Plant cells mostly store food as starch. Starch is a complex carbohydrate made up of many glucose molecules linked together in a branched or unbranched chain. Starch is synthesized in the chloroplasts of photosynthetic cells and stored in specialized organelles called amyloplasts, which are found in roots, tubers, seeds, and other storage organs of the plant. When the plant needs energy, it breaks down the starch into glucose molecules that can be used for cellular respiration.