Answer the following question given this paragraph: 

In biological systems, matter is continuously changing states as well. For example, carbon in the form of the gas carbon dioxide is changed into glucose, a solid. This change, of course, occurs during photosynthesis. During cellular respiration, carbons from the glucose molecule are changed back into the carbon dioxide gas.


Q: During cellular respiration, carbons from the glucose molecule are changed back into what gas?


A:
carbon dioxide