Answer:
The photosynthesis and cellular respiration are complementary to each other as they produce substrates for each other.
Photosynthesis is the process by which solar energy is converted into chemical energy. It consumes carbon dioxide, water, and solar energy in order to produce carbohydrate and oxygen (byproduct).
6 CO₂ + 6 H₂O + solar energy → C₆H₁₂O₆ + 6 O₂
Cellular respiration refers to the set of biochemical reactions which derive energy from carbohydrate and convert it into ATP (adenosine triphosphate), the energy currency of the cell.
It consumes carbohydrate and oxygen (products of photosynthesis) and produces carbon dioxide, water (substrates of photosynthesis) and energy (ATP).
C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O + energy