|
. Amphibian populations are declining in numbers worldwide. Not coincidentally, the earth’s ozone layer has been continuously depleted throughout the last 50 years. Atmospheric ozone blocks UV-B, a type of ultraviolet radiation that is continuously produced by the sun, ad which can damage genes. Because amphibians lack hair, hide, or feathers to shield them, they are particularly vulnerable to UV-B radiation. In addition, their gelatinous eggs lack the protection of leathery or hard shells. Thus, the primary cause of the declining amphibian population is the depletion of the ozone layer. Each of the following, if true, would strengthen the argument EXCEPT: A. Of the various types of radiation blocked by atmospheric ozone, UV-B is the only type that cn damage genes. B. Amphibian populations are declining far more rapidly than are the populations of non-amphibian species whose tissues and eggs have more natural protection from UV-B. C. Atmospheric ozone has been significantly depleted above all the areas of the world in which amphibian populations are declining. D. The natural habitat of amphibians has not become smaller over the past century. E. Amphibian populations have declined continuously for the last 50 years.
给出的答案是
D 但是我觉得答案应该是A 我是这样想的：如果在过去的50年里面am这个东西的自然栖息地明没有减少，就可以排除是栖息地减少而引起的种群数量的减少。从而支持结论数量的减少是由于臭氧层的破坏引起的。而A选项，UV-B是不是唯一破坏基因的射线其实都没有关系，因为结论说的是臭氧层减少和生物数量减少的关系，而不死UV-B和种群数量减少的关系 | 
京公网安备11010202008513号 京ICP证101109号 京ICP备12012021号
发表于 2013-10-15 22:17:55
收藏
收藏
