Name three naturally occurring polymers important for life.

The importance of proteins, starch, and cellulose as naturally occurring polymers in biological systems can be highlighted as follows:

Proteins are essential macromolecules composed of amino acids linked together in long chains. They perform a myriad of functions in living organisms, including serving as enzymes that catalyze biochemical reactions, providing structural support in cells and tissues, and playing critical roles in cell signaling and immune responses.

Starch is a storage polysaccharide primarily found in plants. It consists of numerous glucose units connected by glycosidic bonds, allowing it to serve as an energy reserve. When plants need energy, enzymes break down starch into glucose, which can then be utilized for cellular respiration.

Cellulose is another vital polymer, also composed of glucose units. However, unlike starch, cellulose provides structural support to plant cell walls, helping maintain their rigidity and strength. It is a key component of dietary fiber in human nutrition, although humans cannot digest it.

These three polymers illustrate the diversity of structure and function that naturally occurring polymers can have, demonstrating their significance in sustaining life processes.