jonesboro. "The possibilities for using electricity with plants in this way are absolutely tremendous. "
What is the main idea of the passage?
选项
A、Reactions to the electric stress lead to more chemical yields.
B、Yields of commercially useful biologicals are increased.
C、Using electricity to elicit chemical production is very exciting.
D、Using electricity has a negative effect on plant growth.
答案
A
解析
主旨大意题需要把握全文框架结构。通览全文可知,通篇讲了一个问题,即开头所提到的“几毫安的电流就能够使植物增加化学合成物”,所以[A]正确。[B]只是其中一个方面,不够全面。[C]在最后一段提到,并不是本文的主体部分。文章通篇在介绍这种新的方法的积极意义,副作用只是一个方面.并不是通篇主旨,故[D]不正确。
转载请注明原文地址:https://kaotiyun.com/show/x0d4777K
0
考研英语一
相关试题推荐
WelearnfromthefirstparagraphthatAccordingtothetext,whatconcernstheauthormostisthe______withrespecttocloni
TheTheoryofContinentalDrifthashadalongandturbulenthistorysinceitwasfirstproposedbyAlfredWegenerin1910.(46)
Inthefollowingtext,somesentenceshavebeenremoved.ForQuestions41-45,choosethemostsuitableonefromthelist(A、B、C、
Theenvironmentalandsocialcostsofclosingandrehabilitating(恢复)oldandabandonedminesaroundtheworldarelikelyintril
Theenvironmentalandsocialcostsofclosingandrehabilitating(恢复)oldandabandonedminesaroundtheworldarelikelyintril
Inthefollowingtext,somesentenceshavebeenremoved.ForQuestions41-45,choosethemostsuitableonefromthelist(A、B、C、
Theinitialfundofgeneralscientificknowledgeisaninvaluableasset(财产),buttheyoungresearchworkershouldhavenoillusi
What’stheauthor’sattitudetowardstheUFOs?Itisconcludedfromthepassagethatthetestimonygivenbyoneortwopersons
"WewantSingaporetohavetheX-factor,thatbuzzthatyougetinLondon,Paris,orNewYork".ThatishowLeeHsienLoong,Sin
Whatisthepassagemainlyabout?Whatcanyouconcludefromthelastsentenceofthepassage?
随机试题
当全球一体化的压力低、当地化的压力低时,跨国企业将采取()的竞争策略。
甲因涉嫌私分国有资产罪被检察机关依法逮捕,在侦查期间,甲想找一个律师,下列说法正确的有:()
某项目部对承建的重力式方块码头进行安装施工。问题:标准中对方块安装有什么强制性规定?
银行风险管理流程包括的环节有()。
一旅游团于某日18时入住饭店后,地陪要做好()等工作。()
教育学研究的任务是()。
最近,一位历史学家在研究的过程中,发现了两份提到同一个人——ErichSchnitzler的资料,其中一份标明的日期是1739年5月3日,是一份Schnitzler由于未经允许沿街叫卖而被逮捕的记录。第二份未标明日期,是一份Schnitzler宜称他已经
学生教学管理系统、图书管理系统都是以______为基础和核心的计算机应用系统。
TheImpactofWildernessTourismA)Themarketfortourisminremoteareasisboomingasneverbefore.Countriesallacrossthew
Twotypesoftestsarecommonlyusedinmodernschools.Thefirst【C1】______issometimescalledan"【C2】______"test.Itisinten
最新回复
(
0
)