A) Which chemicals would you expect to find at the top of the diagram?
Oxygen. Oxygen because both plants and animals need oxygen to breathe. When they inhale it's carbon dioxide, but when they exhale its oxygen.
B) Which chemicals would you expect to find at the bottom of the diagram?
Water. Water and carbon dioxide. Because respiration is getting the energy from chemicals to warm the body (animals & humans).
The equation of photosynthesis is the opposite or reverse of the equation of respiration.
Respiration and photosynthesis are two complementary processes. This is because the reactants in one process are the products in the other.
The equation of photosynthesis is; 6CO2 + 6H2O → C6H12O6 + 6O2 while the equation of respiration is; C6H12O6 + 6O2 → 6CO2 + 6H2O.
It implies that, at the top of the diagram, we have the reactants in respiration, which are C6H12O6 and O2, while at the bottom of the diagram; we have the reactants in photosynthesis, which are CO2 and H2O.