genetically modified food good or bad
- 1 0 年前最佳解答
Genetically modified food is food from plants that have been genetically altered to create desired qualities these qualities include improved resistance to diseases and tolerance to herbicides or extreme weather.
Genetically modified plants refer to plats that have had their genetic make-up modified by the artificial insertion of genes from a foreign source, such as other plants or animals. There are different types of genetically modified food crops, such as pest-resistant plants which can withstand pet attacks, herbicide-tolerant plants which are not affected by herbicides sprayed on them and plants with added nutritional value. The most common genetically modified food crops are potatoes, corn, soya beans and tomatoes. Other genetically modified food crops include cereals such as rice, wheat and barley.
It is estimated that about 40 per cent of the world's food crop are damaged by pests, low rainfall and other problems every year. These damaged crops have to be thrown away, resulting in a loss of income for the farmers. However, through research, scientists have created genetically modified food crops that are more resistant to such conditions. For example, a pest-resistant corn was created by inserting a bacterium, Bacillus thuringiensis(Bt), into a corn plant. As Bt is a natural pesticide, the Bt corn suffers less damage from insects. With fewer food crops being damaged, farmers who choose to grow pest-resistant genetically modified food crops such as the Bt corn may be able to enjoy an increase in their output and income. Some food crops have also been genetically modified to stay fresh for a longer period of time. Hence, the farmers who grow such genetically modified food crops can sell their produce to markets that are further away. In this way, farmers in less developed countries may be able to sell more of their crops to other countries and earn more money.
2009-11-01 15:30:25 補充：
Some genetically modified food crops are able to produce higher outputs than non- genetically modified food crops. For example, the cultivation of Super Rice, a type of genetically modified rice produces double the output of normal rice.
2009-11-01 15:31:01 補充：
The increase in food supply leads to a decline in food prices, making food more affordable in less developed countries. This can help reduce the problem of malnutrition and improve people's health.
2009-11-01 15:31:16 補充：
Some food crops have been genetically modified to have higher nutritional levels. For example, a genetically modified rice known as Golden Rice has been enriched with beta-carotene to supplement the lack of Vitamin A in rice diets in less developed countries.
2009-11-01 15:31:21 補充：
In the past, the lack of Vitamin A in less developed countries has resulted in one million children dying every year and 350000 becoming blind. The introduction of Golden Rice in less developed countries can help reduce the number of malnutrition cases.
2009-11-01 15:31:44 補充：
However, many people fear the potential health risks that might be associated with consuming genetically modified food, as some food substances used may cause allergies.
2009-11-01 15:31:50 補充：
For example, scientists have use lectin － a protein found in beans － in potatoes to prevent aphids from attacking potato plants. However, some people are allergic to lectin.
2009-11-01 15:32:12 補充：
Hence, people who are allergic to lectin fear that they may have allergic reactions if they unknowingly eat genetically modified potatoes that contain lectin. There is also the fear of the unknown consequences of consuming food that is not natural.
2009-11-01 15:32:15 補充：
For example, it was found in 2005, that a genetically modified pea caused health problems in research mice.
2009-11-01 15:32:52 補充：
Environmentalists have expressed concerns over how genetically modified food crops can affect biodiversity. For example, some pest-resistant plants are indirectly destroying harmless insects such as Monarch butterflies.
2009-11-01 15:33:00 補充：
In the 1980s, corn was genetically modified to express a toxin called the Bt toxin, which kills the European corn borer, a butterfly caterpillar that feeds on corn. This toxin was expressed even in the pollen of the Bt corn.
2009-11-01 15:33:10 補充：
When the larvae of the Monarch butterfly fed on plants that were dusted with Bt corn pollen, the larvae grew more slowly and died at a higher rate than larvae that were not exposed to the pollen. This may also affect the animals further up the food chain.
2009-11-01 15:33:21 補充：
As more species of plants and animals become extinct, biodiversity will be lost.
2009-11-01 15:34:07 補充：
Some genetically modified food crops may also genetically pollute natural crops that are not genetically modified. For example, when the pollen of a pest-resistant crop is carried by the wink or by insects to compatible natural crops,
2009-11-01 15:34:20 補充：
the offspring of the organic crops will also become pest-resistant. Since such gene pollution is irreversible, it will result in the loss of the natural plant species. This will in turn result in a loss of biodiversity.
2009-11-01 15:34:30 補充：
Gene pollution may also lead to the development of superweeds, which are herbicide-resistant. This happens when the herbicide-resistant gene is passed on to weeds from genetically modified crops that are herbicide-resistant. As a result, superweeds develop.
2009-11-01 15:34:36 補充：
The number of such weeds has been increasing over the years and stronger herbicides have to be use to remove them, This is a potentially serious problem.
2009-11-01 15:35:10 補充：
It is difficult to determine whether genetically modified food is good or bad. It is up to the consumers and their decisions.
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