| I: | Adult frog respires through lungs, skin and buccopharyngeal cavity. |
| II: | Cutaneous respiration is more effective during hibernation. |
| III: | Tadpoles respire only through lungs. |
| 1. | Columnar brush bordered epithelium |
| 2. | Ciliated epithelium |
| 3. | Squamous epithelium |
| 4. | Cuboidal brush bordered epithelium |