Answer:
muscle cells in the legs of a marathon runner
Explanation:
Mitochondria are the powerhouse of cells and serve as a site for the aerobic stage of cellular respiration. Cellular respiration is complete oxidation of nutrients in the presence of oxygen to produce a large number of ATP molecules. Therefore, the cells that require more ATP molecules as an energy source would most likely have a greater number of mitochondria.
Muscle cells are responsible for body movement. Muscle cells in the legs of a runner would require a constant supply of ATP during running since muscle contraction requires ATP. To sustain the continuous muscle contraction during the marathon, the muscle cells in the legs of the runner would have most number of mitochondria.
