美国科学60秒 SSS 2012-11-30_在线英语听力室_免费在线英语听力学习网站

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You might say blue-green algae¹ are optimists²: they put things in the best possible light—literally. Actually, the organisms aren’t really algae. They’re photosynthetic³ ocean bacteria. And they can fine-tune their photosynthetic apparatus⁴ to take advantage of the predominant wavelength⁵ of light. Now researchers have figured out how one of the world’s most abundant phytoplankton control their color change.

It all comes down to a single, light-sensitive enzyme⁶. In coastal⁷ waters where the surrounding light and water are green, specific proteins help catch green light. But in the deeper blue-colored waters, the color change activates⁸ an enzyme that replaces the green-light catching⁹ proteins with ones tuned¹⁰ for blue light. The finding is in the Proceedings¹¹ of the National Academy of Sciences.

The bacteria produce 20 percent of the planet’s oxygen and also consume carbon dioxide from the atmosphere. Researchers say understanding how the bacteria optimize¹² their photosynthesis¹³ may help inform climate change scientists. And medical researchers could also get ideas for pigments¹⁴ useful in medical research. Who knew pond scum could be so smart?

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1 algae
n.水藻，海藻
参考例句：
Most algae live in water.多数藻类生长在水中。 Algae grow and spread quickly in the lake.湖中水藻滋蔓。

2 optimists
n.乐观主义者( optimist的名词复数 )
参考例句：
Even optimists admit the outlook to be poor. 甚至乐观的人都认为前景不好。来自《简明英汉词典》 Optimists reckon house prices will move up with inflation this year. 乐观人士认为今年的房价将会随通货膨胀而上涨。来自辞典例句

3 photosynthetic
adj.光合的，促进光合作用的
参考例句：
In some plants photosynthetic products are stored in the form polyfructosans. 在有些植物中，光合作用产物是以多聚果糖的形式储藏。 Chlorotic or necrotic lesions were evidence of decreased photosynthetic tissues. 缺绿的或坏死的侵蚀斑便是减少了光合组织的证据。

4 apparatus
n.装置，器械；器具，设备
参考例句：
The school's audio apparatus includes films and records.学校的视听设备包括放映机和录音机。 They had a very refined apparatus.他们有一套非常精良的设备。

5 wavelength
n.波长
参考例句：
The authorities were unable to jam this wavelength.当局无法干扰这一波长。 Radio One has broadcast on this wavelength for years.广播1台已经用这个波长广播多年了。

6 enzyme
n.酵素，酶
参考例句：
Above a certain temperature,the enzyme molecule will become unfolded.超过一定温度，酶分子将会展开。 An enzyme that dissolves the fibrin of blood clots.能溶解血凝块中的纤维的酶。

7 coastal
adj.海岸的，沿海的，沿岸的
参考例句：
The ocean waves are slowly eating away the coastal rocks.大海的波浪慢慢地侵蚀着岸边的岩石。 This country will fortify the coastal areas.该国将加强沿海地区的防御。

8 activates
使活动，起动，触发( activate的第三人称单数 )
参考例句：
Activates the window and displays it in its current size and position. 激活窗口，保持当前的大小及位置不变。 Pulling out the alarm switch activates alarm and pushing it deactivates it. 闹钟的开和关是通过拔出和按入闹铃开关实现的。

9 catching
adj.易传染的，有魅力的，迷人的，接住
参考例句：
There are those who think eczema is catching.有人就是认为湿疹会传染。 Enthusiasm is very catching.热情非常富有感染力。

10 tuned
adj.调谐的，已调谐的v.调音( tune的过去式和过去分词 )；调整；（给收音机、电视等）调谐；使协调
参考例句：
The resort is tuned in to the tastes of young and old alike. 这个度假胜地适合各种口味，老少皆宜。 The instruments should be tuned up before each performance. 每次演出开始前都应将乐器调好音。来自《简明英汉词典》

11 proceedings
n.进程，过程，议程；诉讼(程序)；公报
参考例句：
He was released on bail pending committal proceedings. 他交保获释正在候审。 to initiate legal proceedings against sb 对某人提起诉讼

12 optimize
v.使优化 [=optimise]
参考例句：
We should optimize the composition of the Standing Committees.优化人大常委会组成人员的结构。 We should optimize our import mix and focus on bringing in advanced technology and key equipment.优化进口结构，着重引进先进技术和关键设备。

13 photosynthesis
n.光合作用
参考例句：
In apple trees photosynthesis occurs almost exclusively in the leaves.苹果树的光合作用几乎只发生在叶内。 Chloroplasts are the structures in which photosynthesis happens.叶绿体就是光合作用发生的地方。

14 pigments
n.（粉状）颜料( pigment的名词复数 )；天然色素
参考例句：
The Romans used natural pigments on their fabrics and walls. 古罗马人在织物和墙壁上使用天然颜料。来自辞典例句 The original white lead pigments have oxidized and turned black. 最初的白色铅质颜料氧化后变成了黑色。来自辞典例句