雅思OGtest7阅读第二篇文章第一题正确答案为(the) hairs ，解题关键词为leaf
，关键句为A段第1句和第2句前半句，具体的解题思路详见雅思OGtest7阅读passage2原文题目及答案解析【附译文】正文介绍。
Fatal Attraction
Evolutionist Charles Darwin first marvelled at flesh-eating plants in the mid-19th century .Today, biologists, using 21st-century tools to study cells and DNA, are beginning to understand how these plants hunt, eat and digest - and how such bizarre adaptations arose in the first place.
A
The leaves of the Venus flytrap plant are covered in hairs. When an insect brushes against them, this triggers a tiny electric charge, which travels down tunnels in the leaf and opens up pores in the leaf’s cell membranes. Water surges from the cells on the inside of the leaf to those on the outside, causing the leaf to rapidly flip in shape from convex to concave, like a soft contact lens. As the leaves flip, they snap together, trapping the insect in their sharp-toothed jaws.
B
The bladderwort has an equally sophisticated way of setting its underwater trap.
It pumps water out of tiny bag-like bladders, making a vacuum inside. When small creatures swim past, they bend the hairs on the bladder, causing a flap to open. The low pressure sucks water in, carrying the animal along with it. In one five-hundredth of a second, the door swings shut again. The Drosera sundew, meanwhile, has a thick, sweet liquid oozing from its leaves, which first attracts insects, then holds them fast before the leaves snap shut. Pitcher plants use yet another strategy, growing long tube-shaped leaves to imprison their prey. Raffles' pitcher plant, from the jungles of Borneo, produces nectar that both lures insects and forms a slick surface on which they can't get a grip. Insects that land on the rim of the pitcher slide on the liquid and tumble in.
C
Many carnivorous plants secrete enzymes to penetrate the hard exoskeleton of insects so they can absorb nutrients from inside their prey. But the purple pitcher plant, which lives in bogs and infertile sandy soils in North America, enlists other organisms to process its food. It is home to an intricate food web of mosquito larvae, midges and bacteria, many of which can survive only in this unique habitat. These animals shred the prey that fall into the pitcher, and the smaller organisms feed on the debris. Finally, the plant absorbs the nutrients released.
D
While such plants clearly thrive on being carnivorous, the benefits of eating flesh are not the ones you might expect. Carnivorous animals such as ourselves use the carbon in protein and the fat in meat to build muscles and store energy. Carnivorous plants instead draw nitrogen, phosphorus, and other critical nutrients from their prey in order to build light-harvesting enzymes. Eating animals, in other words, lets carnivorous plants do what all plants do: carry out photosynthesis, that is, grow by harnessing energy directly from the sun.
E
Carnivorous plants are, in fact, very inefficient at converting sunlight into tissue. This is because of all the energy they expend to make the equipment to catch animals - the enzymes, the pumps, and so on. A pitcher or a flytrap cannot carry out much photosynthesis because, unlike plants with ordinary leaves, they do not have flat solar panels that can grab lots of sunlight. There are, however, some special conditions in which the benefits of being carnivorous do outweigh the costs. The poor soil of bogs, for example, offers little nitrogen and phosphorus, so carnivorous plants enjoy an advantage over plants that obtain these nutrients by more conventional means. Bogs are also flooded with sunshine, so even an inefficient carnivorous plant can photosynthesise enough light to survive.
F
Evolution has repeatedly made this trade-off. By comparing the DNA of carnivorous plants with other species, scientists have found that they evolved independently on at least six separate occasions. Some carnivorous plants that look nearly identical turn out to be only distantly related. The two kinds of pitcher plants - the tropical genus Nepenthes and the North American Sarracenia - have, surprisingly, evolved from different ancestors, although both grow deep pitcher- shaped leaves and employ the same strategy for capturing prey.
G
In several cases, scientists can see how complex carnivorous plants evolved from simpler ones. Venus flytraps, for example, share an ancestor with Portuguese sundews, which only catch prey passively, via 'flypaper' glands on their stems. They share a more recent ancestor with Drosera sundews, which can also curl their leaves over their prey. Venus flytraps appear to have evolved an even more elaborate version of this kind of trap, complete with jaw-like leaves.
H
Unfortunately, the adaptations that enable carnivorous plants to thrive in marginal habitats also make them exquisitely sensitive. Agricultural run-off and pollution from power plants are adding extra nitrogen to many bogs in North America. Carnivorous plants are so finely tuned to low levels of nitrogen that this extra fertilizer is overloading their systems, and they eventually burn themselves out and die.
I
Humans also threaten carnivorous plants in other ways. The black market trade in exotic carnivorous plants is so vigorous now that botanists are keeping the location of some rare species a secret. But even if the poaching of carnivorous plants can be halted, they will continue to suffer from other assaults. In the pine savannah of North Carolina, the increasing suppression of fires is allowing other plants to grow too quickly and outcompete the flytraps in their native environment. Good news, perhaps, for flies. But a loss for all who, like Darwin, delight in the sheer inventiveness of evolution.
Questions 14-18
Complete the notes below.
Choose NO MORE THAN TWO WORDS from the passage for each answer. Write your answers in boxes 14-18 on your answer sheet.
How a Venus flytrap traps an insect
insect touches 14__________ on leaf of plant
small 15__________ passes through leaf
16__________ in cell membrane open
outside cells of leaves fill with 17__________
leaves change so that they have a 18__________ shape and snap shut
Questions 19-22
Look at the following statements (Questions 19-22) and the list of plants. Match each statement with the correct plant, A, B, C, D or E.
Write the correct letter, A, B, C, D or E, in boxes 19-22 on your answer sheet.
19 It uses other creatures to help it digest insects.
20 It produces a slippery substance to make insects fall inside it.
21 It creates an empty space into which insects are sucked.
22 It produces a sticky substance which traps insects on its surface.
List of plants
A Venus flytrap
B bladderwort
C Drosera sundew
D Raffles’ pitcher plant
E purple pitcher plant
Questions 23-26
Reading Passage 2 has nine paragraphs, A—I
Which paragraph contains the following information?
Write the correct letter, A-l, in boxes 23-26 on your answer sheet
23 a mention of a disadvantage of the leaf shape of some carnivorous plants
24 an example of an effort made to protect carnivorous plants
25 unexpected information about the origins of certain carnivorous plants
26 an example of environmental changes that shorten the life cycles of carnivorous plants
Question 14
答案：(the) hairs
关键词：leaf
定位原文：A段第1句和第2句前半句“The leaves of the Venus flytrap plant are covered in hairs. When an insect brushes against them…”
解题思路：题目关键词是leaf，定位到A段第1句和第2句前半句，“捕蝇草植物的叶子是被毛发包住的。当昆虫触碰它们的时候…”。题目句的touches是对brushes against的同义改写，所以正确答案是“hairs”。
Question 15-16
答案：
15 (electric) charge
16 pores
关键词：membrane
定位原文：A段第2句“When an insect brushes against them, this triggers a tiny electric charge, which travels down tunnels in the leaf and opens up pores in the leaf’s cell membranes.”
解题思路：题目关键词是membrane，继续定位到A段第2句，“当昆虫触碰它们的时候，就触发了一个小的电荷，这个小电荷就从叶子里的通道通过，并且使叶子细胞膜的孔张开”。15题题目句的small是对tiny的同义改写， passes through leaf是对travel down tunnels in leaf的同义改写。tunnel，隧道，通道;pore，毛孔，气孔，细孔;membrane，(动物或植物体内的)薄膜。
Question 17-18
答案：
17 water
18 concave
关键词：outside/snap shut
定位原文：A段第3-4句“Water surges from the cells on the inside of the leaf to those on the outside, causing the leaf to rapidly flip in shape from convex to concave, like a soft contact lens. As the leaves flip, they snap together…”
解题思路：根据关键词继续定位到A段第3-4句。“水从叶子内的细胞涌到叶子外的细胞，造成了叶片迅速翻转，形状从凸到凹，好像一个柔软的隐形眼镜片一样。树叶的翻转时候，会‘啪’一下儿合上”。18题题目句中的from…to…是对定位句中的change的同义改写。surge在文中的意思是“汹涌，涌出”;flip在文中的意思是“翻转”;convex，凸的，凸形;concave，凹的，凹形;contact lens，隐形眼镜。
Question 19
答案：E
关键词：purple pitcher plant
定位原文：C段倒数第2句“But the purple pitcher plant, which lives in bogs and infertile sandy soils in North America, enlists other organisms to process its food.”
解题思路：做此类型的题目最好的方法是利用选项中的词作关键词去文中定位，然后根据题干做匹配。利用关键词purple pitcher plant定位到C段倒数第2句时，“但是紫色猪笼草，在美国北部的沼泽和贫瘠的沙质土壤中生活，获得其他生物体的帮助来加工食物”。我们发现19题题干句是对定位句的同义改写，digest insects是对process food的同义改写，故19题选E。
Question 20
答案：D
关键词：Raffles’ pitcher plant
定位原文：B段最后两句“… produces nectar that both lures insects and forms a slick surface on which they can't get a grip. Insects that land on the rim of the pitcher slide on the liquid and tumble in.”
解题思路：利用关键词Raffles’ pitcher plant定位到B段倒数第2句，它的捕食方式定位到这句和段尾句。“产生花蜜，吸引昆虫，形成一个光滑的表面，让昆虫站不住。落在叶子边缘的昆虫就顺着液体滑进去”。对照题干，第20句“它产生滑溜的物质，让昆虫摔进去”是对定位句的同义改写，故20题选D。
Question 21
答案：B
关键词：bladderwort
定位原文：B段第2-4句“It pumps water out of tiny bag-like bladders, making a vacuum inside… The low pressure sucks water in, carrying the animal along with it”
解题思路：根据选项中的“bladderwort”定位到B段该部分，“它把水从微小的袋状囊排出，使里面成为真空。当小动物游过去，他们将囊状物上毛发弯曲，导致皮瓣打开。低压把水吸入，同时也把昆虫带进去”。对照题干，此题题干是对定位句的同义改写。empty space是对vacuum的同义改写，故这题选B。
Question 22
答案：C
关键词：Drosera sundew
定位原文：B段第6句“… has a thick, sweet liquid oozing from its leaves, which first attracts insects, then holds them fast before the leaves snap shut.”
解题思路：在利用关键词Drosera sundew定位的过程中，我们发现它的捕食方式正好在B段第6句。“它有一个厚厚的，甜的液体渗出叶子，这种液体先吸引昆虫，在叶子合上之前牢牢地抓住它们”，22题题干正好是对这句话的同义改写。holds them fast是对traps insects in its surface的同义改写，故22题选C。
Question 23
答案：E
关键词：disadvantage of the leaf
定位原文：E段第3句“A pitcher or a flytrap cannot carry out much photosynthesis because, unlike plants with ordinary leaves, they do not have flat solar panels that can grab lots of sunlight.”
解题思路：利用关键词结合速读各段1-3句的方法，定位到E段第3句，“猪笼草或捕蝇器不能进行很多光合作用，因为和普通植物的叶子不一样，它们没有能接受太阳能的平台，来吸收很多阳光”。题目句子就是对这句话的同义改写，some carnivorous plants指的就是a pitcher or a flytrap，disadvantage of the leaf指的就是这些植物的叶子形状与普通植物的叶子不一样。
Question 24
答案：I
关键词：protect
定位原文：I段第2句“The black market trade in exotic carnivorous plants is so vigorous now that botanists are keeping the location of some rare species a secret.”
解题思路：利用关键词结合速读各段1-3句的方法，定位到I段第2句，“奇异食肉植物的黑市交易非常活跃，以至于现在的植物学家不得不对稀有物种的种植地点保密”。an effort to protect carnivorous plants指的就是科学家对于种植地进行保密的事。
Question 25
答案：F
关键词：unexpected information/origins
定位原文：F段第2-3句“By comparing the DNA of carnivorous plants with other species, scientists have found that they evolved independently on at least six separate occasions. Some carnivorous plants that look nearly identical turn out to be only distantly related.”
解题思路：利用关键词结合速读各段1-3句的方法，定位到F段第2-3句，“通过将食肉植物的基因与其他物种的基因进行比较，科学家们发现，他们在至少六个不同的场合完成了进化。一些外形基本相同的食肉植物仅仅是远亲而已”。题目句中的origins是对DNA的同义改写，unexpected information是对第3句话内容的概括。
Question 26
答案：H
关键词：environmental changes/shorten life cycles
定位原文：H段第2-3句“Agricultural run-off and pollution from … burn themselves out and die”
解题思路：利用关键词结合速读各段1-3句的方法，定位到H段第2句和第3句，“农业径流和来自发电厂的污染，使美国北部很多沼泽地增加了额外的氮。过多的氮肥，造成了特别适应低氮水平的食肉植物的自身含氮量超载，最终耗尽自己并死亡”。题目句子是对定位句的同义改写，environmental changes是对Agricultural run-off and pollution from power plants的概括描述，shorten life cycles是对第3句话的大意概括。