标题: OG 134 [打印本页] 作者: hdrtrw112 时间: 2004-9-7 12:36 标题: OG 134
134. Caterpillars of all species produce an identical hormone called "juvenile hormone" that
maintains feeding behavior. Only when a caterpillar has grown to the right size for pupation
to take place does a special enzyme halt the production of juvenile hormone. This enzyme
can be synthesized and will, on being ingested by immature caterpillars, kill them by
stopping them from feeding.
Which of the following, if true, most strongly supports the view that it would not be advisable
to try to eradicate agricultural pests that go through a caterpillar stage by spraying
croplands with the enzyme mentioned above?
(A) Most species of caterpillar are subject to some natural predation.
(B) Many agricultural pests do not go through a caterpillar stage.
(C) Many agriculturally beneficial insects go through a caterpillar stage.
(D) Since caterpillars of different species emerge at different times, several sprayings
would be necessary.
(E) Although the enzyme has been synthesized in the laboratory, no large-scale production
facilities exist as yet. 我觉得B,C 都可以啊,相不明白为什么答案是C,B为什么不可以啊?作者: himba 时间: 2004-9-7 12:36
hehe, Why B is correct? B is only to say not all pests with a caterpicllar stage, but it would not affect the action to use enzyme to kill other pests which go through such stage....
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