Dear student,
We take items of wheat , rice , potatoes etc. in form of food. They contain carbohydrates. During the process of digestion, carbohydrates are broken down into simpler substances such as glucose . During the process of respiration glucose molecules combine with oxygen in cells and produce energy large amount of energy. That's why respiration is considered as exothermic reaction . The reaction involved is-
C6H12O6 + 6 O2 --> 6CO2 + 6H2O +ENERGY
Photosynthesis is an endothermic reaction .Energy(from sun) is taken by the chlorophyll and pigments to carry out the process of photosynthesis . As we know that the reactions in which energy is absorbed are endothermic. Hence photosynthesis is an endothermic reaction .
6CO2 + 6H2O ------> C6H12O6 + 6O2
The energy taken in from sun is then stored in the bonds of glucose that are formed by the process of photosynthesis .
Regards