Final answer:
A starch molecule is best described as a chain of thousands of glucose molecules. It includes amylose, composed of unbranched chains, and amylopectin, which has branched chains due to 1-6 glycosidic bonds.
Step-by-step explanation:
The statement that best describes a starch molecule is: "A starch molecule is a chain of thousands of glucose molecules." Starch is a polysaccharide composed of glucose monomers linked together by glycosidic bonds. Specifically, it consists of two types of molecules: amylose, which is an unbranched chain of glucose units connected by 1-4 glycosidic bonds; and amylopectin, which is a branched molecule with 1-6 glycosidic bonds at the branching points.
Starch serves as a primary source of dietary energy for humans and is the chief carbohydrate found in plants. It is broken down into smaller molecules like maltose and glucose by enzymes, which can then be absorbed by cells.