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  3. A bite of a cookie containing peanuts could cause the airway to constrict fatally. Sharing a toy with another child who had earl

A bite of a cookie containing peanuts could cause the airway to constrict fatally. Sharing a toy with another child who had earl

admin2014-12-11  3
问题     A bite of a cookie containing peanuts could cause the airway to constrict fatally. Sharing a toy with another child who had earlier eaten a peanut butter and jelly sandwich could raise a case of hives. These are the scenarios that "make your bone marrow turn cold" according to L. Val Giddings, vice president for food and agriculture of the Biotechnology Industry Organization, also the father of a four-year-old boy with a severe peanut allergy. Peanuts are only one of the most allergenic foods; estimates of the number of people who experience a reaction to the beans hover around 2 percent of the population.
    Giddings says that peanuts are only one of several foods that biotechnologists are altering genetically in an attempt to eliminate the proteins often acting as allergen that do great harm to some people’s immune systems. Although soy allergies do not usually cause life-threatening reactions, the scientists are also targeting soybeans, which can be found in two thirds of all manufactured food, making the supermarket a minefield for people allergic to soy. Biotechnologists are focusing on wheat, too, and might soon expand their research to the rest of the "big eight" allergy-inducing foods: tree nuts, milk, eggs, shellfish and fish.
    Last September, for example, Anthony J. Kinney, a crop genetics researcher at DuPont Experimental Station in Wilmington, Del. , and his colleagues reported using a technique called RNA interference(RNAi)to silence the genes that encode p34, a protein responsible for causing 65 percent of all soybean allergies. RNAi exploits the mechanism that cells use to protect themselves against foreign genetic material; it causes a cell to destroy RNA transcribed from a given gene, effectively turning off the gene.     Whether the public will accept food genetically modified to be low-allergen is still unknown. Courtney Chabot Dreyer, a spokesperson for Pioneer Hi-Bred International, a subsidiary of DuPont, says that the company will conduct studies to determine whether a promising market exists for low-allergen soy before developing the seeds for sale to farmers. She estimates that Pioneer Hi-Bred is seven years away from commercializing the altered soybeans.
    Doug Gurian-Sherman, scientific director of the biotechnology project at the Center for Science in the Public Interest—a group that has advocated enhanced Food and Drug Administration oversight for genetically modified foods—comments that his organization would not oppose low-allergen foods if they prove to be safe. But he wonders about "identity preservation" a term used in the food industry to describe the deliberate separation of genetically engineered and nonengineered products. A batch of non-engineered peanuts or soybeans might contaminate machinery reserved for low-allergen versions, he suggests , reducing the benefit of the gene-altered food. Such issues of identity preservation could make low-allergen genetically modified foods too costly to produce, Chabot Dreyer admits. But, she says, "It’s still too early to see if that’s true. "
From Paragraph 3, we can know that RNAi ______.
选项 A、can deprive cells of certain mechanism
B、can protect cells against foreign genetic material
C、can be effective on 34 kinds of genes
D、can cause soybean allergies
答案A
解析 该题题干中出现了明显的段落提示词和问题关键词RNAi，有利于考生迅速定位答案位置；然后进一步对该段内容进行详细解读，明确RNAi技术如何发挥作用；本题难点在于原文相关句子比较复杂，要求考生具备快速划分长难句，抓住句子主要含义的能力。
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