• Question: Why is it that animals and plants are different in that animals breathe in oxygen and breathe out carbon dioxide but plants do the opposite?

    Asked by SOPHIA M to Aaron, Abbey, Keith, Natalie, Pete on 16 Nov 2015.
    • Photo: Aaron Boardley

      Aaron Boardley answered on 16 Nov 2015:

      We breathe in oxygen to burn it with food to create energy, and create carbon dioxide as a waste product. A lot of people don’t realise that plants do this exact same thing too!

      However, plants do a different thing as well, in addition to this. They take in carbon dioxide and, using sunlight for energy, create their own food (as plants can’t eat like we can). The amount of carbon dioxide they take in this way as far more than the amount they release the other way, so the overall effect is that that take in carbon dioxide, and give out oxygen (even if they do the other way round a bit, too).

    • Photo: Natalie Garrett

      Natalie Garrett answered on 20 Nov 2015:

      Plants and animals evolved differently. We respire (we get energy by breaking down chemical stores like sugar, a process which requires oxygen and releases carbon dioxide) and actually, so do plants. But during the day, plants are also able to photosynthesise, so they can make chemical energy (sugar) by converting water and carbon dioxide into glucose, releasing oxygen in the process. Since we are unable to photosynthesise, we instead get our chemical energy that we use in respiration from the food we eat.

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