Bio 198 Module 7 Study Questions and Correct Answers

What type of organism is considered ancestral to all animals? Protists What are the 4 characteristics are used to classify animals into groups? 1. Type of symmetry 2. Number of primary germ layers 3. Type of coelom 4. Presence/Absence of segmentation Asymmetry Definition No particular organization (Sponges) Radial Symmetry Definition Circularly organized , if you cut in half vertically you get two identical halves (Starfish) Bilateral symmetry Definition Left and right halves, only one cut directly down the middle will produce two equal halves (Goat) Dorsal Top Ventral Bottom Anterior Front Posterior Back Ectoderm Outer germ layer, skin/nervous tissue Mesoderm Middle germ layer, muscles/bones Endoderm Inner germ layer, Intestines/internal organs If an animal only has two primary germ layers, which is it missing? Mesoderm Coelom Definition Body cavity between organs and body wall Advantages of having a coelom 1. Internal organs held in place 2. Further complexity of organs 3. Independent movement of organs and body 4. Fluid protects internal environment