carbon dioxide, water as a byproduct released into atmosphere
Explanation:
Cellular respiration is the inverse of photosynthesis, photosynthesis is the light dependent reactions and cellular respiration is the light independent reactions.
Photosynthesis:
Light + H2O + CO2 -> C6H12O6 + O2
Cellular respiration:
C6H12O6 + O2 -> CO2 + H2O