Ok thank you, I also found a short answer[0]. It seems the carbon comes from the conversion of glucose; that is, from food. [0] http://www.smh.com.au/news/big-

Ok thank you, I also found a short answer[0]. It seems the carbon comes from the conversion of glucose; that is, from food. [0] http://www.smh.com.au/news/big-questions/we-breath-in-oxygen-and-breath-out-carbon-dioxide-where-does-thecarbon-come-from/2008/06/06/1212259085199.html http://www.smh.com.au/news/big-questions/we-breath-in-oxygen...