Which of the following statement is not correct?

We are given a multiple choice question and we need to find which statement is not correct. Let's examine each option step by step.

Starting with option A: "Amylopectin is a branched polymer of $$\alpha$$-glucose." Amylopectin is a component of starch, which is found in plants. It is made up of glucose units connected by $$\alpha$$-1,4-glycosidic bonds in the chain and $$\alpha$$-1,6-glycosidic bonds at the branch points. Since the glucose units are in the $$\alpha$$-anomeric form and the structure is branched, this statement is correct.

Now option B: "Cellulose is a linear polymer of $$\beta$$-glucose." Cellulose is a structural polysaccharide in plant cell walls. It consists of glucose units linked by $$\beta$$-1,4-glycosidic bonds. The $$\beta$$-configuration leads to a straight-chain structure without branching. Therefore, this statement is correct.

Next, option C: "Glycogen is the food reserve of plants." Glycogen is a polysaccharide that serves as a storage form of glucose in animals and fungi. In animals, it is stored in the liver and muscles. However, plants store their energy primarily as starch, not glycogen. Starch is composed of amylose and amylopectin. Thus, attributing glycogen as the food reserve of plants is incorrect.

Finally, option D: "All proteins are polymers of $$\alpha$$-amino acids." Proteins are macromolecules formed by the polymerization of amino acids. The $$\alpha$$-amino acids have the amino group $$(-NH_{2})$$ attached to the carbon adjacent to the carboxyl group $$(-COOH)$$, known as the $$\alpha$$-carbon. All naturally occurring proteins are built from these $$\alpha$$-amino acids. Hence, this statement is correct.

After evaluating all options, we see that option C is not correct because glycogen is not the food reserve in plants; starch is.

Hence, the correct answer is Option C.