VCE Biology Unit 1 Area of Study (AOS) 1 Practice Test

Plant cell walls gain their rigidity from cellulose, a structural carbohydrate. It’s built from long, straight chains of glucose linked by beta-1,4 glycosidic bonds. Those beta linkages keep the chains straight, allowing many chains to pile up and form strong microfibrils that create a tough, supportive network in the wall.

Glycogen and starch, by contrast, are storage polysaccharides made from alpha-glucose. Glycogen is highly branched and used for quick energy in animals, while starch stores energy in plants. Chitin is structural in fungi and the exoskeletons of arthropods, made from N-acetylglucosamine, not a plant wall component. Therefore, cellulose is the carbohydrate that is structural in plants.