GM Organisms_简答题试题答案

第1题

GM OrganismsBy far the most common genetically modified （GM) organisms are crop plants. Bu

GM Organisms

By far the most common genetically modified (GM) organisms are crop plants. But the technology has now been applied to almost all forms of life, from pets that glow under UV light to bacteria which form. HIV-blocking "living condoms" and from pigs bearing spinach(菠菜) genes to goats that produce spider silk.

GM tomatoes ,first appeared on British supermarket shelves in 1996 (a different fresh GM tomato first appeared in the US in 1994), but the consumer furore that surrounded GM technology did not erupt until February 1999. This was because a controversial study suggested that a few strains of GM potatoes might be toxic to laboratory rats. Those experiments, subsequently criticised by other experts, were carried out in Scotland by biochemist Arpad Pustzai.

What followed was a European anti-GM food campaign of near religious fervor. Spearheaded in the UK by environmental groups and some newspapers, the campaign would have far-reaching consequences. It culminated in an unofficial moratorium(延期付款) on the growth and import of GM crops in Europe and led to a trade dispute with the US.

GM crops are today very rare in Europe, strict labeling laws and regulations are in place for food (DNV = A bar codes), and public opinion towards the technology remains largely negative. Several UK government reports have offered qualified support for GM crops and produce, though they argue that the economic benefits of the technology are currently small. Some African nations have also opposed engineered crops, even to the point of rejecting international food aid containing them.

GM produce has been taken up with far less fuss in the US (where it does not have to be labeled), India, China, Canada, Argentina, Australia and elsewhere. However controversy over a type of GM corn -- only approved for animal feed -- which turned up in taco shells and other products stirred opinion in the US.

Biotech Revolution

The human race has methodically improved crop plants through selective breeding for many thousands of years, but genetic engineering allows that time-consuming process to be accelerated and exotic traits from unrelated species to be introduced. But not everyone agrees this represents progress.

The root of genetic engineering in crops lies in the 1977 discovery that soil bug Agrobacterium Tumefaciens can be used as a tool to inject potentially useful foreign genes into plants. With the help of that microbe, and other gene-implantation technologies such as gene guns, geneticists have developed a multitude of new crop types.

Most of these are modified to pest, disease or herbicide resistant, and include: soya, wheat, corn (maize), oilseed rape (canola), cotton, sugar beet, walnuts, potatoes, peanuts, squashes, tomatoes, tobacco, peas, sweet peppers, lettuce and onions ,. among others. The bacterial gene Bt is one of the most commonly inserted. It produces an insecticidal toxin that is harmless to people.

Supporters of GM technology argue that engineered crops -- such as vitamin A -- boosted golden rice or protein-enhanced potatoes -- can improve nutrition, that drought -- or salt-resistant varieties can flourish in poor conditions and stave off world hunger, and that insect-repelling crops protect the environment by minimising pesticide use.

Other plants have been engineered to improve flavour, increase shelf life, increase hardiness and to be allergen-free (see also: hay fever-free grass). Geneticists have even created a no-tears on ion to banish culinary(厨房的) crying, and novel caffeine-free coffee plants.

"Frankenfood" Fears

Critics fear that what they call" Frankenstein foods" could have unforeseen, adverse health effects on' consumers, producing toxic proteins (and allergens ) or transferring antibiotic-resistance and other genes to human gut bacteria to damagin

A．Y

B．N

C．NG

点击查看答案

第2题

Directions: In this part, you will have 15 minutes to go over the passage quickly and answ

er the questions on Answer Sheet 1.

For questions 1—4, mark

Y(for YES) if the statement agrees with the information given in the passage;

N(for NO) if the statement contradicts the information given in the passage;

NG(for NOT GIVEN) if the information is not given in the passage.

For questions 5—10, complete the sentences with the information given in the passage.

GENETICALLY MODIFIED FOODS

Are genetically modified crops an environmental dream come- true or a disaster in the making？ Scientists are looking for answers.

The world seems increasingly divided into those who favor genetically modified (GM) foods and those who fear them. Advocates assert that growing genetically altered crops can be kinder to the environment and that eating foods from those plants is perfectly safe. And, they say, genetic engineering which can induce plants to grow in poor soils or to produce more nutritious foods will soon become an essential tool for helping to feed the world's burgeoning population. Skeptics contend that GM crops could pose unique risks to the environment and to health risks too troubling to accept placidly. Taking that view, many European countries are restricting the planting and importation of GM agricultural products. Much of the debate hinges on perceptions of safety. But what exactly does recent scientific research say about the hazards？ The answers, too often lost in reports on the controversy, are served up in the pages that follow.

Two years ago in Edinburgh, Scotland eco - vandals stormed a field, crushing canola plants. Last year in Maine, midnight raiders hacked down more than 3,000 experimental poplar trees. And in San Diego, protesters smashed sorghum and sprayed paint over greenhouse walls.

This far - flung outrage took aim at genetically modified crops. But the protests backfired: all the destroyed plants were conventionally bred. In each case, activists mistook ordinary plants for GM varieties.

It's easy to understand why. In a way, GM crops—now on some 109 million acres of farmland worldwide—are invisible. You can't see, taste or touch a gene inserted into a plant or sense its effects on the environment. You can't tell, just by looking, whether pollen containing a foreign gene can poison butterflies or fertilize plants miles away. That invisibility is precisely what worries people. How, exactly, will GM crops affect the environment- and when will we notice？

Advocates of GM, or transgenic, crops say the plants will benefit the environment by requiring fewer toxic pesticides than conventional crops. But critics fear the potential risks and wonder how big the benefits really are. "We have so many questions about these plants," remarks Guenther Stotzky, a soil microbiologist at New York University. "There's a lot we don't know and need to find out."

As GM crops multiply in the landscape, unprecedented numbers of researchers have started fanning into the fields to get the missing information. Some of their recent findings arc reassuring; others suggest a need for vigilance.

Fewer Poisons in the Soil？

Every year U. S. growers shower crops with an estimated 971 million pounds of pesticides, mostly to kill insects, weeds and fungi. But pesticide residues linger on crops and the surrounding soil, leaching into groundwater, running into streams and getting gobbled up by wildlife. The constant chemical trickle is an old worry for environmentalists.

In the mid - 1990s agribusinesses began advertising GM seeds that promised to reduce a farmer's use of toxic pesticides. Today most GM crops—main

A．Y

B．N

C．NG

点击查看答案

第3题

Jim Boon is a hybrid kind of guy.He drives a Toyota hybrid to work, a Honda hybrid on week

Jim Boon is a hybrid kind of guy. He drives a Toyota hybrid to work, a Honda hybrid on weekends and, as a manager for Seattle public transit he recently placed the world's largest order for hybrid electric buses.

Now, with the biggest hybrid-bus fleet in the world, Seattle has become the main testing ground for a technology that claims it can drastically cut air pollution and fuel consumption. In the 1990s, demo fleets of 35 buses or fewer started cropping up in cities such as Tempe, Ariz. Sixteen of these early hybrids still service Genoa, Italy, where drivers switch from diesel to electric power when passing the city's downtown architectural treasures. But no city has gone as far as Seattle, which last year bought 235 GM hybrid buses at $ 645,000 a pop. When the final one rolls out this December, the region's bus system will be 15 percent hybrid.

But why Seattle, and why now？ The Pacific Northwest has long been a hotbed of both Green politics and cutting-edge technology. Fourteen years ago the Seattle area bought 236 Italian-made Breda buses to service a mile-long downtown tunnel. They were supposed to operate as clean electric trolleys underground, but the switching mechanism often failed and "the bus drove through the tunnel as a diesel," says Boon. "It was pretty loud and smoky. "

When the Bredas hit retirement age in 2002, Boon went shopping. He chose the GM buses because they use an automatic transmission and diesel boosters that provide power to scale inclines without strain. In hilly Seattle, the prospect of a hybrid that could climb like a diesel but accelerate without belching black fumes helped justify a price $ 200,000 higher than that of a regular bus. "The days of seeing a diesel pull away and pour out smoke are over," says Boon. "After we drove these hybrid buses across the country, I wiped a handkerchief inside the tailpipe. It came out spotless. "

Experts say buses are critical to realizing the hybrid dream of greater efficiency and cleaner air. It would take thousands of hybrid cars to save as many gallons of gas (750,000) as Boon expects his buses to save Seattle each year. GM claims that compared with conventional diesels, its new buses also churn out 90 percent less particulate matter—a known carcinogen. "Buses are a major source of pollution in any city," says Dave Kircher of the Puget Sound Clean Air Agency. "They operate where people are breathing this exhaust, so this is a major step forward in terms of emissions. "

And a major step forward in the marketplace: Philadelphia, Honolulu, Long Beach, Calif., and Albuquerque, N. M. , have all bought the GM buses in recent months. GM is now touting itself in ads as the top hybrid-bus innovator, but Siemens is among the global giants dueling GM for new business, and New York plans to deploy 325 BAE Systems hybrids by 2006. "There's room for competition," says James Cannon, editor of Hybrid Vehicles newsletter. Seems Seattle isn't the only city trying to leave grunge behind.

How does Genoa protect its architectural treasures？

A．Following Seattle's steps to reduce pollution.

B．Using electric power of the car.

C．Shifting the power of the hybrids to electric one when crossing.

D．Reducing the number of the buses crossing there.

点击查看答案

第4题

航行中船舶的横摇周期Tθ与GM的关系是____。

A.Tθ越大，GM越大

B.Tθ越大，GM越小

C.Tθ与GM关系的变化趋势不定

D.Tθ的大小与GM的大小无关