【雅思备考】今日练习题-Reading,环球雅思墨尔本分校微信公众号文章

为了帮助同学们更好的学习，

我们环球墨尔本分校，

特别推出雅思每日练习啦~

供小伙伴们练习，

还不快跟着我们的步伐学起来备考起来！

让我们一起早日征服雅思！

【雅思备考】今日练习题 - Reading

READING PASSAGE 1

You should spend about 20minutes on Questions 1-13 which are based on Reading Passage 1 below.

Going Bananas

The world's favourite fruit could disappear forever in 10 years' time.

A. The banana is among the world's oldest crops. Agricultural scientists believe that the first edible banana was discovered around ten thousand years ago. It has been at lan evolutionary standstill ever since it was first propagated in the jungle of South East Asia at the end of the last ice age. Normally the wild banana, a giant jungle herb called Musa acuminata, contains a mass of hard seeds that make the fruit virtually inedible. But now and then, hunter-gatherers must have discovered rare mutant plants that produced seedless, edible fruits. Geneticists now know that the vast majority of these soft-fruited plants resulted from genetic accidents that gave their cells three copies o feach chromosome instead of the usual two. This imbalance prevents seeds and pollen from developing normally, rendering the mutant plants sterile. And that is why some scientists believe the world's most popular fruit could be doomed. It lacks the genetic diversity to fight off pests and diseases that are invading the banana plantations of Central America and the small holdings of Africa and Asia alike.

B. In some ways, the banana today resembles the potato before blight brought famineto Ireland a century and a half ago. But it holds a lesson for other crops too, says Emile Frison, top banana at the International Network for the Improvement of Banana and Plantain in Montpellier, France. The state of the banana, Frison Warnsy can teach a broader lesson: the increasing standardisation of food crops round the world is threatening their ability to adapt and survive.

C. The first Stone Age plant breeders cultivated these sterile freaks by replanting cuttings from their stems. And the descendants of those original cuttings are the bananas we still eat today. Each is a virtual clone, almost devoid of genetic diversity. And that conformity makes it ripe for disease like no other crop on Earth. Traditional varieties of sexually reproducing crops have always had a much broader genetic base, and the genes will recombine in new arrangements in each generation. Uhls gives them much greater flexibility in evolving responses to disease 一 decrease the genetic resources to draw on in the face of an attack. But that advantage is fading fast as growers increasingly plant the same few, high-yielding varieties. Plant breeders work feverishly to maintain resistance in these standardised cjopa.Should efforts falter, yields of even the most productive crop could swiftly crash. "When some pest or disease comes along, seveye epidemics can occur, says Geoff Hawtiiv director of the Rome-based International Plant Genetic Resources Institute.

D. The banana is an excellen tcase in point. Until the 1950s, one variety, the Gros Michel, dominated the world's commercial banana business. Found by French botanists in Asia in the1820s, the Gros Michel by all accounts a fine banana, richer and sweeter than today's standard banana and without the latter bitter after taste when green. But it was vulnerable to a soil fungus that produced a wilt known as Panama disease."Once the fungus get into the soil, it remains there for many years. There is nothing farmers can do. Even chemical spraying won't get rid of it, says Rodomiro Ortiz, director of the International Institute for Tropical Agriculturein Ibadan, Nigeria. So plantation owners played a running game, abandoning infested fields and moving to "clean" land — until they ran out of clean land in the 1950s and had to abandon the Gros Michel. Its successor, and still the reigning commercial king, is the Cavendish banana, a 19th-century British discovery from southern China. The Cavendish is resistant to Panama disease and, as a result, it literally saved the international banana industry. During the 1960s, it replaced the Gros Michel on supermarket shelves. If you buy a banana today, it is almost certainly a Cavendish. But even so, it is aminority in the world's banana crop.

E. Half a billion people in Asia and Africa depend on bananas. Bananas provide the largest source of calories and are eaten daily. Its name is synonymous with food. But the day of reckoning may be coming for the Cavendish and its indigenous kin. Another fungal disease, black Sigatoka, has become a global epidemic since its first appearance in Fijiin 1963. Left to itself, black Sigatoka — which causes brown wounds on leave sand premature fruit ripening — cuts fruit yields by 50 to 70 per cent and reduces the productive lifetime of banana plants from 30 years to as little as 2 or 3. Commercial growers keep Sigatoka at bay by a massive chemical assault. Forty sprayings of fungicide a year is typical. But even so, diseases such as black Sigatoka are getting more and more difficult to control. "As soon as you bring in a new fungicide, they develop resistance, says Frison. " One thing we can be sure of is that the Sigatoka won't lose in this battle." Poor farmers, who cannot afford chemicals, have it even worse. They can do little more than watch their plants die, "Most of the banana fields in Amazonia have already been destroyed by the disease," says Luadir Gasparotto, Brazil's leading banana pathologist with the government agency EMBRAPA. Production is likely to fall by 70 per cent as the disease spreads, he predicts. The only option will be to find a new variety,

F. But how? Almost all edible varieties are susceptible to the disease go, gypw, erscannot simply change to a different banana. With most crops, such a threat would unleash an army, of breeder scopriag the orld for resistant relatives whose traits Key dan Irced Varieties, Not so with thebanana. Becaxie all edible varieties are sterile, bringing in new genetictraife to help cope with pests and diseases is nearly impossible. Nearly, but not totally. Very rarely, a sterile banana will experience a genetic accidentthat allows almost normal seed to develop, giving breeders a tiny windowfor improvement. Breeders at the Honduran Foundatiort of Agricultural Researchhave tried to exploit this to create disease-resistant varieties. Further backcrossing with wild bananas yielded a new seedles banana resistant to both black Sigatoka and Panama disease.

G. Neither Western supermarket consume nor peasant growers like the new hybrid. Some accuse it of tasting more like an apple than a banana. Not surprisingly, the majority of plant breeders have until now turned their backs on the banana and got to work on easier plants. And commercial banana companies are now washing their hands of the whole breeding effort, preferring to find and search for new fungicides instead. "We supported a brceding programme for 40 years, but it wasn't able to develop an alternative to Cavendish. It was very expensive and we got nothing back." says Ronald Romero, head of research at Chicjuita, one of the Big Three companies that dominate the international banana trade.

H. Last year, a global consortium of scientists led by Frison announced plans to sequence the banana genome within five years. It would be the first edible fruit to be sequenced. Well, almost edible. The group will actually be sequencing inedible wild bananas from East Asia cause many of these are resistant to black Sigatoka. If they can pinpoint the genes that help these wild varieties to resist black Sigatoka, the protective genes could be introduced into laboratory tissue cultures of cells from edible varieties.These could then be propagated into new, resistant plants and passed on to farmers.

I. It sounds promising, but the big banana companies have, until now, refused to get involved in GM research for fear of alienating their customers. Biotechnologyis extremely expensive and there are serious questions about consumer acceptance," says David McLaughlin, Chiquita's senior director for environmental affairs. With scant funding from the companies, the banana genome researchers are focusing on the other end of the spectrum. Even if they can identify the crucial genes, they will be a long way from developing new varieties that small holders will find suitable and affordable. But whatever biotechnology' academic interest, it is the only hope for the banana. Without it, banana production worldwide will head into a tailspin. We may even see the extinction of the banana as both a lifesaver for hungry and impoverished Africans and as the most popular product on the world's supermarket shelves.

Question 1-3

Completethe sentences below with the WORDS in the passage.

Write your answers in boxes1-3 on your answer sheet

1 The banana was first eaten as a fruit by humans almost _____ years ago.

2 Bananas were first planted in _____.

3 The taste of wild bananas isadversely affected by its _____.

Question 4-10

Look at the following statements and match each statement with the correct person, A~F. Write the correct letter, A~F in boxes 4-10 on your answer sheet.

NB You may use any letter more than once.

4 A pest invasion may seriously damage the banana industry.

5 The effect of fungal infectionin soil Is often long-lasting.

6 A common imniifecturer gave up on to seding banmias for disuse resistant.

7 Banana disease may developresistance to chemical sprays.

8 A banana disease has destroyeda large number of banana plantations.

9 Consumers would not accept genetically altered crop.

10 Lessons can be learned from bananas for other crops.

Question 11-13

List of people

A Rodomiro Oritz

B David McLaughlin