What are the function of glycogen, starch, cellulose and chitin
Glycogen: This is a very common form of carbohydrate occurring in fungi. In yeast, a unicellular fungus, it occurs to the extent of about 30% of the dry weight of the plant. It is not found in higher plants but is widely distributed among animals and is, therefore, sometimes called 'animal starch'.
Starch: Starch grains occur as a reserve food in all green plants in their storage organs. Starch is always derived from sugar, either in the leaf by the chloroplasts or in the storage organ by the leucoplasts.
Cellulose: Cellulose, an insoluble carbohydrate, is the chief constituent of the cell walls of all plants with the exception of fungi. Many bacteria utilize cellulose as food. They secrete the enzyme cellulose to hydrolyse it to glucose for assimilation.
Chitin: In the majority of fungi, and sometimes also in algae, the cell walls are made of a substance called chitin, a complex carbohydrate allied to cellulose to some extent.