Answer:
Photosynthesis is an endothermic reaction because it requires energy supply (in the form of photons)
Step-by-step explanation:
Photosynthesis is the process by which plants generates carbohidrates and oxigen, from carbon dioxide and water.
6CO2 + 6H2O ⇒ C6H12O6 + 6O2
The first step of photosynthesis requires energy supply in the form of a photons that are captured by pigments (chlorophyll for example), exciting electrons and this way allowing the occurence of following steps.