[CASK EFFECT] 难度【LSAT】1-27 解读

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题目请参考

【CASK EFFECT】1006G阅读全方位锻炼--难度【LSAT】--答题解读汇总

答案：BDCEAD
15(B)
本题讨论“the main idea of the passage”
全文分析：
开篇提出农业问题：Cultivation of a single crop on a given tract of land leads eventually to decreased yields
然后通过简单例子引出“These improvements in crop yields through the application of Pseudomonas fluorescens suggest that agriculture could benefit from the use of bacteria genetically altered for specific purposes.”，并引发“proponents”与“oponents”间的争论，但作者更加倾向proponents，于是再提出
“Some proponents have gone further and suggest that genetic alteration techniques could create organisms with totally new combinations of desirable traits not found in nature”，“These prospects lead many to hope that current efforts to assess the risks of deliberate release of altered microorganisms will successfully answer the concerns of opponents and create a climate in which such research can go forward without undue impediment.”
综上所述，
作者通过experiment/controversy力挺genetic alteration techniques在crop中的应用及好处，注意作者并没有谈及可能的danger
“Encouraged by current research, advocates of agricultural use of genetically altered bacteria are optimistic that such use will eventually result in improved agriculture, though opponents remain wary”

16(D)
根据“naturally occurring Pseudomonas fluorescens bacteria in the first paragraph”定位原文
“However, even if crops are not rotated, the severity of diseases brought on by such phytopathogens often decreases after a number of years as the microbial population of the soil changes and the soil becomes “suppressive” to those diseases. While there may be many reasons for this phenomenon, it is clear that levels of certain bacteria, such as Pseudomonas fluorescens, a bacterium antagonistic to a number of harmful phytopathogens, are greater in suppressive than in nonsuppressive soil.”作者为了证明红色字体而引入PF，并在后文提到“There is now considerable experimental support for this view.”说明这种提高crop yields的方法比较有吸引力，有效果
“provide background information to support the argument that research into the agricultural use of genetically altered bacteria would be fruitful”注意关键词的把握

17(C)
根据“crops impervious to parasitical organisms”定位原文
“One reason for this is that harmful bacterial phytopathogens, organisms parasitic on plant hosts, increase in the soil surrounding plant roots”，推断出作者下文所有的分析均针对crops pervious to parasitical organisms，如果是impervious crops，下面的讨论将没有意义
即
“Their yield would not be likely to be improved by adding Pseudomonas fluorescens bacteria to the soil”

18(E)
根据“crop rotation can increase yields in part”定位原文
“The problem can be cured by crop rotation, denying the pathogens a suitable host for a period of time.”
即
“phytopathogens typically attack some plant species but find other species to be unsuitable hosts”宿主关系一定要提到

19(A)
根据“proponents”“the altered bacteria used in the frost-damage experiments”定位原文
“Proponents, on the other hand, argue that this particular strain is altered only by the removal of the gene responsible for the strain’s propensity to cause frost damage, thereby rendering it safer than the phytopathogen from which it was derived.”

通过比较“, a form of phytopathogen altered to remove its harmful properties could be released into the environment in quantities favorable to its competing with and eventually excluding the harmful normal strain.”，得出strain是指a form of phytopathogen
即
“The altered bacteria had a genetic constitution differing from that of the normal strain only in that the altered variety had one less gene.”

20(D)
根据“weaken the proponents’ argument regarding the safety of using altered Pseudomonas syringae bacteria to control frost damage”定位原文
“Proponents, on the other hand, argue that this particular strain is altered only by the removal of the gene responsible for the strain’s propensity to cause frost damage, thereby rendering it safer than the phytopathogen from which it was derived”
可以推断出proponents认为只是减少一种gene，没有其它deleterious results
选项(D)反驳最为有力
“Often genes whose presence is responsible for one harmful characteristic must be present in order to prevent other harmful characteristics.”