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SSS 2011-08-02

时间:2011-09-05 03:33来源:互联网 提供网友:gmeng   字体: [ ]
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    (单词翻译:双击或拖选)

 Plants are sitting ducks for every hungry herbivore that wanders past. But for some greens, a little grazing is the best thing that can happen. They grow back faster and fuller and make more seeds than they would have if left alone. Now scientists know how they do it—by stockpiling their DNA1. The findings appear in the journal Ecology. 

 
Most animals have two full sets of chromosomes2: one inherited from mom and one from dad. But plants don’t play by the same rules. Banana plants have three full sets; strawberries eight. And plants that get noshed on may take a similar tack3.
 
Scientists took two strings4 of plants: one that comes back strong after grazing, another that wilts5. And they found that the plants that bounce back after clipping boost their DNA content—some of their cells go from having 10 chromosomes to having 320. 
 
The added DNA may allow the plants to rapidly make the proteins they need to grow and to produce seeds. And the size of the nucleus6 needed to contain all those chromosomes may make those cells bigger and bigger cells means a bigger plant. So chewed-on plants can fight back, and they are not afraid to go nuclear. 
 
Thanks for the minute. For Scientific American’s 60-Second Science, I’m Karen Hopkin.

点击收听单词发音收听单词发音  

1 DNA 4u3z1l     
(缩)deoxyribonucleic acid 脱氧核糖核酸
参考例句:
  • DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
  • Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。
2 chromosomes 11783d79c0016b60332bbf1856b3f77d     
n.染色体( chromosome的名词复数 )
参考例句:
  • Chromosomes also determine the sex of animals. 染色体也决定动物的性别。 来自《简明英汉词典》
  • Each of four chromosomes divide longitudinally. 四种染色体的每一种都沿着纵向分裂。 来自《现代汉英综合大词典》
3 tack Jq1yb     
n.大头钉;假缝,粗缝
参考例句:
  • He is hammering a tack into the wall to hang a picture.他正往墙上钉一枚平头钉用来挂画。
  • We are going to tack the map on the wall.我们打算把这张地图钉在墙上。
4 strings nh0zBe     
n.弦
参考例句:
  • He sat on the bed,idly plucking the strings of his guitar.他坐在床上,随意地拨着吉他的弦。
  • She swept her fingers over the strings of the harp.她用手指划过竖琴的琴弦。
5 wilts fecb32ceb121b72a2dc58d87218665f8     
(使)凋谢,枯萎( wilt的第三人称单数 )
参考例句:
  • The bacteria may gain entry and develop internally as in wilts and stunts. 当植株产生萎蔫或矮化症时细菌可进入体内繁殖。
  • The bacteris may gain entry and develop internally as in wilts and stunts. 当植株产生萎蔫或矮化症时细菌进入体内繁殖。
6 nucleus avSyg     
n.核,核心,原子核
参考例句:
  • These young people formed the nucleus of the club.这些年轻人成了俱乐部的核心。
  • These councils would form the nucleus of a future regime.这些委员会将成为一个未来政权的核心。
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