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Extinction is a process that can depend on a variety of ecological, geographical, and physiological variables.These variables affect different species of organisms in different ways, and should, therefore, yield a random pattern of extinctions.However, the fossil record shows that extinction occurs in a surprisingly definite pattern, with many species vanishing at the same time.

Which of the following, if true, forms the best basis for at least a partial explanation of the patterned extinctions revealed by the fossil record?

正确答案: A

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楼主
发表于 2004-10-15 01:11:00 | 只看该作者

OG-57有疑问 请大家帮忙

57. Extinction is a process that can depend on a variety of ecological, geographical, and physiological variables.



These variables affect different species of organisms in different ways, and should, therefore, yield a random pattern of extinctions. However, the fossil record shows that extinction occurs in a surprisingly definite pattern, with many species vanishing at the same time.



Which of the following, if true, forms the best basis for at least a partial explanation of the patterned extinctions revealed by the fossil record?



(A) Major episodes of extinction can result from widespread environmental disturbances that affect numerous different species.



(B) Certain extinction episodes selectively affect organisms with particular sets of characteristics unique to their species.



(C) Some species become extinct because of accumulated gradual changes in their local environments.



(D) In geologically recent times, for which there is no fossil record, human intervention has changed the pattern of extinctions.



(E) Species that are widely dispersed are the least likely to become extinct.





A is the best answer.



Choice A, the best answer, asserts that some environmental disturbances can be so widespread as to cause the extinction of numerous species. This fact helps to explain why the fossil record frequently shows many species becoming extinct at the same time, despite the variety of factors that can cause a species to become extinct.





想请教各位,小的不懂为什么A选项可以解释文中矛盾之处,另外,也不太了解highlight的解释,请各位指教,谢谢!!

沙发
发表于 2004-10-15 04:29:00 | 只看该作者
总结题意:物种灭绝由一系列的生态地理生理变化引起,而这些变化对不同种类的生物产生的影响不同。所以,各种应该有多种形式的灭绝。但是从化石显示,物种灭绝却有一定的模式,即很多物种同时消失。

A  主要的extinction都是由于大范围的环境突变引起,而这种环境变化对不同物种同时产生影响,很好的解释了多物种同时消失的原因。

板凳
发表于 2009-1-5 11:14:00 | 只看该作者
这道题我做题时题目就没读明白,还以为是应该是多个物种应该都可能没绝,但是每次只有特别的物种灭绝
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