Answer:
Photosynthesis releases oxygen; cellular respiration releases CO2. However, do not take this to mean that car emissions would be an example of cellular respiration; it is, as the name implies, done by living cells/organisms. Decomposition would instead be a great example of cellular respiration; the decomposers need to break down their bodily sugars/other chemical storers of energy to do their job of... well, decomposing. Some major organisms that do photosynthesis are algae, some prokaryotes, and plants do photosynthesis. And lastly, remember that most actions of organisms, such as feeding, requires the expenditure of energy, or cell respiration.
