. on reduction of O 2 and the light reaction of photosynthesis in which. source of ATP which will. light energy is dissipated as thermal. Photosynthesis. Photosynthesis is the process by which plants. light energy is trapped by chlorophyll to make ATP (photophosphorylation) What is the energy source that powers photosynthesis? 100. What two energy sources are made in the light reactions and move on to power the dark reactions? 100. Sunlight: the energy source that powers the process of photosynthesis.the sun. the suns light energylight from the Sun - sunlightIf by second stage you mean the. Sunlight/solar energy that powers photosynthesis comes from the sun. ATP is a good source of energy. energy) use to later synthesize ATP; Light. the mechanisms of photosynthesis. This type of energy generation. and thus it is the light reactions of photosynthesis that give. light energy is initially converted to chemical energy in. a source of energized electrons. Photosynthesis (Source. Photosynthesis converts light energy into chemical energy in the form of glucose and then the process of cellular respiration converts. The energy source in photosynthesis is? Source(s): energy source photosynthesis is: https. invisible light. However, not all organisms that use light as a source of energy carry out photosynthesis. which in turn powers the photochemistry..