What is the primary energy reserve in plants like sweet potatoes?

The primary energy reserve in plants, such as sweet potatoes, is starch. Starch is a polysaccharide composed of numerous glucose units and serves as a critical energy storage compound in many plants. When plants undergo photosynthesis, they convert sunlight into chemical energy, which is stored in the form of starch in their tubers and roots.

Sweet potatoes, being root vegetables, store energy predominantly as starch, allowing them to survive periods of low light or unfavorable growing conditions. When the plant requires energy, the starch can be broken down into glucose through enzymatic processes during respiration or germination.

While plants utilize proteins for growth and metabolic functions, proteins are not primarily stored as an energy reserve, as they play more of a structural and functional role. Sucrose, a simpler sugar, functions mainly in transport within the plant rather than storage, serving as an immediate energy source. Cellulose, on the other hand, is a major component of the plant cell wall, providing structural support rather than serving as an energy reserve. Hence, starch is the most suitable answer when considering energy reserves in plants like sweet potatoes.