• Question: Why can we on breathe with air (oxygen) and not another gas

    Asked by Najma A. to Dan, David, Dawn, Sian on 22 Jun 2016.
    • Photo: Dawn Lau

      Dawn Lau answered on 22 Jun 2016:

      Our cells need oxygen to survive – it is required for essential processes like making energy for cells, otherwise they would start to die. But air is a mixture of about 21% oxygen and 78% nitrogen, and the remainder is made up of other gases. We can’t actually breathe 100% pure oxygen for too long, otherwise you get oxygen poisoning!

    • Photo: David Robertson

      David Robertson answered on 22 Jun 2016:

      Crudely put, we need to “burn” food to create energy to let us live, much like a fire needs fuel and oxygen. Oxygen is the gas you need to “burn” the food.

    • Photo: Sian Thomas

      Sian Thomas answered on 22 Jun 2016:

      Good answers other scientists.

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