【科学60秒】彼之砒霜吾之蜜糖_英语听力练习mp3下载-科学-沪江听力酷

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【科学60秒】彼之砒霜吾之蜜糖

听力简介：

只写5个空即可，最后一个空和第一个空的词一样，不用单写出来。
Life on Earth requires six basic ingredients—carbon, hydrogen, nitrogen, oxygen, sulfur and phosphorus. Those six elements are the ____1____ for DNA and RNA, along with proteins and fats. Which means they're essential for life—as we know it. But it might be time to update that list. Because scientists have found a bacterium that can do without phosphorus—live on arsenic instead.
The researchers had a ____2____ a bug like this might exist, because arsenic has some ____3____ in common with phosphorus. So they collected mud from California's Mono Lake, where the waters are naturally salty, and laced with arsenic. Back in the lab, they cultured microbes from that mud. But instead of adding phosphorus to the cultures to help the bugs grow, they added varying levels of arsenic.
One bacterial ____4____ continued to thrive. And tests confirmed that the organisms ____5____ the lack of phosphorus by building their DNA with arsenic instead. The research appears in the journal Science.
This is the first known life form that seems to be able to swap out one of life's fundamental ____1____ with another element. So for astrobiologists hunting for life in space, don’t rule out places filled with poison.
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