Explain the difference between gills and lungs give examples of animals that only have lungs and animal that have both gills and lungs. What are the advantages of having gills, having lungs, and having both

carbohydrates are the body's preferred source of energy.

the principles and empirical processes of discovery and demonstration considered characteristic of or necessary for scientific investigation, generally involving the observation of phenomena, the formulation of a hypothesis concerning the phenomena, experimentation to test the hypothesis, and development of a conclusion that confirms, rejects, or modifies the hypothesis.