GRE阅读题目解析:昆虫帮助苏铁传粉

　　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.

　　P3

　　1

　　Experiments show that insects can function as pollinators of cycads, rare, palmlike tropical plants.

　　实验显示昆虫可以帮助苏铁传粉，后者是一种稀有的，手掌形状的热带植物。

　　cycad 苏铁，俗称铁树

　　2

　　Furthermore, cycads removed from their native habitats - and therefore from insects native to those habitats - are usually infertile.

　　此外，离开了原栖息地的苏铁 —— 所以是被昆虫带过去的 —— 往往无法结果。

　　3

　　Nevertheless, anecdotal reports of wind pollination in cycads cannot be ignored.

　　然而，一些关于苏铁风媒传粉的好玩报告不可忽略。

　　4

　　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.

　　苏铁雄球花的结构，相当符合花粉随风散落的模式，较大的雄球花会释放出花粉云。

　　5

　　The male cone of Cycas circinalis, for example, sheds almost 100 cubic centimeters of pollen, most of which is probably dispersed by wind.

　　比如说卷圈苏铁的雄球花，所释放的 100 立方厘米花粉，大部分可能是通过风散布的。

　　6

　　Furthermore, the structure of most female cycad cones seems inconsistent with direct pollination by wind.

　　另外，多数苏铁的雌球花似乎不配合直接的风媒传粉。

　　7

　　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)

　　只有 Cycas 属雌球花的胚珠能够接触到风携带的花粉，因为只有这个属的胚珠被大孢子叶丛松散地包围，而非紧凑的雌球花。

　　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.

　　选 C

　　A 错在 conclusive 和 one，证据有两个：

　　首先开篇就告诉我们，昆虫可以给苏铁传粉;

　　另外，句 5：

　　The male cone of Cycas circinalis, for example, sheds almost 100 cubic centimeters of pollen, most of which is probably dispersed by wind.

　　从 probably 也能暗示我们受粉的方式未必是 in favor of one particular explanation 的。

　　B

　　说反了也说错了。

　　文中告诉我们，雄球花 male cone 是配合风媒传粉的 quite consistent，而雌球花 female cone 是闹别扭的 seems inconsistent with direct pollination by wind ;

　　即便 B 把雌雄换位，仍然不成立，seems 拒绝了一种方式，不代表拒绝所有的方式，起码文章中就提到虫可以牵线。

　　rule out 排除，根除，防止

　　C

　　正确，分别在句 4、6：

　　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.

　　...

　　Furthermore, the structure of most female cycad cones seems inconsistent with direct pollination by wind.

　　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.

　　选 D

　　再看一遍句 2：

　　Furthermore, cycads removed from their native habitats - and therefore from insects native to those habitats - are usually infertile.

　　理一理思路：

　　苏铁作为一种植物，首先它得有一部分能够正常生育，否则它早就灭绝了;

　　而虫帮助授粉的苏铁，多数不育;

　　结合后文提到的风媒传粉，我们有理由猜测，风媒传粉的苏铁，与能够正常生育的苏铁，重合度比较高。

　　综上，看选项：

　　A 只有很少几种苏铁可以被成功移植。无法判断是能够移植的种类少，还是数量少，还是其他别的原因，比如 D 提示的原因。

　　B 除了风和虫，苏铁还有其他方式授粉。无关项，它不能帮我们解释句 2 提出的 fact 。

　　C 迁居的苏铁，被当地一些虫吃了。可能正确但不够严谨，首先你得确保虫能吃光这个外来物种(你看看那个图片，难度很高的)，另外，不育和被吃光来不及生育是两码事，有 tiny 可能正确，但不够严谨。

　　D 通常苏铁成功迁居的地区，有着和原栖息地相似的风。正确项。根据我们上面的推测，尽管虫也能让苏铁授粉，但风媒传粉显然对苏铁来说更靠谱。有相似的风，就能通过风煤传粉，也就能成功生育，而昆虫携带的苏铁，因为当地的风不适合苏铁授粉，都没有结果。

　　E 苏铁的迁居，可能伴随着某种虫的去来。可能正确，但无关，它无法解释句 2 提出的，为什么虫带走的苏铁不育。