首页
登录
职称英语
If you go down to the woods today, you may meet high-tech trees—genetically
If you go down to the woods today, you may meet high-tech trees—genetically
游客
2024-04-13
38
管理
问题
If you go down to the woods today, you may meet high-tech trees—genetically modified to speed their growth or improve the quality of their wood. Genetically-engineered food crops have become increasingly common, albeit controversial, over the past ten years. But genetic engineering of trees has lagged behind.
Part of the reason is technical. Understanding, and then altering, the genes of a big pine tree are more complex than creating a better tomato. While tomatoes sprout happily, and rapidly, in the laboratory, growing a whole tree from a single, genetically altered cell in a test tube is a tricky process that takes years, not months. Moreover, little is known about tree genes. Some trees, such as pine trees, have a lot of DNA—roughly ten times as much as human. And, whereas the Human Genome Project is more than half-way through its task of isolating and sequencing the estimated 100, 000 genes in human cells, similar efforts to analyze tree genes are still just saplings(幼苗).
Given the large number of tree genes and the little that is known about them, tree engineers are starting with a search for genetic "markers". The first step is to isolate DNA from trees with desirable properties such as insect resistance. The next step is to find stretches of DNA that show the presence of a particular gene. Then, when you mate two trees with different desirable properties, it is simple to check which offspring contain them all by looking for the genetic markers. Henry Amerson, at North Carolina State University, is using genetic markers to breed fungal resistance into southern pines. Billions of these are grown across America for pulp and paper, and outbreaks of disease are expensive. But not all individual trees are susceptible. Dr. Amerson’s group has found markers that distinguish fungus-resistant stock from disease-prone trees. Using traditional breeding techniques, they are introducing the resistance genes into pines on test sites in America.
Using genetic markers speeds up old-fashioned breeding methods because you no longer have to wait for the tree to grow up to see if it has the desired traits. But it is more a sophisticated form of selective breeding. Now, however, interest in genetic tinkering(基因修补)is also gaining ground. To this end, Dr. Amerson and his colleagues are taking part in the Pine Gene Discovery Project, an initiative to identify and sequence the 50,000-odd genes in the pine tree’s genome Knowing which gene does what should make it easier to know what to alter. [br] Compared with genetic engineering of food crops, genetic engineering of trees _____.
选项
A、began much later
B、has developed more slowly
C、is less useful
D、was less controversial
答案
B
解析
本文并没有提到树木基因改良技术从什么时候开始,所以有可能树木的基因改良技术和别的基因改良技术在开始的时间上相差不大,但在所取得的成果方面却有很大的差别,因此,本题关键在于理解首段末句中的lag behind指的是程度上的落后,而非时间上的落后,故B正确。
转载请注明原文地址:http://tihaiku.com/zcyy/3553585.html
相关试题推荐
在经济增速放缓的大背景下,作为推动新型城镇化建设的重要载体,科技同区(high-techzone)建设至关重要。在创新成为重要经济驱动力的今天,科技园区
Ifyougodowntothewoodstoday,youmaymeethigh-techtrees—genetically
Ifyougodowntothewoodstoday,youmaymeethigh-techtrees—genetically
Ifyougodowntothewoodstoday,youmaymeethigh-techtrees—genetically
Ifyougodowntothewoodstoday,youmaymeethigh-techtrees—genetically
Ifyougodowntothewoodstoday,youmaymeethigh-techtrees—genetically
Ifyougodowntothewoodstoday,youmaymeethigh-techtrees—genetically
Ifyougodowntothewoodstoday,youmaymeethigh-techtrees—genetically
Ifyougodowntothewoodstoday,youmaymeethigh-techtrees—genetically
转基因食品(GeneticallyModifiedFood;GMF)是利用基因工程技术生产的食品。它具有产量高、营养丰富、抗病力强等优势,但也存在明
随机试题
FlorenceNightingaleenteredthehospitalandwasappalledandhorrifiedby
WantedxxxForeignLanguageInstituteisaforei
除了扫墓,人们还参与包括荡秋千、放风筝等各种活动。Apartfromsweepingthetombs,peoplealsotakepartin
关于事故隐患控制,要对存在隐患的安全设施、过程和行为进行控制,需确保( )。A
《宝玉挨打》中,说“你但凡听我一句话,也不到这个分儿”这句话的是( )A.袭人
某综合性信息系统建设工程中,通信工程专业监理工程师编制了详尽的监理实施细则,内容
8月6日18时,驾驶员甲驾驶装满液氯的槽罐车驶入某高速公路B56段,20时许,槽
患者,男,25岁,因饮食不洁导致呕吐、腹泻、发热就诊。护士为其进行评估之后,作出
在单一法人客户的财务状况分析中,财务比率内容主要包括( )。A.负债比率 B
2011年,我国青岛海事法院受理了几起承运人无正本提单交付货物的案件,根据200
最新回复
(
0
)