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
93
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.
The passage implies that which of the following is true of the petrochemical means of plastic production?
选项
A、New advances in petrochemical plant manufacture could potentially lessen the process’ reliance on fossil fuel sources.
B、The fossil fuel resources incorporated in its products are less wasteful and environmentally damaging than the gas emissions produced by plant-based plastic production.
C、Petrochemical plant manufacture is generally more sustainable in environmental terms than plant-based plastic production.
D、Petrochemical plant manufacture generally depends on the most abundant fuel source available.
E、Petrochemical plant manufacture does not share in fuel sources in common with plant-based plastic production.
答案
B
解析
转载请注明原文地址:https://kaotiyun.com/show/0HjO777K
本试题收录于:
GRE VERBAL题库GRE分类
0
GRE VERBAL
GRE
相关试题推荐
Lucia:Doyouhaveanytissue,Polly?Polly:Here.______Lucia:Thanks.Ihaveaterribleheadache.Itseemstobeflu.
Halfoftheworld’scoralreefs(珊瑚礁)havediedinthelast30years.Nowscientistsareracingtoensurethattherestsurvive
______evidencethatlanguage-acquiringabilitymustbestimulated.
NeitherhisfellowworkersnorTodhimself______tothesolutionputforwardbytheemployer.
Itwasin2005______webegantointroducethisnewtechniqueintoourcompany.
Traditionally,universitieshavecarriedouttwomainactivities:researchandteaching.Manyexpertswouldarguethatboththes
Traditionally,universitieshavecarriedouttwomainactivities:researchandteaching.Manyexpertswouldarguethatboththes
Howfitareyourteeth?Areyoulazyaboutbrushingthem?Neverfear:Aninventorisonthecase.Anelectrictoothbrushsenses
Twodivergentdefinitionshavedominatedsociologists’discussionsofthenatureofethnicity.Thefirstemphasizestheprimordi
Toensureconsistentlyhighqualityinitsmerchandise,thechainofretailstoresbecameinvolvedineveryaspectoftheirsupp
随机试题
自然环境与人口是社会存在和发展的自然前提、必要条件。()
设曲线方程为,则y=__________。
耻骨肌受______________神经和______________神经支配。
甲、乙两公司签订一份100万元的建材买卖合同,约定购货方交付20万元作为定金。如果供货方交付了50万元的货物后,没有按约定提供其余货物,供货方因违约双倍返还定金的数额为20万元。()
根据企业所得税法律制度的规定,下列固定资产中,在计算企业所得税应纳税所得额时准予扣除折旧费的是()。
2019年母公司向子公司销售一批商品,售价为20000元,销售成本为16000元;子公司购进的该商品本年全部未实现对外销售而形成年末存货。子公司年末发现该存货已部分陈旧,2019年年末存货可变现净值降至18400元。2020年母公司又向子公司销售一批
戴克里先
设子程序过程定义的首部为:PublicSubS(XAsInteger,YAsSingle)则以下正确的调用形式为
Microsoftisaworld-knowncorporationanditsmainproductissoftware.ThemanwhowillsoonbecomeMicrosoft’snewchief【B1】
【B1】【B7】
最新回复
(
0
)