皮皮学,免费搜题
登录
搜题
【单选题】
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 plan
A.
expose the fragile nature of the foundations on which bioengineering research rests
B.
argue that bioengineering is ultimately infeasible as a means of manufacturing plastic
C.
argue that the advances in organically-based plastic manufacture cannot solve environmental issues
D.
explain the reasons for and objectives of current research on the development of organically-based plastic manufacture
E.
describe the nature of the organic plastic manufacturing process
拍照语音搜题,微信中搜索"皮皮学"使用
参考答案:
参考解析:
知识点:
.
..
皮皮学刷刷变学霸
举一反三
【单选题】以下哪个不是可设置的墙的类型参数
A.
粗略比例填充样式
B.
复合层结构
C.
材质
D.
连接方式
【单选题】有关印度粮食生产的说法,错误的是
A.
众多的人口,使印度成为粮食消费大国
B.
从 20 世纪到现在,印度每年都要进口大量粮食
C.
20 世纪 60 年代,印度实行了“绿色革命”,改进了粮食生产技术,粮食供应状况逐步得到改善
D.
水稻和小麦是印度的主要粮食作物
【单选题】以下哪个不是可设置的墙的类型参数
A.
复合层结构
B.
材质
C.
连接方式
【单选题】采用装运港船上交货价的进口设备,估算其购置费时,货价按照( )计算。
A.
出厂价
B.
到岸价
C.
抵岸价
D.
离岸价
【单选题】有关印度粮食生产的说法,错误的是 [     ]
A.
众多的人口,使印度成为粮食消费大国
B.
从20世纪到现在,印度每年都要进口大量粮食
C.
水稻和小麦是印度的主要粮食作物
D.
20世纪60年代,印度实行了“绿色革命”,改进了粮食生产技术,粮食供应状况逐步得到改善
【单选题】荔枝不耐贮藏,正如(甲)说的:“一日而色变,二日而香变,三日而味变,四五日外,色香味尽去矣。”现经研究证实,温度保持在1°C到5°C,可贮藏30天左右。还应进一步设法延长贮藏期,以利于长途运输。因为荔枝不耐贮藏,古代宫廷想吃荔枝,就要派人兼程飞骑从南方远送长安或洛阳,给人民造成许多痛苦。唐明皇为了宠幸杨贵妃,就干过这样的事。唐代(乙)诗云:“长安回望绣成堆,山顶千门次第开。一骑红尘妃子笑,无人知是...
A.
白居易 杜牧
B.
李白 杜甫
C.
白居易 杜甫
D.
李白 杜牧
【简答题】据报道,4月9日下午青海省西宁市纺织品大楼发生重大火灾,火灾造成1人死亡. (1)纺织品大楼内存在许多可燃物质.下列物质属于可燃物质的是______(填序号) ①大理石板    ②保温泡沫塑料    ③陶瓷砖    ④棉麻纺织品 (2)据目击者说火灾的起因是大楼后面在电焊铁架子时而引发的.火灾中电焊铁架子为燃烧提供的条件是______(填序号).A.提供可燃物  B.使可燃物温度达到着火点    ...
【简答题】远途运输(小写)
【判断题】ARM处理器芯片内核的工作时钟与外设工作时钟一致。
A.
正确
B.
错误
【判断题】外墙保温有外墙外保温和外墙内保温,后者因为存在冷桥、占用建筑面积等因素于2004年7月1日起被限制使用。
A.
正确
B.
错误
相关题目: