Occurs in the mitochondria!!!
just an FYI:
cellular respiration is a process, chemical that is, that occurs in the mitochondria, which creates energy that come from the sugar ( created through the photosynthesis process) and oxygen , which then creates ATP (Adenosine triphosphate). ATP carries the energy that chemical process, which was referred to above, inside the cells.
Hopefully this helped and good luck. If you need me to further explain something or clarify just let me know.