Expert: Joy Ramos - 4/13/2006

Question
Below are 2 equations, one for photosynthesis and one for cellular respiration – please briefly explain where the  1st equation's product and byproducts come from and how they are used in the 2nd equation.

PHOTOSYNTHESIS:
                                                                      Chlorophyll          CH²O            O²
CO²   +     H²O   +      light   +                   +            
(Carbon      (Water)          (energy)                 enzymes   (carbohydrate)      (Oxygen)
Dioxide)



CELLULAR RESPIRATION:
                                                  Enzymes   CO²     +   H²O      +     36ATP
    CH²O   +         O²                       (Carbon     (water)      (energy)
(Carbo)            (Oxygen)         Dioxide)
(Celular respiration is not lining up the way I'm wanting it to look like, but you get the general idea.


Answer
Hi, Nick. The formatting of your question is a little confusing. I'm not sure which of the items you posted are the reactants and which ones are the products/byproducts. From how I understand it, though, carbohydrate and oxygen from photosynthesis originally comes from the carbon dioxide and water available to the plant cell, combined with sunlight (that activates enzymes in chlorophyll).  These carbohydrates can then be used in cellular respiration processes with enzymes involved in glycolysis (if no oxygen is present) and the Kreb's cycle (if oxygen is present) that breaks down the carbohydrates and uses oxygen as a final electron acceptor to produce ATP. Hope this helps.