what do plant photosynthesis and animal cellular respiration have in common?

Answer 1

Both processes have something to do with energy for the cell. Please note that cellular respiration happens in plants, too, not just in animals.

Each process makes what the other one needs to use, so that keeps life going!
Photosynthesis makes glucose and oxygen, but needs carbon dioxide and water.
Respiration makes carbon dioxide and water, but needs glucose and oxygen.