首页
登录
职称英语
The Debate over Genetically Modified Foods •Rice
The Debate over Genetically Modified Foods •Rice
游客
2023-09-12
18
管理
问题
The Debate over Genetically Modified Foods
•Rice with built-in Vitamin A that can help prevent blindness in 100 million children suffering from Vitamin A deficiency
•A tomato that softens more slowly, allowing it to develop longer on the vine and keep longer on the shelf
•Potatoes that absorb less fat when fried, changing the ever-popular French fries from junk food into a more nutritional food
•Strawberry crops that can survive frost
These are some of the benefits promised by biotechnology. The debate over its benefits and safety, however, continues. Do we really need to fear mutant (突变体) weeds, killer tomatoes, and giant com and will the benefits be delivered?
Conventional Breeding Versus Genetically Modified (GM) Crops
For thousands of years farmers have used a process of selection and cross breeding to continually improve the quality of crops. Even in nature, plants and animals selectively breed, thus ensuring the optimum gene pool for future generations. Traditional breeding methods are slow, requiring intensive labor: While trying to get a desirable trait in a bred species, undesirable traits will appear and breeders must continue the process over and over again until all the undesirables are bred out.
In contrast, organisms acquire one specific gene or a few genes together through genetic modification, without other traits included and within a single generation. However, this technology too is inherently unpredictable and some scientists believe it can produce potentially dangerous results unless better testing methods are developed.
Traditional breeding is based on sexual reproduction between, like organisms. The transferred genes are similar to genes in the cell they join. They are conveyed in complete groups and in a fixed sequence that harmonizes with the sequence of genes in the partner cell. In contrast, bioengineers isolate a gene from one type of organism and splice (接合) it haphazardly into the DNA of a dissimilar species, disrupting its natural sequence. Further, because the transplanted gene is foreign to its new surroundings, -it cannot adequately function without a big artificial boost.
One of the main differences between conventional and genetically modified crops is that the former involves crosses either within species or between very closely related species. GM crops can have genes either from closely related species or from distant species, even bacteria and viruses.
Benefits: One Side of the Debate
•Economical benefits
GM supporters tell farmers that they stand to reap enormous profits from growing GM crops. Initially, the cost is expensive but money is saved on pesticides. To produce the GM crops, modern biotechnology is used which requires highly skilled people and sophisticated and expensive equipment. Large companies need considerable investments in laboratories, equipment and human resources, hence the reason why GM crops are more expensive for farmers than traditional crops. GM crops, farmers are told, are a far better option. It takes a shorter time to produce the desired product. It is precise and there are no unwanted genes.
•Herbicide-Resistant Crops
So what other advantages do GM crops hold for farmers? GM crops can be produced to be herbicide-resistant. This means that farmers could spray these crops with herbicide and kill the weeds, without affecting the crops. In effect, the amount of herbicide used in one season would be reduced, with a subsequent reduction in costs for farmers and consumers. For Ingard cotton, pest-resistance was built into the cotton, hence reducing and even removing the use of pesticides, which are not only expensive but, more importantly, harmful to the environment.
Biotechnology companies are even experimenting with crops that can be genetically modified to be drought- and salt-tolerant, or less reliant on fertilizer, opening up new areas to be farmed and leading to increased productivity. However, the claims of less herbicide usage with GM crops have till now not been independently supported by facts.
•Better Quality Foods
Even animals can be genetically modified to be leaner, grow faster, and consume less food. They could be modified to have special characteristics, such as greater milk production in cows. These modifications again lead to improved productivity for farmers and ultimately lower costs for the consumer. Modified crops could perhaps prevent outbreaks such as foot and mouth disease, which has devastated many farmers and local economies.
No such products have been released to date; however, some are under consideration for release. For example, GM salmon, capable of growing almost 30 times faster than natural salmon~ may soon be approved by the FDA (Food and Drug Administration) in the U.S. for release into open waters without a single study on the impact on human health or the environment.
Risks: the Other Side of the Debate
The major concerns of those who oppose GM foods center on the following:
•Environmental Damage
The problem with GM crops is that there is little known about what effect they will have in, say, 20 years time. The genetic structure of any living organism is complex and GM crop tests focus on short-term effects. Not all the effects of introducing a foreign gene into the intricate genetic structure of an organism are tested. Will the pests that a crop was created to resist eventually become resistant to this crop? Then there is always the possibility that we may not be able to destroy GM crops once they spread into the environment.
•Risk to Food Web
A further complication is that the pesticide produced in the crop may unintentionally harm creatures. GM crops may also pose a health risk to native animals that eat them. The animals may be poisoned by the built-in pesticides. Tests in the U.S. showed that 44% of caterpillars of the monarch butterfly died when fed large amounts of pollen (花粉) from GM corn.
•Cross-Pollination (授粉)
Cross-pollination is a concern for both GM crops and conventional breeding, especially with the more serious weeds that are closely related to the crops. With careful management this may be avoided. Genetic modification to herbicide-resistant crops could insert the gene that prevents the problem. The number of herbicide-tolerant weeds has increased over the years from a single report in 1978 to the 188 herbicide-tolerant weed types in 42 countries reported in 1997. They are an ever-increasing problem and genetic engineering promises to stop it. But will genes from GM plants spread to other plants, creating superweeds and superbugs we won’t be able to control?
•GM Mix-Ups
Humans can inadvertently eat foods that contain GM products meant as animal feed, i.e., crops modified for increased productivity in animals. This happened in the U.S., where traces of a StarLink GM crop, restricted to use only in feed, were found in taco shells. Apparently no one became iii, but other such occurrences may lead to health problems.
•Disease
Another concern is disease. Since some crops are modified using the DNA from viruses and bacteria, will we see new diseases emerge? What about the GM crops that have antibiotic-resistant marker genes? Marker genes are used by scientists to determine whether their genetic modification of a plant was successful. Will these antibiotic-resistant genes be transferred to microorganisms that cause disease? We already have a problem with ineffective antibiotics. How can we develop new drugs to fight these new bugs?
Conclusion
Proponents of GM crops claim that advantages may be many, such as:
•improved storage and nutritional quality
•pest- and disease-resistance
•selective herbicide-tolerance
•tolerance of water, temperature and saline extremes
•improved animal welfare
•higher yields and quality
However, until further studies can show that GM foods and crops do not pose serious threats to human health or the world’s ecosystems, the debate over their release will continue. Living organisms are complex and tampering with their genes may have unintended effects. It is in our common interest to support scientists and organizations concerned, such as Friends of the Earth who demand "mandatory labeling of these food products, independent testing for safety and environmental impacts, and liability for harm to be assumed by biotech companies". [br] Conventional breeding is a slow, predictable process.
选项
A、Y
B、N
C、NG
答案
B
解析
细节题 根据关键词 conventional breeding 查读小标题 Conventional Breeding Versus Genetically Modified (GM) Crops 下面第一段第三句Traditional breeding methods are slow...undesirable traits will appear and breeders must continue the process over and over again until all the undesirables are bred out.这说明传统作物培育过程长且结果难测,需要经过反复实验才能培育出优良品种。
转载请注明原文地址:https://tihaiku.com/zcyy/3008942.html
相关试题推荐
Theexistenceofghostsmaybedebated.ButtheimpactoftraditionalAsianb
TheEuropeanUnionhadapprovedanumberofgeneticallymodifiedcropsuntil
TheEuropeanUnionhadapprovedanumberofgeneticallymodifiedcropsuntil
Peoplewithpetsfindithardtobelieve,butscientistscontinuetodebatew
Peoplewithpetsfindithardtobelieve,butscientistscontinuetodebatew
Peoplewithpetsfindithardtobelieve,butscientistscontinuetodebatew
TheDebateoverGeneticallyModifiedFoods•Rice
TheDebateoverGeneticallyModifiedFoods•Rice
TheDebateoverGeneticallyModifiedFoods•Rice
TheDebateoverGeneticallyModifiedFoods•Rice
随机试题
施工现场事故的处理包括:()。A.施工现场水污染的处理 B.施工现场噪声污染
依据项目变更管理流程,项目中的正式变更手续应该由()来进行审批。A.项目经
“旅行者1号”空间探测器历经36年的人类星际探索,沿途探测①木星、②土星、③土卫
下列不属于变相公开发行股票、公司、企业债券的是( )。A.采用广告、电话、传真
以下转运机制中药物从生物膜高浓度侧向低浓度侧转运的是A.主动转运B.被动转运C.
以下哪个产品不是中国农业银行的“五金”产品系列之一?()。A.金葵花 B.金
属于栓剂水溶性基质的是A.蜂蜡 B.普朗尼克 C.羊毛脂 D.凡士林 E
一张商业承兑汇票金额为20万元,5月10日到期,付款人不能支付票款。根据《支付结
建立健全基本公共服务标准体系,明确中央与地方提供基本公共服务的质量水平和支出责任
下列关于水平遮阳,说法正确的是()。A.适用于南向及南向附近的窗口 B.适用
最新回复
(
0
)