Question

1. Name two taxa of animals with coelomate body plans and closed circulatory system?

2. The dorso- ventrally flattened body plan of the playtyheminthesis is indicative of a gas exchange system that occurs how?

3. The vertebrate jaw first appeared as an evolutio of the anterior bony gill supports in what group of vertebrates?

4. what general group of vertebrate animals do not have a left and right artium chamber of the heart?

Answer 1

1. Vertebrates have a complete digestive system and a large coelom. Their circulatory system is closed, with respiratory pigments contained within blood vessels. Gas exchange is efficiently accomplished by gills, lungs, and in a few cases, moist skin.

2. Flatworms are small and flatworms which breathe through diffusion across the outer membrane. The flat shape of these organisms increases the surface area for diffusion, ensuring that each cell within the body is close to the outer membrane surface and has access to oxygen.

3. Jaws are homologous to the gill arches. In jawless fishes a series of gills opened behind the mouth, and these gills became supported by cartilaginous elements. The first set of these elements surrounded the mouth to form the jaw. The upper portion of the second embryonic arch supporting the gill became the hyomandibular bone of jawed fishes, which supports the skull and therefore links the jaw to the cranium. The hyomandibula is a set of bones found in the hyoid region in most fishes.

4. Amphibians has two atria and one ventricle.