Which of the following would be used as energy in the human body source only after depletion of other sources glycogen in muscle cells calcium phosphate in bones glucose in the blood protein in mu?

Answer 1

glucose is the most efficient form of "food." Glucose would be used first. Protein in muscles will only be broken down in extreme starvation. As for the other answers, glucose is the energy source of choice and is the first to be broken down. Glycogen becomes the predominant energy source and glucose levels become depleted. Calcium phosphate cannot be used to generate ATPs in the body in any way.