Underground storage organs (such as potato tubers, roots of sweet potato, beet, carrot, etc.) generally store carbohydrates in the form of starch grains. How do they store starch when they do not get light for photosynthesis ?

Explanation

Starch is abundant reserve polysaccharide in plants. Each molecule of starch is branched of unbranched chain of a large number glucose units joined by glucosidec linkages. Starch grains can not pass through plasma membrane and, therefore, they are synthesized in those cells where they are stored. Synthesis of starch is an enzymatic process. It occurs inside the amyloplasts in storage organs. It does not rquire the presence of light. Light is required by green leaves which convert `CO_(2)` into glucose by the process of photosynthesis. The soluble sugar is then transported by pholem to the underground storage organs where it is converted into insoluble starch.