Compare the structure of adult mouse and frog skin. Mice have hair and sweat glands, frogs have mucous and poison glands, and there are other more subtle differences between the two. Compare the structure of adult mouse and frog lung. Frog lungs fill by positive pressure, mouse lungs fill by negative pressure. Mice have high oxygen requirements and frogs do not.
Frogs are carnivores, mice are herbivores.
Compare frog or mouse heart and skeletal muscle. Both muscle types are striated, but the heart beats continuously without tiring easily. LM, TEM 7. Compare frog small intestine before and after metamorphosis. Tadpoles have a diet very different from adults.