Which statement best compares the processes of photosynthesis and cellular respiration? only photosynthesis produces carbon dioxide. only cellular respiration is required to sustain life. both occur in plant and animal cells. both convert energy from one form to another.

The right answer is Both convert energy from one form to another.  

Photosynthesis is a biochemical reaction that takes place only in plants and not in animals.

Photosynthesis creates energy in the form of carbohydrate from light energy, oxidizing water and reducing carbon dioxide.

Cellular respiration is the set of metabolic processes that convert the chemical energy contained in carbohydrates (such as glucose) into ATP (adenosine triphosphate), an energetic substrate used by the cell.