* Photosynthesis is the process where plants use sunlight, water, and carbon dioxide to produce their own food (glucose) and release oxygen. This process only occurs during daytime when sunlight is available.

* Respiration is the process where plants break down glucose (their food) to release energy for growth and other life functions. This process occurs all the time, both day and night.

So the answer is:

* Respiration occurs all the time (24/7).

* Photosynthesis occurs only during daytime.