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
Researchers have made significant technological progress toward increasing the amount of plastic that plants can grow and
Researchers have made significant technological progress toward increasing the amount of plastic that plants can grow and
admin
2011-01-17
84
问题
Researchers have made significant technological progress toward increasing the
amount of plastic that plants can grow and altering the composition of the plastic to
endow it with useful properties, but achieving both a useful
Line composition and high plastic content in the plant proves to be a formidable task.
(5) The chloroplasts of the leaves have so far shown themselves to be the best
location for producing plastic, but the chloroplast is the green organelle that
captures light, and high concentrations of plastic could thus inhibit
photosynthesis and reduce grain yields, and the challenges of separating the
plastic from the plant are awesome. Given sufficient time and funding,
(10) researchers could overcome these technical obstacles, but a greater concern has
made us question whether those solutions are worth pursuing. When calculating
all the energy and raw materials required for each step of growing a
biodegradable plastic made from plant sugar polyhydroxyalkanoate in plants, we
discovered that this approach would consume even more fossil resources than
(15) most petrochemical manufacturing routes.
In a recent study, scientists found that making one kilogram of
polyhydroxyalkanoate from genetically modified corn plants would require about
300 percent more energy than the 29 megajoules needed to manufacture an
equal amount of fossil fuel-based polyethylene (PE). Given this comparison, it
(20) is impossible to argue that plastic grown in corn and extracted with energy from
fossil fuels would conserve fossil resources. What is gained by substituting the
renewable resource for the finite one is lost, through a tremendous irony, in
the additional requirement for energy. Fueling this process requires 20 to 50
percent fewer fossil resources than does making plastics from petroleum, but it
(25) is still significantly more energy intensive than most petrochemical processes
are, even though developing alternative plant-sugar sources that require less
energy to process, such as wheat and beets, would eventually attenuate the use
of fossil fuels.
The energy necessary for producing plant-derived plastics gives rise to a
(30) second, perhaps even greater, environmental concern: fossil petroleum is the
primary resource for conventional plastic production, but making plastic from
plants depends mainly on coal and natural gas used to power the corn-farming
and corn-processing industries. Any of the plant-based methods, therefore,
involves switching from a less abundant fuel (petroleum) to a more abundant
(35) one (coal). Some experts argue that this switch is a step toward sustainability.
Missing in this logic, however, is the fact that all fossil fuels used to make
plastics from renewable raw materials (corn) must be burned to generate
energy, whereas the petrochemical processes incorporate a significant portion
of the fossil resource into the final product. Burning more fossil fuels
(40) exacerbates an established global climate problem by increasing emissions of
greenhouse gases, such as CO2, and SO2, which contribute to acid rain; thus
the environmental benefit of growing plastic in plants is overshadowed by
unjustifiable increases in energy consumption and gas emissions.
It can be inferred from the passage that which of the following was the prime goal in scientists’ searching for organic means of producing plastic?
选项
A、the reduction of energy used in petrochemical plastic manufacture
B、the reduction of the production cost of petrochemical manufacture
C、the development of a biodegradable plastic
D、the creation of plastics with more useful qualities
E、the reduction of fossil fuel emissions in the environment
答案
C
解析
转载请注明原文地址:https://kaotiyun.com/show/MHjO777K
本试题收录于:
GRE VERBAL题库GRE分类
0
GRE VERBAL
GRE
相关试题推荐
Beforejoiningthearmy,hespentalotoftimeinthevillage______hebelonged.
Throughouthistory,humanshavesufferedfromaconditionthattheyhaveneverbeenabletoescape——ageing.Someresearchers,ho
Icannot______thetruthofyourwords,althoughtheygoagainstmyinterests.
Inthe1850’sHarrietBeecherStowe’s"UncleTom’sCabin"becamethebestsellerofthegeneration,________ahostofimitators.
Inacertainconservativemutualfund,70percentofthemoneyisinvestedinbonds,andofthatportion,40percentisinvested
Theauthorindicatesexplicitlythatwhichofthefollowingrecordshasbeenasourceofinformationinherinvestigation?Int
MARGIN:PAGE::
FACILITATE:
AFFINITY:
Theoldmancouldnothavebeenaccusedof(i)____hisaffection;hisconducttowardthechildbetrayedhis(ii)____her.
随机试题
血中PCO2升高对呼吸运动有何影响?试述其调节过程。
十滴水使用时需注意()。
A.针晶B.砂晶C.簇晶D.方晶E.柱晶甘草含
关于国家环境标准与地方环境标准的关系,说法正确的是()。
背景材料:某公司(甲方)与某建筑公司(乙方)订立了桥梁基础施工合同,同时又与丙方订立了工程降水合同,基础施工合同约定采用综合单价承包。该基础工程施工网络计划如下图所示。甲乙双方约定某年6月15日开工,在工程施工中发生了如下事件。事件一:由于降水施工
某区房产管理局向郭某发放了一份房屋产权证书,郭某系房屋产权人。李某知道此事后非常气愤,声称自己几年前就从该区房产管理局领到了所涉房产的产权证书。因交涉没有结果,李某遂以房屋产权人的名义向区政府申请复议,请求撤销区房产管理局向郭某发放的房屋产权证书。经复议审
在下列()情形下,项目从经济资源配置的角度考虑可以被接受。
A男与B女在离婚协议中约定:为了婚生女小萍的健康成长,B女若再婚也不可再生育子女,该约定违反了哪一项原则?()[2019年法考真题]
软件维护的副作用主要有以下(21)几种。
PASSAGEONEWhydidtheauthorgobacktotheDevonschool?
最新回复
(
0
)