When plants photosynthesize, the net reactions are to turn water and carbon dioxide into sugars and oxygen, using energy from the sun.
When animals and other aerobic organisms obtain usable energy from sugars and other compounds, the net outcome is the inverse: turning sugars and oxygen into water and carbon dioxide.
Therefore, humans are net producers of ...
A cup is a non-standard unit of measurement for volume:
It usually varies between 200ml and 250ml.
In the U.S., it is 2.365882365 decilitres exactly (which is 236.5882365 millilitres exactly).