【OG24-536题】According to the passage, nuclear polyhedrosis viruses can remain virulent in the environment only when_mofa留学圈mofaGRE在线题库系统_GRE在线搜题_GRE题库解析_GRE真题机经_GRE课程_GRE培训机构

最新题目

题目内容

纠错

A small number of the forest species of lepidoptera (moths and butterflies, which exist as caterpillars during most of their life cycle) exhibit regularly recurring patterns of population growth and decline—such fluctuations in population are known as population cycles. Although many different variables influence population levels, a regular pattern such as a population cycle seems to imply a dominant, driving force. Identification of that driving force, however, has proved surprisingly elusive despite considerable research. The common approach of studying causes of population cycles by measuring the mortality caused by different agents, such as predatory birds or parasites, has been unproductive in the case of lepidoptera. Moreover, population ecologists’ attempts to alter cycles by changing the caterpillars’ habitat and by reducing caterpillar populations have not succeeded. In short, the evidence implies that these insect populations, if not self-regulating, may at least be regulated by an agent more intimately connected with the insect than are predatory birds or parasites.

Recent work suggests that this agent may be a virus. For many years, viral disease had been reported in declining populations of caterpillars, but population ecologists had usually considered viral disease to have contributed to the decline once it was underway rather than to have initiated it. The recent work has been made possible by new techniques of molecular biology that allow viral DNA to be detected at low concentrations in the environment. Nuclear polyhedrosis viruses are hypothesized to be the driving force behind population cycles in lepidoptera in part because the viruses themselves follow an infectious cycle in which, if protected from direct sunlight, they may remain virulent for many years in the environment, embedded in durable crystals of polyhedrin protein. Once ingested by a caterpillar, the crystals dissolve, releasing the virus to infect the insect’s cells. Late in the course of the infection, millions of new virus particles are formed and enclosed in polyhedrin crystals. These crystals reenter the environment after the insect dies and decomposes, thus becoming available to infect other caterpillars.

One of the attractions of this hypothesis is its broad applicability. Remarkably, despite significant differences in habitat and behavior, many species of lepidoptera have population cycles of similar length, between eight and 11 years. Nuclear polyhedrosis viral infection is one factor these disparate species share.

According to the passage, nuclear polyhedrosis viruses can remain virulent in the environment only when

the polyhedrin protein crystals dissolve caterpillar populations are in decline they are present in large numbers their concentration in a particular area remains low they are sheltered from direct sunlight

正确答案： E

参考解析

提交我的解析

文章大意逻辑
文章开篇指出鳞翅目（飞蛾和蝴蝶）的一些森林物种存在定期的种群数量增长和下降模式（种群周期），虽然很多变量影响种群数量，但找到种群周期背后的主导驱动因素很困难。传统研究方法对鳞翅目无效，改变栖息地和减少数量的尝试也未成功，暗示可能存在与昆虫联系更紧密的调节因素。接着提出新观点：这种因素可能是病毒。过去生态学家认为病毒是在种群数量下降过程中起作用而非引发下降，而新技术使检测低浓度病毒DNA成为可能。最后说明核多角体病毒被假设为种群周期背后驱动力的部分原因是其自身的感染周期，在免受阳光直射时可在环境中保持毒性多年。 文章类型及逻辑简图
文章类型：新旧观点对比 逻辑简图 Old view: Many variables influence population levels, traditional study methods unproductive for lepidoptera, population ecologists' attempts failed. New view: A virus may be the driving force behind population cycles. Viral DNA can be detected by new techniques. Nuclear polyhedrosis viruses can remain virulent under certain conditions. 做题方法及问题类型
这是一道细节题，通过定位关键词“nuclear polyhedrosis viruses”以及“remain virulent in the environment only when”来解题。 选项分析
A选项：文中未提及多角体蛋白晶体溶解与病毒保持毒性的关联，属于无中生有，排除。 B选项：毛虫种群数量下降和病毒保持毒性没有直接联系，排除。 C选项：文中没有提到病毒数量多与保持毒性的关系，排除。 D选项：文中未提及病毒在特定区域浓度低和保持毒性的关系，排除。 E选项：对应原文“if protected from direct sunlight, they may remain virulent for many years in the environment”，说明病毒免受阳光直射时可保持毒性，该项正确。

题目讨论 (如果对题目有任何的疑惑，欢迎在这里提出来，大家会帮你解答的哦~)

还没有人评论,赶快抢个沙发~

做题笔记

参考解析

题目讨论 (如果对题目有任何的疑惑，欢迎在这里提出来，大家会帮你解答的哦~)

请选择错误类型：

请描述一下这个错误：