单选题
Grow Plants Without Water

    A. Ever since humanity began to farm our own food, we've faced the unpredictable rain that is both friend and enemy. It comes and goes without much warning, and a field of lush (茂盛的) leafy greens one year can dry up and blow away the next. Food security and fortunes depend on sufficient rain, and nowhere more so than in Africa, where 96% of farmland depends on rain instead of the irrigation common in more developed places. It has consequences: South Africa's ongoing drought—the worst in three decades—will cost at least a quarter of its corn crop this year.
    B. Biologist Jill Farrant of the University of Cape Town in South Africa says that nature has plenty of answers for people who want to grow crops in places with unpredictable rainfall. She is hard at work finding a way to take traits from rare wild plants that adapt to extreme dry weather and use them in food crops. As the earth's climate changes and rainfall becomes even less predictable in some places, those answers will grow even more valuable. 'The type of farming I'm aiming for is literally so that people can survive as it's going to get more and more dry,' Farrant says.
    C. Extreme conditions produce extremely tough plants. In the rusty red deserts of South Africa, steep-sided rocky hills called inselbergs rear up from the plains like the bones of the earth. The hills are remnants of an earlier geological era, scraped bare of most soil and exposed to the elements. Yet on these and similar formations in deserts around the world, a few fierce plants have adapted to endure under ever-changing conditions.
    D. Farrant calls them resurrection plants (复苏植物). During months without water under a harsh sun, they wither, shrink and contract until they look like a pile of dead gray leaves. But rainfall can revive them in a matter of hours. Her time-lapse (间歇性拍摄的) videos of the revivals look like someone playing a tape of the plant's death in reverse.
    E. The big difference between 'drought-tolerant' plants and these tough plants: metabolism. Many different kinds of plants have developed tactics to weather dry spells. Some plants store reserves of water to see them through a drought; others send roots deep down to subsurface water supplies. But once these plants use up their stored reserve or tap out the underground supply, they cease growing and start to die. They may be able to handle a drought of some length, and many people use the term 'drought tolerant' to describe such plants, but they never actually stop needing to consume water, so Farrant prefers to call them drought resistant.
    F. Resurrection plants, defined as those capable of recovering from holding less than 0.1 grams of water per gram of dry mass, are different. They lack water-storing structures, and their existence on rock faces prevents them from tapping groundwater, so they have instead developed the ability to change their metabolism. When they detect an extended dry period, they divert their metabolisms, producing sugars and certain stress-associated proteins and other materials in their tissues. As the plant dries, these resources take on first the properties of honey, then rubber, and finally enter a glass-like state that is 'the most stable state that the plant can maintain,' Farrant says. That slows the plant's metabolism and protects its dried-out tissues. The plants also change shape, shrinking to minimize the surface area through which their remaining water might evaporate. They can recover from months and years without water, depending on the species.
    G. What else can do this dry-out-and-revive trick? Seeds—almost all of them. At the start of her career, Farrant studied 'recalcitrant seeds (顽拗性种子),' such as avocados, coffee and lychee. While tasty, such seeds are delicate—they cannot bud and grow if they dry out (as you may know if you've ever tried to grow a tree from an avocado pit). In the seed world, that makes them rare, because most seeds from flowering plants are quite robust. Most seeds can wait out the dry, unwelcoming seasons until conditions are right and they sprout (发芽). Yet once they start growing, such plants seem not to retain the ability to hit the pause button on metabolism in their stems or leaves.
    H. After completing her Ph.D. on seeds, Farrant began investigating whether it might be possible to isolate the properties that make most seeds so resilient (迅速恢复活力的) and transfer them to other plant tissues. What Farrant and others have found over the past two decades is that there are many genes involved in resurrection plants' response to dryness. Many of them are the same that regulate how seeds become dryness-tolerant while still attached to their parent plants. Now they are trying to figure out what molecular signaling processes activate those seed-building genes in resurrection plants—and how to reproduce them in crops. 'Most genes are regulated by a master set of genes,' Farrant says. 'We're looking at gene promoters and what would be their master switch.'
    I. Once Farrant and her colleagues feel they have a better sense of which switches to throw, they will have to find the best way to do so in useful crops. 'I'm trying three methods of breeding,' Farrant says: conventional, genetic modification and gene editing. She says she is aware that plenty of people do not want to eat genetically modified crops, but she is pushing ahead with every available tool until one works. Farmers and consumers alike can choose whether or not to use whichever version prevails: 'I'm giving people an option.'
    J. Farrant and others in the resurrection business got together last year to discuss the best species of resurrection plant to use as a lab model. Just like medical researchers use rats to test ideas for human medical treatments, botanists use plants that are relatively easy to grow in a lab or greenhouse setting to test their ideas for related species. The Queensland rock violet is one of the best studied resurrection plants so far, with a draft genome (基因图谱) published last year by a Chinese team. Also last year, Farrant and colleagues published a detailed molecular study of another candidate, Xerophyta viscosa, a tough-as-nail South African plant with lily-like flowers, and she says that a genome is on the way. One or both of these models will help researchers test their ideas—so far mostly done in the lab—on test plots.
    K. Understanding the basic science first is key. There are good reasons why crop plants do not use dryness defenses already. For instance, there's a high energy cost in switching from a regular metabolism to an almost-no-water metabolism. It will also be necessary to understand what sort of yield farmers might expect and to establish the plant's safety. 'The yield is never going to be high,' Farrant says, so these plants will be targeted not at Iowa farmers trying to squeeze more cash out of high-yield fields, but subsistence farmers who need help to survive a drought like the present one in South Africa. 'My vision is for the subsistence farmer,' Farrant says. 'I'm targeting crops that are of African value.'
问答题     There are a couple of plants tough and adaptable enough to survive on bare rocky hills and in deserts.
 
【正确答案】C
【答案解析】注意抓住题干中的关键信息a couple of和adaptable enough to survive on bare rocky hills and in deserts。文章段落中论及有少量植物具备足够的适应能力,可以在光秃秃的岩石山和沙漠中生存的内容出现在C段。该段最后一句指出,在世界各地沙漠中的这些山丘和类似的地形中,有少量顽强的植物已经适应环境,能够在不断变化的气候条件下存活。可见,题干是对原文的同义转述。题干中的a couple of对应原文中的a few;题干中的on bare rocky hills and in deserts对应原文中的on these and similar formations in deserts,该处的these指代的是上文中提到的steep-sided rocky hills。
问答题     Farrant is trying to isolate genes in resurrection plants and reproduce them in crops.
 
【正确答案】H
【答案解析】注意抓住题干中的关键信息isolate genes in resurrection plants and reproduce them in crops。文章段落中论及法兰特分离复活植物中的基因并将其复制到农作物中的内容出现在H段。该段首句指出,在法兰特完成攻读种子专业的博士学位之后,她开始调查是否能够将那些使大多数种子迅速恢复活力的特性分离出来,并将它们转换到其他植物组织中。随后在该段第四句中提到,现在,法兰特和其他一些人正试图弄清楚是什么分子信号传导过程激活了复活植物中的那些构建种子的基因——以及如何将它们复制到农作物中。可见,题干是对原文的同义转述。题干中的isolate和reproduce them in crops属于原词重现。
问答题     Farmers in South Africa are more at the mercy of nature, especially inconsistent rainfall.
 
【正确答案】A
【答案解析】注意抓住题干中的关键信息farmers in South Africa和more at the mercy of nature。文章段落中论及南非的农民更多地受制于自然的内容出现在A段。该段第三句指出,食物的安全和命运有赖于充足的雨水,非洲尤其如此,在那里,96%的农田都依靠雨水,而不是更发达的地方常见的灌溉。可见,题干是对原文的同义转述。题干中的at the mercy of nature,especially inconsistent rainfall对应原文中depend on sufficient rain,其中at the mercy of为固定用法,意为“受……支配”;题干中的farmers in South Africa are more对应原文中的nowhere more so than in Africa。
问答题     Resurrection crops are most likely to be the choice of subsistence farmers.
 
【正确答案】K
【答案解析】注意抓住题干中的关键信息resurrection crops和the choice of subsistence farmers。文章段落中论及复活作物最有可能成为仅能维持生存的农民的选择的内容出现在K段。该段第五句引用了法兰特的原话,提到“产量永远都不会高,因此这些植物所面向的人群不是那些试图从高产量的土地上榨取更多现金的爱荷华州的农民,而是那些仅能维持生存、需要帮助以成功渡过类似当下南非所处的旱情的农民。”可见,题干是对原文的同义转述。题干中的most likely to be the choice of subsistence farmers对应原文中的will be targeted...subsistence farmers。
问答题     Even though many plants have developed various tactics to cope with dry weather, they cannot survive a prolonged drought.
 
【正确答案】E
【答案解析】注意抓住题干中的关键信息many plants have developed various tactics to cope with dry weather。文章段落中论及很多植物具备了各种应对干旱天气的技能的内容出现在E段。该段第二句指出,很多不同种类的植物已经掌握了平安度过干旱期的技能。随后又进一步说到一旦这些植物将它们储备的水源用完了,或者是将地下水源利用殆尽,它们就会停止生长,并开始走向死亡。它们可能可以应付一段时间的干旱,但是事实上它们对于消耗水源的需求从来都没有停止过。可见,题干是对原文的同义概述。题干中的to cope with dry weather对应原文中的to weather dry spells。注意,原文中用到weather作动词,意为“经受住”;题干中的tactics属于原词重现。
问答题     Despite consumer resistance, researchers are pushing ahead with genetic modification of crops.
 
【正确答案】I
【答案解析】注意抓住题干中的关键信息consumer resistance和pushing ahead with genetic modification of crops。文章段落中论及消费者抵制转基因食品和研究人员推进转基因作物的研究的内容出现在I段。该段第三句指出,法兰特说她知道很多人不想食用转基因粮食,但是她还是在运用所有可用的工具加以推进,直至有一种方法奏效。可见,题干是对原文的同义转述。题干中的consumer resistance对应原文中people do not want to eat;题干中的pushing ahead属于原词重现。
问答题     Most seeds can pull through dry spells and begin growing when conditions are ripe, but once this process starts, it cannot be held back.
 
【正确答案】G
【答案解析】注意抓住题干中的关键信息most seeds和begin growing when conditions are ripe。文章段落中论及大多数种子会等到条件成熟再开始生长的内容出现在G段。该段最后两句指出,大多数种子都能够等待不受欢迎的干旱季节过去,直到气候条件变得合适再发芽。但是这类植物一旦开始生长,似乎就无法维持其根茎或叶子新陈代谢暂停的能力了。可见,题干是对原文的同义转述。题干中的pull through对应原文中的wait out;题干中的begin growing when conditions are ripe对应原文中的until conditions are right and they sprout;题干中的held back意为“阻止;克制”,对应原文中的hit the pause button。
问答题     Farrant is working hard to cultivate food crops that can survive extreme dryness by studying the traits of rare wild plants.
 
【正确答案】B
【答案解析】注意抓住题干中的关键信息working hard和studying the traits of rare wild plants。文章段落中论及法兰特努力研究野生植物特性的内容出现在B段。该段第二句指出,她(法兰特)正在努力寻找一种办法,从那些能够适应极端干燥天气的稀有野生植物中提取特性,并将它们用于粮食作物。可见,题干是对原文的同义转述。题干中的is working hard to对应原文中的is hard at work;题干中的survive extreme dryness对应原文中的adapt to extreme dry weather;题干中的studying the traits of对应原文中的take traits from。
问答题     By adjusting their metabolism, resurrection plants can recover from an extended period of drought.
 
【正确答案】F
【答案解析】注意抓住题干中的关键信息adjusting their metabolism和recover from an extended period of drought。文章段落中论及复活植物调整其新陈代谢机制以能够经受住长时间干旱的内容出现在F段。该段第三句指出,当它们(复活植物)探测到会有一个较长的干旱期时,它们会转换自己的新陈代谢机制,在它们的组织中产生糖分和某些与压力相关的蛋白质,以及其他一些物质。可见,题干是对原文的同义转述。题干中的adjusting对应原文中的divert;题干中的an extended period of drought对应原文中的an extended dry period。
问答题     Resurrection plants can come back to life in a short time after a rainfall.
 
【正确答案】D
【答案解析】注意抓住题干中的关键信息come back to life in a short time after a rainfall。文章段落中论及复活植物在降雨之后很短的时间内恢复活力的内容出现在D段。该段第二句和第三句指出,在烈日当空、没有水的几个月里,复活植物枯萎、收缩,直至看上去就像是一堆枯死的灰色的叶子。但是降水可以使它们在几个小时左右的时间内恢复活力。由此可见,题干是对原文的同义转述。题干中的come back to life对应原文中的revive;题干中的rainfall属于原词重现。