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
2023-08-14
30
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:https://tihaiku.com/zcyy/2924140.html
相关试题推荐
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
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
随机试题
Labelthemapbelow.Writethecorrectletter,A-l,nexttoquestions15-20.[im
Conversation:Thefollowingisanarticleaboutwebstation.Afterreadingi
[originaltext]W:I’msorry,butIcan’tletyoucheckoutthesebooks.M:What
检查尿中细胞时,至少应观察多少个高倍镜视野A.15个 B.2个 C.20个
患者,男性,33岁。高热,右上腹痛7天。B型超声波和CT检查提示肝脓肿,曾有胆道
王某与赵某于2017年12月结婚,2018年10月王某怀孕后因故流产。同年12月
下列选项中,不仅是操作风险计量的一种方法,更是一套完整的操作风险管理框架的计量方
李先生于2016年4月8日存入一笔10000元的定活两便存款,2016年5月8日
期货投资者可以根据所有公开的信息进行分析决策,如果认定期货市场是有效市场,那么投
下列统计指标中,属于总量指标的是()。A.人均国民生产总值 B.财政收入
最新回复
(
0
)