A chloroplast is one of three types of plastids, characterized by its high concentration of chlorophyll (the other two types, the leucoplast and the chromoplast, contain little chlorophyll and do not carry out photosynthesis).ne of the main functions of the chloroplast is its role in photosynthesis, the process by which light is transformed into chemical energy, to subsequently produce food in the form of sugars. Water (H 2 O) and carbon dioxide (CO 2) are used in photosynthesis, and sugar and oxygen (O 2) is made, using light energy.