Final answer:
Fatty acids produce more ATP compared to glucose due to their higher energy density and more reduced form. Animals use fats for long-term energy storage.
Step-by-step explanation:
When comparing the amount of energy extracted (ATP produced) from glycerol and fatty acids to glucose, the fatty acids produce significantly more ATP. For example, stearic acid produces 120 ATP molecules, which is significantly higher than the 32 ATP molecules produced by glucose. The higher ATP yield from fatty acids is due to their higher energy density and the fact that they are in a more reduced form than glycogen. Animals use fats as a relatively longer-term energy storage, while glucose serves as a quick energy source.