Plant cells make energy  by the process called photosynthesis,  in which chlorophyll in the chloroplasts captures unusable regular sunlight.   The absorbed sunlight is combined with water and carbon dioxide.  During photosynthesis oxygen is released and the plant cell makes a sugar called glucose.   This glucose is stored in the mitochondria.  Cellular respiration occurs to convert the food into energy the plant cell can use.    This energy helps the plant to grow.