Here's why:

* Structure: Starch is a polymer made up of many glucose molecules linked together. This long chain structure makes it a large molecule.

* Function: Starch is the primary way plants store energy. It's a readily available source of glucose for the plant, and for humans who consume it.

* Types: There are two main types of starch: amylose and amylopectin. Amylose is a linear chain of glucose molecules, while amylopectin is a branched chain. Both are large molecules.

Other examples of large carbohydrate molecules include:

* Cellulose: The main structural component of plant cell walls.

* Glycogen: The storage form of glucose in animals.

* Chitin: A structural polysaccharide found in the exoskeletons of insects and crustaceans.

Let me know if you'd like to know more about any of these!