Both light-dependent and light-independed reactions of photosynthesis are similar in a way because they both require chemical energy to proceed.
Photosynthesis occurs in two successive stages. These stages are:
1) The light-dependent reactions
2) The light-independent reactions
The light dependent reactions absorb energy from sunlight and converts it into chemical energy. The chemical energy produced (ATP) by the light-dependent reactions is used by the light-independent reactions for it to function properly. The remaining chemical energy (ADP) in the light-independent reactions is returned to the light-dependent reactions to obtain more energized electrons.