Answer: Both produce energy.
Explanation: Both provide each other with the necessary ingredients for the process to take place: glucose and oxygen for cellular respiration, carbon dioxide and water for photosynthesis.
When the concentration o molecules inside a cell is different form the concentration of molecules outside a cell, we can either call it hypertonic or a hypotonic solution, and the difference between the two concentrations is called a concentration gradient.
Hypertonic - name given to a solution that has a bigger concentration than the concentration in a cell.
Hypotonic - name give nto a solution that has a smaller concentration than the concentration in a cell.
Hope it helped,
BioTeacher101