1. List all the adaptations that increase surface area in animal systems and explain why increased surface area improves the function of that system.
2. List all the counter current exchange systems used in animal systems and explain the adaptive advantage of each. (I already have kidneys and blood flow).
3. List all systems in which some component is based on conformational changes in protein (I already have endocrine, nervous, and immune. Would lymphatic count as separate from immune?)