Final answer:
Glycogen is the energy-storage polymer of glucose found in animals, stored mainly in liver and muscle cells, and is highly branched for efficient energy release.
Step-by-step explanation:
The polymer of glucose used as a vehicle to store energy reserves in animal cells is glycogen. Glycogen serves as an energy-storage polysaccharide in animals, with a highly branched structure enabling rapid hydrolysis when energy is needed. It is made up of glucose monomers and is stored primarily in liver and muscle cells. Unlike starch, a plant energy reserve, glycogen branches approximately every 10 to 15 glucose units, increasing its solubility in water and efficiency of energy release.