朗阁雅思 > 雅思考题回顾

2022年8月11日:雅思阅读题目回顾

时间:2022-08-18 18:17来源:江苏朗阁外语培训中心 作者:jasmine

  P1 植物气味

  P2 通过研究以前的航海日志研究气候变化

  P3 尝试破译一本古代的手稿(Voynich Manuscript)

  朗阁讲师王晓莲点评

  1. 本场考试的难度较难。

  2. 整体分析:涉及植物类(P1)、环境类(P2)、社科类(P3)。

  本次考试话题较为晦涩,理解难度大。**篇文章抛弃了传统的填空题+单选题题型搭配,在**篇就考察了配对题+判断题+选择题题型。考生普遍反应三篇文章阅读耗时长,定位困难,读不懂文章。考生在平时复习时一定夯实基础,积累生词和替换词,提升长难句理解能力,从根本上提升阅读实力。

  3. 部分答案及参考文章:

  Passage 1:植物气味

  题型:配对题+判断题+选择题

  A

  Everyone is familiar with scented flowers, and many people have heard that floral odors help the plant attract pollinators. This common notion is mostly correct, but it is surprising how little scientific proof of it exists. Of course, not all flowers are pollinated by biological agents – for example, many grasses are wind-pollinated – but the flowers of the grasses may still emit volatiles. In fact, plants emit organic molecules all the time, although they may not be obvious to the human nose. As for flower scents that we can detect with our noses, bouquets that attract moths and butterflies generally smell “sweet,” and those that attract certain flies seem “rotten” to us.

  B

  The release of volatiles from vegetative parts of the plant is familiar, although until recently the physiological functions of these chemicals were less clear and had received much less attention from scientists. When the trunk of a pine tree is injured – for example, when a beetle tries to burrow into it – it exudes a very smelly resin. This resin consists mostly of terpenes – hydrocarbons with a backbone of 10, 15 or 20 carbons that may also contain atoms of oxygen. The heavier C20 terpenes, called diterpenes, are glue-like and can cover and immobilize insects as they plug the hole. This defense mechanism is as ancient as it is effective: Many samples of fossilized resin, or amber, contain the remains of insects trapped inside. Many other plants emit volatiles when injured, and in some case, the emitted signal helps defend the plant. For example, (Z)-3-hexenyl acetate, which is known as a “green leaf volatile” because it is emitted by many plants upon injury, deters females of the moth Heliothis virescens from laying eggs on injured tobacco plants. Interestingly, the profile of emitted tobacco volatiles is different at night than during the day, and it is the nocturnal blend, rich in several (Z)-3-hexen-1-olesters, that is most effective in repelling the night-active H. virescens moths.

  C

  Herbivore induced volatiles often serve as indirect defenses. These bulwarks exist in a variety of plant species, including corn, beans, and the model plant species Arabidopsis thaliana. Plants not only emit volatiles acutely, at the site where caterpillars, mites, aphids or similar insects are eating them but also generally from non-damaged parts of the plant. These signals attract a variety of predatory insects that prey on the plant-eaters. For example, some parasitic wasps can detect the volatile signature of a damaged plant and will lay their eggs inside the offending caterpillar; eventually, the wasp eggs hatch, and the emerging larvae feed on the caterpillar from the inside hatch, and the emerging larvae feed on the caterpillar from the inside out. The growth of infected caterpillars is retarded considerably, to the benefit of the plant. Similarly, volatiles released by plants in response to herbivore egg laying can attract parasites of the eggs, thereby preventing them from hatching and avoiding the onslaught of hungry herbivores that would have emerged. Plant volatiles can also be used as a kind of currency in some very indirect defensive schemes. In the rainforest understory tree Leonardoxa Africana, ants of the species Petalomyrmex phylax patrol young leaves and attack any herbivorous insects that they encounter. The young leaves emit high levels of the volatile compound methyl salicylate, a compound that the ants use either as a pheromone or as an antiseptic in their nests. It appears that methyl salicylate is both an attractant and a reward offered by the tree to get the ants to perform this valuable deterrent role.

  D

  Floral scent has a strong impact on the economic success of many agricultural crops that rely on insect pollinators, including fruit trees such as the bee-pollinated cherry, apple, apricot and peach, as well as vegetables and tropical plants such as papaya. Pollination not only affects crop yield, but also the quality and efficiency of crop production. Many crops require most, if not all, ovules to be fertilized for optimum fruit size and shape. A decrease in fragrance emission reduces the ability of flowers to attract pollinators and results in considerable losses for growers, particularly for introduced species that had a specialized pollinator in their place of origin. This problem has been exacerbated by recent disease epidemics that have killed many honeybees, the major insect pollinators in the United States.

  E

  One means by which plant breeders circumvent the pollination problem is by breeding self-compatible, or apomictic, varieties that do not require fertilization. Although this solution is adequate, its drawbacks include near genetic uniformity and consequent susceptibility to pathogens. Some growers have attempted to enhance honeybee foraging by spraying scent compounds on orchard trees, but this approach was costly, had to be repeated, had potentially toxic effects on the soil or local biota, and, in the end, proved to be inefficient. The poor effectiveness of this strategy probably reflects inherent limitations of the artificial, topically applied compounds, which clearly fail to convey the appropriate message to the bees. For example, general spraying of the volatile mixture cannot tell the insects where exactly the blossoms are. Clearly, a more refined strategy is needed. The ability to enhance existing floral scent, which could all be accomplished by genetic engineering, would allow us to manipulate the types of insect pollinators and the frequency of their visits. Moreover, the metabolic engineering of fragrance could increase crop protection against pathogens and pests.

  F

  Genetic manipulation of the scent will also benefit the floriculture industry. Ornamentals, including cut flowers, foliage and potted plants, play an important aesthetic role in human life. Unfortunately, traditional breeding has often produced cultivars with improved vase life, shipping characteristics, color and shape while sacrificing desirable perfumes. The loss of scent among ornamentals, which have a worldwide value of more than $30 billion, makes them important targets for the genetic manipulation of flower fragrance. Some work has already begun in this area, as several groups have created petunia and carnation plants that express the linalool synthase gene from C. Breweri. These experiments are still preliminary: For technical reasons, the gene was expressed everywhere in the plant, and although the transgenic plants did create small amounts of linalool, the level was below the threshold of detection for the human nose. Similar experiments in tobacco used genes for other monoterpene synthases, such as the one that produces limonene, but gave similar results.

  G

  The next generation of experiments, already in progress, includes sophisticated schemes that target the expression of scent genes specifically to flowers or other organs – such as special glands that can store antimicrobial or herbivore – repellent compounds.

  参考答案

  1.B

  2.A

  3.F

  4.C

  5.TRUE

  6.NOT GIVEN

  7.TRUE

  8.FALSE

  9.B

  10.B

  11.C

  12.D

  13.A

  Passage 2:通过研究以前的航海日志研究气候变化

  具体文章题型和参考答案待确认

  Passage 3:尝试破译一本古代的手稿

  具体文章题型和参考答案待确认

  考试建议

  1.从已知信息来看,阅读速度依旧是影响考生得分的关键。同时,***近考试常常考察选择题型,该题型相对来说对细节要求更高,耗时更长。如果平时烤鸭没有太关注选择题的话,可以参考练习10-4-3,11-2-3,11-4-2,12-3-3,12-4-2,13-1-3。下场考试,烤鸭们还是注意首篇出现填空+判断的篇章。第二篇注意出现配对题相关的搭配。课下练习注意时间分配合理,熟练掌握各个题型和篇章搭配类型的定位方法。同时,下场考试注意List of Headings题型可能会出现,重点注意常见段落结构如何区分主次信息,抽象选项和原文信息如何识别出对应点。填空题除了高频直接填空外,还需关注选词填空。

  3. 重点浏览2016到2021年机经。



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