• Question: why do trees give us oxygen?

    Asked by emilyxoxo to Marcus on 16 Mar 2012.
    • Photo: Marcus Gallagher-Jones

      Marcus Gallagher-Jones answered on 16 Mar 2012:

      They don’t give us oxygen so to speak but they do produce it as a by-product of photosynthesis. There are some theories as to why they evolved this ability mainly revolving around the fact that several billion years ago our planets atmosphere was mostly CO2 with very little free oxygen. Organisms developed the ability to photosynthsise (create sugars from water and CO2) and shift the oxygen levels. It’s though that this is what allowed other forms of life to evolve, so without plants we never would have come to be on this planet, pretty cool ey.