在职申硕英语考试

解析：{{B}}Passage Four{{/B}} Sci

来源:网考网在职申硕英语 所有评论

【单选题】{{B}}Passage Four{{/B}}

Scientists are hoping to eliminate malaria (疟疾) by developing a genetically modified mosquito that cannot transmit the disease. Malaria has long troubled the populations of SouthAmerica,Africa, andAsia, where mosquito bites infect up to 500 million people a year with this serious and sometimes fatal parasitic blood disease. For generations, scientists have been trying to eliminate malaria by developing new drugs and using pesticides (杀虫剂) to wipe out local mosquito populations.But these measure aren’t working--and some scientists, like Greg Lanzaro, say that because of drug resistance and population changes, malaria is actually more prevalent now than it was 20 years ago. Lanzaro says he has a better way to stop the spread of malaria: genetically modifying mosquitoes so they are unable to carry the disease.
Lanzaro and his. colleagues are planning a multi-year project to produce malaria-resistant mosquitoes--and he thinks they can do it within five years. "We can get foreign genes into mosquitoes and they go where they’re supposed to go," Lanzaro says, pointing out that scientists have already succeeded in genetically engineering mosquitoes that cannot transmit malaria to birds and mice.And, he says, scientists are quickly making progress on genes that block transmission of the disease to humans as well.
The most difficult part scientifically, Lanzaro says, is figuring out how to get the lab-engineered mosquitoes to spread their genes into natural populations.After all, he points out, it’s useless to engineer mosquitoes in the lab that can’t transmit malaria when there are millions out in the wild that can. To solve this problem, Lanzaro wants to load up a mobile piece ofDNA、with the malaria-resistant gene, and then insert it into a group of mosquito embryos. The malaria-resistant gene would be integrated directly into the mosquitoes’DNA, making it impossible for those mosquitoes to transmit the parasite that causes malariA、In this way a small group of lab-raised mosquitoes could be released into the wild, and by interbreeding with wild mosquitoes, eventually transmit the beneficial gene to the entire population.
What is the most difficult part of Lanzaro’s projectA．Spreading malaria-resistant genes into natural mosquito populations.
B．Raising malaria-resistant mosquitoes.
C．Making genes that block the transmission of malariA、
D．Identifying malaria-resistant genes.

网考网参考答案：A
网考网解析：
第三段第一句明确指出：该项实验的最难之处就是如何让实验室中的这些基因工程蚊虫把它们的基因传播到自然种群中去。故A项正确。其他三项从文中可推断都是已实现的。 document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>

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