simplified representations of photosynthesis (top) and (one form of) chemosynthesis (bottom):

::: + H₂O + light -> CH₂O + O₂
::: + O₂ + 4 H₂S -> CH₂O + 4 S + 3 H₂O

In each of these cases, the end point is a polymer of reduced carbohydrate, (CH₂O)_n, typically molecules such as glucose