Cellulose as plant structural polymer

Steps:

• Identify common biological polymers: carbohydrates (starch, cellulose), proteins, lipids.
• Recall structural role in plants: cellulose forms rigid cell walls for support.
• Examine diagrams: assume A is starch (energy storage), B is protein (enzymes/muscles), C is lipid (membranes/energy), D is cellulose (beta-glucose links).
• Select D as it matches cellulose's role.

Why D is correct:

• Cellulose is a polymer of beta-glucose units linked by 1-4 glycosidic bonds, providing tensile strength in plant cell walls.

Why the others are wrong:

• A: Starch stores energy in plants, not structural.
• B: Proteins form structures like muscles but not plant cell walls.
• C: Lipids form membranes but are not polymers with structural roles in plants.

Final answer: D