Why is the spiral shape of a starch molecule significant?

The spiral shape of a starch molecule is significant because it allows for compact storage of glucose units. Starch is composed of long chains of glucose molecules, and its helical structure minimizes the space that these chains occupy, making it efficient for storage in plant cells. This compactness is crucial for plants, as it enables them to store large amounts of energy in the form of starch without taking up excessive space within the cells.

The spiral form also contributes to the molecule's stability, protecting the glucose units from being easily broken down by enzymes when not needed, which helps maintain energy reserves for the plant. In contrast, the other options do not accurately describe the primary significance of the spiral shape; they either pertain to aspects like digestion, photosynthesis, or solubility which are not directly influenced by the helical compactness of the starch molecule.