首页
登录
职称英语
Researchers have made significant technological progress toward incr
Researchers have made significant technological progress toward incr
游客
2024-01-11
30
管理
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. [br] Which of the following hypothetical discoveries, if made, would be most likely to reduce the technical difficulties in producing plastic from organic crops?
选项
A、a source of refining fossil fuels that significantly reduces their cost to plastic manufacturers
B、a way of maintaining grain yields while producing high quantities of plastic that do not interfere with the functioning of plant chloroplasts
C、a means of reducing the clean-up cost of environmental damage wrought by CO2 and SO2 emissions
D、a means of yielding greater efficiency from coal-based fuels used in the organic plastic-production process
E、the discovery of a renewable source of plant-sugar that would lessen reliance on fossil fuels in organic plastic-manufacture
答案
B
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3353059.html
相关试题推荐
A、Emotionalexpressionvariesbetweenindividualstoasignificantlygreaterext
LAG:A、appeardifficultB、altersignificantlyC、dartsimplyD、gazeaboutE、movef
PATINA:A、inherentfeatureB、insignificantscrutinyC、coincidentalhappeningD、ne
Although______fellowinthepubliceye,Maxwellhasaproclivitytowardexpressi
Trendstowardreformhighlighttheinternationalappealofdecentra
HopefullyscientificprogressinAIDSresearchwillcontinueat______pace,butn
Inthe1650’sthepacifistQuakersbecameprogressively______withCromwell’sreg
Smithis______,tothedegreethatheseldomdisguiseshiscontempt______towards
LAG:A、appeardifficultB、altersignificantlyC、dartsimplyD、gazeaboutE、movef
SURMOUNT:ABOVE::A、insert:acrossB、permeate:throughC、deviate:towardD、ce
随机试题
Onstage,theforceofCarrick’spersonalityandthevividnessofhisactingdis
Thelate-nightbusisback!BeginningThursday,September30,late-nighttra
[originaltext]Ifyouarelikemostpeople,yourintelligencevariesfromse
临床护理的服务对象是A.家庭B.全社会C.单位团体D.社区的全体居民E.个人自己
仪器设备的示值是2.9,修正因子是1.2,则仪器设备的测量值应为()。A.
婴儿9个月,体重8kg,中度脱水,血清钠136mmol/L,第一天的补液总量为A
对标准品的要求不包括A.其量值可溯源准确性高 B.基质效应小 C.无传染危险
下表所示为一个有四种实验处理的设计方案。该研究设计属于 A.匹配设计 B.A
在工程网络计划中,判断其关键工作与关键线路的方法是()。A:自由时差为零的工作是
“受试者根据自己的理解和感受,对一些意义不明的图象,墨迹做出回答,借以诱导出受试
最新回复
(
0
)