Two major functions of carbohydrates in plants are following
(a) Structural material for plant cell walls. The polysaccharide cellulose acts as the chief structural of the plant cell walls.
(b) Reserve food material. The polysaccharide startch is the major reserve food material in the plants. It is stored in seeds and act as the reserve food material for the tiny plant till it is capable of making its own food by photosynthesis.
