• Question: why are plants alive

    Asked by anon-351109 on 22 Mar 2023.
    • Photo: Nikolai Adamski

      Nikolai Adamski answered on 22 Mar 2023:


      I am not sure what exactly you’re asking, but I’ll try answer what I think you’re asking.

      The earliest signs of life on Earth are ~3.5 billion years old. Since then, different organisms have evolved and gone extinct again. All life on Earth is based around cells: there are single-celled organisms like bacteria, or multi-cellular (consisting of many cells) organisms like plants and animals.
      We consider these organisms alive because they have a metabolism (they convert chemicals into energy or vice versa), they grow, and they can reproduce by themselves (there are a few more characteristics of life, but I’ll leave it at that).
      Plants fulfill the characterists for life, i.e. they can grow and reproduce and they convert light energy into chemicals (sugars) or break sugars down for energy.

      Something that does not fulfill the criteria for life are viruses: they cannot reproduce by themselves (they need a host for that) and they have no metabolism of their own (they hijack the hosts metabolism).

      I hope that answers your question. Leave me a comment if it does not or if you want to know more 🙂

    • Photo: Sam Mugford

      Sam Mugford answered on 23 Mar 2023:


      Exactly how you decide if something is alive is suprisingly tricky. There are some things that scientists argue about whether they are alive or not- most often viruses. However there is no doubt that plants are alive, just becuase they don’t move very much doesn’t mean that they’re not alive.

      When I was at school I remember learning an acronym for the characteristics of living things, MERRING:

      Movement
      Excretion
      Reproduction
      Respiration
      Irritability
      Nutrition
      Growth

      Some of them seem a bit strange, Irritability just means that something responds to things in it’s environment, plants certainly do that. Do plants move? All of them are capable of some movement, it might just be lifting their leaves up and down in rhythm with sunlight. by this definition plants are alive, but viruses are not

      There are other deifinations of life, I like to think of anything that can reproduce as alive. If it can make copies of itself, and these copies can have mistakes in them, then evolution will be able to act on them and they might end up becoming more complex. by this definition viruses are alive. Also it means that some computer programs are alive! I for one, welcome our new robot overlords.

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