If you're a bacterium your whole life is about swimming to nutrients and running away from things that would kill you.

假如你是一个细菌,你的一生将会在追逐养分,和逃避敌害中度过

耶鲁公开课 - 生物医学工程探索课程节选

Even if that beaker had all the nutrients that skin cells needed they wouldn't survive very well in solution, they tend to need to be stuck to a surface in order to survive.

即使供给它们所有所需的养分,它们也不能在溶液中正常存活,皮肤细胞倾向于贴壁生长

耶鲁公开课 - 生物医学工程探索课程节选