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The nitrogen cycle - Khan Academy
2016年6月9日 · Nitrogen-fixing microorganisms capture atmospheric nitrogen by converting it to ammonia— NH 3 —which can be taken up by plants and used to make organic molecules. The nitrogen-containing molecules are passed to animals when the plants are eaten.
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Watch a video explaining how nitrogen gas in the atmosphere is converted into usable forms for living organisms through the nitrogen cycle.
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The phosphorus cycle (article) | Ecology | Khan Academy
The slow cycling of phosphorus through the biosphere. How phosphorus-containing fertilizers can cause aquatic dead zones.
AI for Teachers - Khan Academy
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Review your understanding of the carbon cycle with this free article aligned to NGSS and AP standards.
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可汗学院 - Khan Academy
固氮微生物捕获大气氮将其转化成氨— NH 3 ，其可以被植物吸收以产生有机分子。. 当植物被吃掉后，含氮分子被传给动物。. 它们有可能被整合进动物的身体，或被分解并作为废物排出，例如尿液中的尿素。. 图片来源: 修改自 氮循环 由 Johann Dréo (CC BY-SA 3.0 ...
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