Question

D) Chidanans. E) nematodes. 10) Between organs and body wall, complex animals have a body cavity called a A) cnidarian. B) mesoderm. C) mesoglea. D) coelom. E) thorax. 4) In the animal kingdom, cephalization is A) development of a body that has paired structures forming a side-to-side mirror image. B) concentration of sensory structures in the head. C) the ability to respond rapidly to external stimuli. D) evolutionary development of a netlike system of veins. E) development of eyes at the anterior end of the organism. 11) Which germ layer gives rise to the muscle layer of the uterus? A) Ectoderm B) Mesoderm C) Endoderm 12) How many tissue layers are in the embryos of sponges? A) None B) One C) Two D) Three E) Four 5) One trend in the evolution of animals is the increase in the number of tissue layers during embryonic development. Flat-worms and more complex animals have_layers. A) two B) three C) four D) five E) six 13) An arthropod embryo has_germ layer(s). A) no B) one C) two D) three E) four 14) Anemones have no A) endoderm. B) mesoderm. C) ectoderm. 6) Organisms that are radially symmetrical have embryonic germ layers. A) two B) three C) four D) five E) six 7) The skin and nervous tissues develop from which germ layer? A) Ectoderm B) Endoderm C) Mesoderm D) Mesoglea E) Protoplasm 15) A cnidarian, which is radially symmetrical, has germ layer(s). A) no B) one c) two D) three E) four 8) Which of the following animal phyla is distinguished by a lack of tissues? A) Echinoderms B) Flatworms C) Annelids D) Roundworms E) Sponges 16) The common ancestor of sponges and other animals was probably A) unicellular. B) multicellular without tissues. C) multicellular with tissues but without organ systems. D) multicellular with tissues and a few organ systems. E) multicellular with tissues and many organ systems.

Answer 1

4. (B) Concentration of sensory organs in the head.

Cephalization is an evolutionary trend in which sense organs, mouth and nerves become concentrated and make head region.

5. (B) 3

Flatworms do have 3 tissue layers, which are ectoderm( which forms outer layer), mesoderm(covers internal organs) and endoderm(covers the digestive line)

6. (A) 2

Radially symmetrical animals are called diploblasts because they develop 2 germ layers- ectoderm and endoderm

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