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GRE阅读题目解析:昆虫帮助苏铁传粉

2017-07-19 08:25:00来源:网络

  GRE阅读题目解析:昆虫帮助苏铁传粉】GRE考试考什么?GRE阅读是重点。新东方在线GRE频道为大家带来GRE阅读题目解析:昆虫帮助苏铁传粉,答案见下一页,希望对大家GRE备考有所帮助。更多精彩尽请关注新东方在线GRE频道!

  查看全部:GRE阅读答案解析(汇总)

  GRE阅读题目解析:昆虫帮助苏铁传粉

  P3

  Experiments show that insects can function as pollinators of cycads, rare, palmlike tropical plants. Furthermore, cycads removed from their native habitats - and therefore from insects native to those habitats - are usually infertile. Nevertheless, anecdotal reports of wind pollination in cycads cannot be ignored. The structure of cycads male cones is quite consistent with the wind dispersal of pollen, clouds of which are released from some of the larger cones. The male cone of Cycas circinalis, for example, sheds almost 100 cubic centimeters of pollen, most of which is probably dispersed by wind. Furthermore, the structure of most female cycad cones seems inconsistent with direct pollination by wind. Only in the Cycas genus are the females' ovules accessible to airborne pollen, since only in this genus are the ovules surrounded by a loose aggregation of megasporophylls rather than by a tight cone. (141 words)

  For the following question, consider each of the choices separately and select all that apply

  6. The passage suggests that which of the following is true of the structure of cycad cones?

  (A) The structure of cycad cones provides conclusive evidence in favor of one particular explanation of cycad pollination.

  (B) The structure of male cycad cones rules out a possible mechanism for cycad pollination that is suggested by the structure of most female cycad cones.

  (C) The structure of male cycad cones is consistent with a certain means of cycad pollination, but that means is inconsistent with the structure of most female cycad cones.

  7. The evidence in favor of insect pollination of cycads presented in the second sentence would be more convincing if which of the following were also true?

  (A) Only a small variety of cycad species can be successfully transplanted.

  (B) Cycads can sometimes be pollinated by means other than wind or insects.

  (C) Insects indigenous to regions to which cycads are transplanted sometimes feed on cycads.

  (D) Winds in the areas to which cycads are usually transplanted are similar to winds in cycads' native habitats.

  (E) The transplantation of cycads from one region to another usually involves the accidental removal and introduction of insects as well.

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