Which enzyme plays a role in converting glucose to starch?

The enzyme that plays a crucial role in converting glucose to starch is amylase. Amylase is responsible for breaking down starch and glycogen into simpler sugars, specifically maltose and dextrins, during digestion. However, it is also involved in the synthesis of starch from glucose.

In plants, the synthesis of starch from glucose units occurs through a process called polymerization. Amylase helps facilitate the formation of longer chains of glucose, allowing the formation of starch granules, which serve as an energy reserve for the plant. This process is essential for energy storage and regulation, especially during periods when photosynthesis is not occurring actively.

The other enzymes listed serve different functions. Cellulase breaks down cellulose, a structural component of plant cell walls; hexokinase is involved in the phosphorylation of glucose to form glucose-6-phosphate, an important step in glucose metabolism; and phosphorylase assists in the breakdown of glycogen and starch but does not play a direct role in the synthesis of starch from glucose. Therefore, amylase is the correct choice as it specifically relates to the conversion of glucose into starch.