What type of polysaccharide is starch primarily composed of?

Starch is primarily composed of D-glucose, a fundamental hexose sugar. It is a polysaccharide that serves as an energy storage molecule in plants. Starch is made up of two main components: amylose and amylopectin, both of which are polymer chains of D-glucose units linked together by glycosidic bonds.

The structure of starch allows plants to efficiently store glucose, which can later be broken down into glucose monomers when energy is needed. When starch is consumed by humans and other organisms, it is broken down into glucose through enzymatic processes, such as hydrolysis, starting in the mouth and continuing in the digestive system. The use of D-glucose as the monomeric unit is crucial because it is readily utilized by cells for energy production through processes like glycolysis and the citric acid cycle.

In summary, the correct answer is B, as starch’s primary composition consists exclusively of D-glucose molecules.