Final answer:
The process requiring energy from food to help a cell maintain homeostasis is the phosphorylation of ADP to form ATP, as part of cellular respiration.
Step-by-step explanation:
The process that requires energy from food to help a cell maintain homeostasis is the addition of a phosphate ion to ADP to form ATP. This process, known as phosphorylation, involves pairing phosphates to ADP, requiring energy, and is a critical part of cellular respiration. Therefore, the correct answer to the question is B. a phosphate ion being added to ADP.
During cellular respiration, energy from the breakdown of food (like glucose) is used to convert ADP into ATP. In the presence of oxygen, oxidative phosphorylation, as part of the cellular respiration process, uses chemiosmosis to produce ATP in cells. This ATP can then be hydrolyzed (broken down) when energy is needed for various cellular processes, such as muscle contraction, nerve impulse transmission, and synthesis of biomolecules.