Which cellular process involves the conversion of stored food reserves into useful energy for the plant?

The correct answer is respiration. This cellular process is vital for plants as it involves breaking down stored food reserves, such as carbohydrates, to release useful energy. During respiration, glucose produced during photosynthesis is converted into adenosine triphosphate (ATP), which is the energy currency of cells. This energy is essential for various physiological processes within the plant, including growth, repair, and maintenance of cellular functions.

In contrast, photosynthesis is the process through which plants convert light energy, usually from the sun, into chemical energy stored in glucose. While it is crucial for creating food, it is not the process that breaks down those food reserves to release energy. Transpiration refers to the loss of water vapor from plant parts, primarily leaves, and while it plays a role in water regulation and nutrient transport, it does not directly involve energy release. Hydration involves the absorption of water, which is necessary for life but does not pertain to the conversion of food reserves into energy. Thus, respiration is key for energy production from stored food in plants.