Final answer:
Food must be converted to ATP, the energy currency of cells, through cellular respiration. This process enables the chemical energy stored in food to be used for work, thermal energy, and storage in fatty tissues depending on energy intake and physical activity.
Step-by-step explanation:
Energy Conversion in Cells. The energy from food must be converted into a form of energy that can be used by your cells, known as adenosine triphosphate or ATP. This conversion takes place through a process called cellular respiration. Initially, the sugars in the food are digested into glucose, which then undergoes cellular respiration to extract energy to produce ATP. ATP serves as the main energy currency for cellular functions, supporting activities from muscle contractions to active transport of molecules across cell membranes. Conservation of energy indicates that the chemical energy in food is not just used immediately but can also be stored as chemical energy in fatty tissue, or transformed into work and thermal energy. The overall energy conversion efficiency and where the energy is allocated depend on factors such as diet intake and physical activity levels.