单细胞生物







大腸桿菌放大10000倍



生命演化历程


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水

单细胞生物

光合作用

真核生物

多细胞生物


陆生生物

恐龙

哺乳动物

被子植物

 




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地球的诞生（-4540）



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水的起源（英语：Origin of water on Earth）



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生命起源
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后期重轰炸期



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氧气起源（英语：Geological history of oxygen）



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氧气泛布于大气



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大氧化事件



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有性生殖起源




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寒武纪大爆发



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人类起源


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时间轴以百万年为单位


生物可以根据构成的細胞數目分爲单细胞生物和多细胞生物。单细胞生物只由单个细胞组成，而且经常会聚集成为细胞集落。單細胞生物能獨立完成新陳代謝及繁殖等活動。


地球上最早的生物大約在距今35億至41億年前形成，原核生物是最原始的生物，如細菌和藍綠藻且是在溫暖的水中發現。


单细胞生物包括所有古细菌和真细菌和很多原生生物。根据旧的分类法有很多动物，植物和真菌多是单细胞生物。变形虫算作单细胞动物，它的一些种类却算作粘菌，带鞭毛的鞭毛虫如眼虫有时被归为单细胞藻类或者是单细胞动物。新的分类法中，所有的真核单细胞生物都算作原生生物。


粘菌根据最近的研究认为可以独立成界，虽然他们在正常情况下为单细胞，但其直径大小可达80厘米。它可以勉强被归到真菌中，因为它们也会呈现出类似变形虫的状态。


单或多细胞生物的分类只是描述性的，并不能提供任何亲缘、新陈代谢、构造和习性方面的信息。



参見


  • 多細胞生物


外部连結




  • Einzeller Video[永久失效連結]

  • 单细胞植物和单细胞动物的区别




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