A Level Biology Practice Exam

Cellulose is primarily formed from which type of molecules?

1. Alpha glucose molecules

2. Gamma glucose molecules

3. Beta glucose molecules

4. Fructose molecules

The correct answer is: Beta glucose molecules

Cellulose is primarily composed of long chains of beta glucose molecules. The structural arrangement of beta glucose allows the formation of rigid, straight chains through hydrogen bonding between adjacent chains. This leads to the formation of microfibrils, which provide strength and support to plant cell walls. The unique configuration of beta glucose, which differs from alpha glucose, ensures that the polymer does not coil but instead forms strong fibers suitable for the structural role that cellulose plays in plants. In contrast, other options like alpha glucose and fructose do not form cellulose. Alpha glucose is the building block of starch, a storage polysaccharide, whereas fructose is a simple sugar that does not contribute to the formation of cellulose at all. Gamma glucose is not a standard classification in the context of carbohydrate structure. Thus, the correct choice is based on the specific type of glucose that leads to cellulose's unique properties and functions in plant biology.