Starch is a naturally occurring polymer found in foods such as potatoes and bread. Describe the structure of starch as a polymer, and explain how starch is broken down in the human body and what happens to the products of this breakdown.

Starch is a polymer of glucose units linked by α‑1,4‑glycosidic bonds, forming long chains that can be straight (amylose) or branched (amylopectin). The glucose monomers are joined by covalent bonds, giving a high‑molecular‑weight polymer.

In the human body, starch is hydrolysed by the enzyme amylase (in saliva and pancreas). Amylase cleaves the α‑1,4‑glycosidic bonds, producing smaller sugars, mainly maltose and glucose.

The glucose produced is absorbed into the bloodstream and is either used immediately by cells for cellular respiration to release energy or stored as glycogen in liver and muscle.