雅思2012年4月28号阅读机经回顾（A类）Passage 2
| Reading Passage 2 | |
| Title: | Ants |
| Question types: | Multiple Choice Which paragraph contains the following information Detail Matching |
| 文章内容回顾 | 蚂蚁和真菌，选择题第一个选earlier study have no evidence, 后面选 D substance useful to humans。A leaf-cutter ants B lower ants C Both 第一个说吃烂蔬菜的是B, nest较小的是B, nest大的是A, 可以吃有害植物，有帮助的是A；配对题中 escovoplish的危害是后面H段好像还有comparison of 两种蚂蚁的nest, leaf蚂蚁比人类做的好的two things，leaf-cutter对环境影响，lower那个蚂蚁的优点等。 |
| 英文原文阅读 | Fungus-growing ants are only New World in distribution, indicating that the origin and subsequent radiation throughout the Neotropics occurred after the separation 中 华 考 试 网of South America from Africa (88). The ability to cultivate fungi has a single origin in ants (72,90), evolving from an ancestor that is believed to have been a generalist forager (57). The ants belong to the monophyletic tribe Attini (subfamily Myrmicinae), which is composed of 12 genera and approximately 210 described species (72; Table 1). The five most phylogenetically derived genera form a clade called the "higher attines," and the remaining seven genera, with approximately half of the species diversity, compose the "lower attines." Although all attine ants are referred to as fungus-growers, the two most phylogenetically derived genera, Acromyrmex and Atta, are more commonly known as leaf-cutter ants. The lower attines typically use dead vegetative debris as well as insect feces and corpses to manure their gardens; the higher attine genera Tra chymyrmex and Sericomyrmex typically use dead vegetable matter, whereas those of the genera Acromyrmex and Atta use mostly fresh leaves and flowers (Table 1). Fungus-growing ants are obligately dependent on their fungal cultivars. The fungus serves as the sole food source for the larvae and queen, while workers supplement this by feeding on plant sap (42,59,67). The general nutritional value of the fungi that the attine ants cultivate is not clear (see 57); however, the fungi cultivated by many members of the higher attines produce specialized structure called gongylidia that the ants preferentially feed on (52,66,87,88). Gongylidia are hyphal swellings that, at least among the fungi cultivated by leaf-cutters, are rich in lipids and carbohydrates (47,67). Fungus-growing ants, like all ants, are social, forming colonies of closely related individuals. Ant colonies have been described as "superorganisms" (34), with individual workers performing tasks for the functioning of the colony just as cells in higher organisms. The queen, of which there is usually only one, tends the garden in its incipient stage and subsequently reproduces the worker population; workers engage in tasks that help the colony function, such as foraging for food, cleaning the nest, caring for the brood, and defending against attackers; and males participate only in reproduction, dying shortly after the nuptial flight. The queen transfers the fungus into the next generation by carrying a small clump of the cultivar with her during the nuptial flight (35,36). This ball of fungus from the parent colony is stored in the queen's infrabuccal pocket, a cavity and filtering device within the mouthparts of ants (27). Once inseminated, the queen typically digs a clasutral chamber, spits-up the fungus, and begins tending it underground, although some species form new colonies under leaf litter or rocks, under or within logs, or even in trees (88). Prior to the presence of workers, growth of the fungus is supported by the foundress queen, who either forages for substrate or uses fecal fluids to manure the garden (depending on the species). The queen tends the new garden until the first brood of workers has been reared, at which point workers take over the tasks of tending the fungal cultivar and foraging for garden substrate. The colony continues to accumulate biomass of both ants and fungus until reaching sufficient size to produce new reproductive individuals. Colonies typically are perennial, living for many years and producing reproductives annually until the queen dies. Among the lower attines, colony and worker size are typically small, with no worker polymorphism. There is an apparent evolutionary trend toward greater colony and worker size as well as worker polymorphism from the lower to higher attines (34,91,93; Table 1). This trend finds its culmination in the leaf-cutter genus Atta, which can have colonies with millions of workers, can live for more than 10 years, and has strong worker polymorphism (87,88). FUNGI CULTIVATED BY FUNGUS-GROWING ANTS An understanding of this mutualism has been greatly hindered by the lack of information regarding the taxonomic placement and evolutionary history of the fungal cultivars. The traditional methods for fungal taxonomy and systematics depend on the morphology of fruiting structures; however, the fungi cultivated by attine ants do not readily produce these sexual structures in association with the ants or in pure culture (31,52,55). Although there generally has been a consensus that the fungi are basidiomycetes, likely in the order Agaricales (52,88), definitive generic identification was not possible prior to the recent development of molecular phylogenetic techniques. With the use of this technology, it has been established that most of the fungi belong to the family Lepiotaceae (Basidiomycota: Agaricales), in the tribe Leucocoprineae (16,32,56). This tribe is composed of two genera, Leucocoprinus and Leucoagaricus. Members of the Leucocoprineae are mostly topical species that are specialized litter decomposers (25,76). An extensive study by Mueller and colleagues (56) indicates that there are at least two distinct clades of leucocoprineous fungi that are cultivated by fungus-growing ants and, as I discuss below, the dynamics of the association between the ants and their fungi are complex. In contrast to most attines that cultivate fungi in the family Lepiotaceae, some ant species in the genus Apterostigma cultivate fungi in the family Tricholomataceae (16). These cultivars appear to be closely related to the wood decomposing fungi in the genus Gerronema (53). |
| 题型难度分析 | 这篇文章的难度比第一篇的难度要高一些，因为题型为选择题和两种配对题，而双配对题无疑很大程度上增加了这篇文章的难度。 |
| 题型技巧分析 | 配对题分类： 人/物体/地点/时间&特点/描述/事件 人名→理论 段落→具体信息 特点： 1）A: 当题目为专有名词、术语或物质名词时，题目一般遵循顺序原则 B: 当题目不是专有名词、术语或物质名词，而选项是时，题目不 遵循顺序原则 2）答案是否会重复使用？取决于NB 3）做题方法： A: 当题目为专有名词、术语或物质名词时，根据题目在原文定位，理 解原文对应内容并选出答案（着重考察对文章的理解） B: 当题目不是专有名词、术语或物质名词，而选项是时，在文章中把选项中所有的专有名词、术语或物质名词划出，然后在题目中划定位词在文章中定位。 注意：结构阅读法的运用 若某1、2题做不出来，可先做后面题目，然后再返回来做 |
| 剑桥雅思推荐原文练习 | 剑7Test 3 剑8Test 4 |
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