Question

what are the advantages of the respective properties in each case regarding celluose and starch?

Answer 1

Both are polymers of carbohydrates- polysaccharides.
Starches are carbohydrates in which 300 to 1000 glucose units join together. It is a polysaccharide which plants use to store energy for later use. Starch forms in grains with an insoluble outer layer which remain in the cell where it is formed until the energy is needed. It can then be broken down into soluble glucose units. Starches are of smaller size than cellulose units, and can be more readily used for energy. In animals, the equivalent of starches is glycogen, which can be stored in the muscles or in the liver for later use.
Cellulose molecules on the other hand are straight chains, and the fibers which result from collections of cellulose molecules form the supporting structures of plants. Even though human digestion cannot break down cellulose for use as a food, animals such as cattle and termites rely on the energy content of cellulose. They have protozoa and bacteria in their intestines- the intestinal microflora, which have the necessary enzymes in their digestive systems. Cellulose in the human diet is needed for fiber.