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毛毛虫是这个吧？？
GWD-13-Q34 -Q37是谁控制着毛毛虫的生命长度
A small number of the forest
species of lepidoptera (moths and
butterflies, which exist as caterpillars
Line during most of their life cycle) exhibit
(5) regularly recurring patterns of popu- 现象：毛虫有循环的数量变化
lation growth and decline—such 周期。究其原因
fluctuations in population are known
as population cycles. Although many
different variables influence popula-
(10) tion levels, a regular pattern such as
a population cycle seems to imply a
dominant, driving force. Identification
of that driving force, however, has 旧研究方法：不同捕食者造成
proved surprisingly elusive despite 的死亡率。-失败。
(15) considerable research. The com-
mon approach of studying causes of
population cycles by measuring the
mortality caused by different agents,
such as predatory birds or parasites,
(20) has been unproductive in the case of
lepidoptera. Moreover, population 旧研究方法：使毛虫搬家。
ecologists’ attempts to alter cycles -也失败。
by changing the caterpillars’ habitat
and by reducing caterpillar popula-
(25) tions have not succeeded. In short,
the evidence implies that these insect
populations, if not self-regulating, may 所以一定另有他因。
at least be regulated by an agent more
intimately connected with the insect than
(30) are predatory birds or parasites.老观点及其方法
Recent work suggests that this 近期研究发现根源是病毒。以前
agent may be a virus. For many 以为病毒只是推波助澜而非
years, viral disease had been 罪魁祸首。
reported in declining populations
(35) of caterpillars, but population ecolo-
gists had usually considered viral
disease to have contributed to the
decline once it was underway rather
than to have initiated it. The recent
(40) work has been made possible by
new techniques of molecular biology
that allow viral DNA to be detected
at low concentrations in the environ-
ment. Nuclear polyhedrosis viruses
(45) are hypothesized to be the driving 病毒叫Np。它自身有一个感染
force behind population cycles in 周期。先是藏在蛋白质晶体里，
lepidoptera in part because the 毛虫吃晶体，病毒释放，虫死，
viruses themselves follow an infec- 大量有毒蛋白质晶体又产生并
tious cycle in which, if protected from 渗入大地。如此往复。
(50) direct sun light, they may remain
virulent for many years in the envi-
ronment, embedded in durable
crystals of polyhedrin protein.
Once ingested by a caterpillar,
(55) 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
(60) crystals. These crystals reenter the
environment after the insect dies and
decomposes, thus becoming avail-
able to infect other caterpillars.新观点及其论据
One of the attractions of this 支持病毒论，因为它适用于很多
(65) hypothesis is its broad applicability. 情况。
Remarkably, despite significant differ-
ences in habitat and behavior, many
species of lepidoptera have population
cycles of similar length, between eight
(70) and eleven years. Nuclear polyhe-
drosis viral infection is one factor these
disparate species share.新观点正评价
老新观点
1P: population cycle, identify driving force, however, surprising elusive. Common approach unproductive; ecologist’s attempt, not succeed. In short, population regulated by intimated connected with insects.
2P: recent work suggest virus. Contributed to. Recent work made possible by new techniques. NP hypothesized because…
3P: attractions of hypothesis is ….
--------------------------------------------------------------------------------
T-9-20:GWD-13-34:
Which of the following, if true, would most weaken the author’s conclusion in lines 25-30?
A. New research reveals that the number of species of birds and parasites that prey on lepidoptera has dropped significantly in recent years.
B. New experiments in which the habitats of lepidoptera are altered in previously untried ways result in the shortening of lepidoptera population cycles.
C. Recent experiments have revealed that the nuclear polyhedrosis virus is present in a number of predators and parasites of lepidoptera.
D. Differences among the habitats of lepidoptera species make it difficult to assess the effects of weather on lepidoptera population cycles.
E. Viral disease is typically observed in a large proportion of the lepidoptera population.
--------------------------------------------------------------------
T-9-21:GWD-13-35:
It can be inferred from the passage that the mortality caused by agents such as predatory birds or parasites was measured in an attempt to
A. develop an explanation for the existence of lepidoptera population cycles
B. identify behavioral factors in lepidoptera that affect survival rates
C. identify possible methods for controlling lepidoptera population growth
D. provide evidence that lepidoptera populations are self-regulating
E. determine the life stages of lepidoptera at which mortality rates are highest
--------------------------------------------------------------------
T-9-22:GWD-13-36:
The primary purpose of the passage is to
A. describe the development of new techniques that may help to determine the driving force behind population cycles in Lepidoptera
B. present evidence that refutes a particular theory about the driving force behind population cycles in Lepidoptera
C. present a hypothesis about the driving force behind population cycles in Lepidoptera
D. describe the fluctuating patterns of population cycles in Lepidoptera
E. question the idea that a single driving force is behind population cycles in Lepidoptera
--------------------------------------------------------------------
T-9-23:GWD-13-37:
According to the passage, before the discovery of new techniques for detecting viral DNA, population ecologists believed that viral diseases
A. were not widely prevalent among insect populations generally
B. affected only the caterpillar life stage of lepidoptera
C. were the driving force behind lepidoptera population cycles
D. attacked already declining caterpillar populations
E. infected birds and parasites that prey on various species of Lepidoptera
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发表于 2013-3-16 15:46:41
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