Answer: Both perform photosynthesis.
Explanation: Although, Cyanobacteria comes under bacteria but they are capable of trapping the sunlight and produce energy. That shows ancestral relationship between chloroplast and cyanobacteria.
Chloroplast are specialized structures in plant and algal cells. The main function of the chloroplast is to perform photosynthesis by capturing the sunlight with the help chlorophyll pigments and convert it into energy storage molecules called as ATP.