1. Homeostasis is often maintained by feedback loops that involve A. gastrulation.

1. 1. Homeostasis is often maintained by feedback loops that involve • A. gastrulation. • B. feedback inhibition. • C. spontaneous generation. • D. equilibrium.

2. 2. Animals respond to events in their environments using specialized cells called • A. muscle cells. • B. nerve cells. • C. gametes. • D. blood cells.

3. 3. A characteristic that all animals share is being • A. heterotrophic. • B. autotrophic. • C. prokaryotic. • D. anaerobic.

4. 4. Excretion is a function of all animals that involves • A. exchange of oxygen and carbon dioxide. • B. transport of material from one part of the body to another. • C. digestion and absorption of food molecules. • D. removal of metabolic wastes.

5. 5. One major trend in animal evolution has been • A. the simplification of body organ systems. • B. an increase in the degree of cephalization. • C. a shift from bilateral symmetry to radial symmetry. • D. disappearance of the blastula stage in early development.

6. 6. In sponges, a spike-shaped structure made of chalklike calcium carbonate or glasslike silica is a(an) • A. spicule. • B. archaeocyte. • C. choanocyte. • D. epidermal cell.

7. 7. An immature stage of an organism that looks different from the adult form is a(an) • A. gemmule. • B. larva. • C. archaeocyte. • D. choanocyte.

8. 8. Specialized cells that use flagella to move water through the sponge are • A. gemmules. • B. pores. • C. spicules. • D. choanocytes.

9. 9. Sponges are • A. detritivores. • B. carnivores. • C. filter feeders. • D. herbivores.

10. 10. Sponges can reproduce • A. sexually only. • B. asexually only. • C. both sexually and asexually. • D. by metamorphosis.

11. 11. The characteristic that defines the cnidarians is • A. bilateral symmetry. • B. stinging cells. • C. a gastrovascular cavity. • D. cephalization.

12. 12. Which of the following statements is generally true of polyps and medusas? • A. Polyps are sessile, and medusas are motile. • B. Polyps are motile, and medusas are sessile. • C. Both polyps and medusas are sessile. • D. Both polyps and medusas are motile.

13. 13. During the life cycle of Aurelia, the zygote grows into a free-swimming • A. polyp. • B. larva. • C. medusa. • D. gemmule.

14. 14. Cnidarians, such as the sea anemone, move using • A. water currents. • B. an exoskeleton. • C. a hydrostatic skeleton. • D. an endoskeleton.

15. 15. Groups of sensory cells that help cnidarians determine the direction of gravity are known as • A. nerve nets. • B. statocysts. • C. ocelli. • D. cnidocytes.

16. 16. Flatworms are the simplest animals to have • A. two germ layers. • B. bilateral symmetry. • C. radial symmetry. • D. two openings in the digestive system.

17. 17. An individual that has both male and female reproductive organs is known as a • A. turbellarian. • B. proglottid. • C. hermaphrodite. • D. parasite.

18. 18. The function of flame cells in flatworms is to • A. digest food and move it to various parts of the body. • B. detect the presence of chemicals in the surroundings. • C. remove excess water and metabolic wastes. • D. move reproductive cells into position for fertilization.

19. 19. A flatworm that lacks a digestive tract is the • A. planarian. • B. free-living flatworm. • C. tapeworm. • D. fluke.

20. 20. Turbellarians (Planarians) differ from most other flatworms because they • A. live freely on land. • B. live freely in fresh and salt water. • C. are marine parasites. • D. are land-dwelling parasites.

21. 21. In roundworms, the body cavity that forms between the endoderm and mesoderm is the • A. ganglion. • B. hydrostatic skeleton. • C. pseudocoelom. • D. coelom.

22. 22. All of the following are parasitic roundworms EXCEPT • A. tapeworms • B. filarial worms • C. hookworms • D. ascarid worms

23. 23. Characteristics of roundworms include a digestive system with • A. one opening and a pseudocoelom. • B. one opening but no pseudocoelom. • C. two openings and a pseudocoelom. • D. two openings but no pseudocoelom.

24. 24. Gas exchange and excretion of metabolic wastes in roundworms occurs • via a complex system of alveoli. • through their body walls. • C. through excretory tubules. • D. by flame cells.

25. 25. The roundworms called ascarids cause harm by • A. causing serious body swelling. • B. burrowing into body tissues and causing pain. • C. causing malnutrition. • D. causing weakness and poor growth.

26. 26. In the earthworm, food is absorbed in an organ called the • A. intestine. • B. crop. • C. gizzard. • D. clitellum.

27. 27. Annelids differ from other worm phyla because they have • A. segmented bodies and a true coelom. • B. unsegmented bodies and a pseudocoelom. • C. mesoderm and one opening in the digestive system. • D. segmented bodies and one opening in the digestive system.

28. 28. How many major blood vessels does an earthworm have? • A. one • B. two • C. three • D. none

29. 29. Ecologically, one of the most beneficial functions of an earthworm is to • A. providing food and habitats for tropical fish. • B. sucking the blood of living animals. • C. aerating and fertilizing the soil. • D. killing pest insects that inhabit the soil.

30. 30. In an earthworm, the thickened bank of specialized segments used in reproduction (secretes cocoon) is the • A. nephridia. • B. gizzard. • C. clitellum. • D. seta.

31. 31. The trochophore larva is a characteristic that mollusks share with • A. flatworms. • B. roundworms. • C. annelids. • D. flukes.

32. 32. Water enters and leaves the body of a bivalve through • A. a siphon. • B. cilia. • C. a coelom. • D. a nephridium.

33. 33. The most active group of mollusks is the • A. gastropods. • B. bivalves. • C. cephalopods. • D. shell-less gastropods.

34. 34. Unlike the other mollusks, cephalopods have a(an) • A. closed circulatory system. • B. ventral blood vessel. • C. open circulatory system. • D. dorsal blood vessel.

35. 35. The body plan of almost all mollusks includes all of the following EXCEPT a • A. foot. • B. mantle. • C. shell. • D. radula.

36. 36. The mouthparts of arthropods are • A. similar in all species. • B. adapted to enable different species to eat different foods. • C. adapted to enable different species to respire in different ways. • D. useful for locomotion as well as feeding.

37. 37. Arthropods have open circulatory systems, which means that blood • A. leaves the blood vessels, flows through sinuses, and then returns to the heart. • B. flows from the heart directly into sinuses and then returns to the heart. • C. never leaves the circulatory system. • D. vessels open to the external environment.

38. 38. Characteristics which define the arthropods include • A. an endoskeleton made of chitin and jointed appendages. • B. an endoskeleton made of chitin and six pairs of appendages. • C. an exoskeleton made of chitin and jointed appendages. • D. an exoskeleton made of chitin and Malpighian tubules.

39. 39. What type(s) of fertilization do terrestrial arthropods have? • A. internal • B. external • C. both internal and external • D. hermaphroditic

40. 40. What happens to the exoskeleton of an arthropod as the animal grows? • A. It remains soft until the animal reaches adulthood. • B. It develops additional body segments. • C. It softens and stretches to a larger size. • D. It is discarded and replaced by a new, larger exoskeleton.

41. 41. The two main groups of chelicerates are • A. spiders and scorpions. • B. horseshoe crabs and spiders. • C. horseshoe crabs and arachnids. • D. arachnids and insects.

42. 42. Insects are part of the group • A. crustaceans. • B. uniramians. • C. chelicerates. • D. diplopods.

43. 43. Most mites and ticks are • A. parasites. • B. predators. • C. herbivores. • D. detritivores.

44. 44. Which of the following is NOT a typical crustacean characteristic? • A. either two or three body segments • B. chewing mouthparts called mandibles • C. chelicerae that paralyze prey • D. two pairs of antennae

45. 45. Spiders are considered arachnids because they have • A. two major body segments and six legs. • B. three major body segments and eight legs. • C. two major body segments and eight legs. • D. three major body segments and six legs.

46. 46. How many body parts do insects have? • A. two • B. three • C. four • D. five

47. 47. Which group contains the most species? A. vertebrates B. nonvertebrate invertebrates C. noninsect arthropods D. insects

48. 48. Characteristics shared by typical insects include • A. six walking legs and one pair of wings. • B. six walking legs and two pairs of wings. • C. eight walking legs and one pair of wings. • D. eight walking legs and two pairs of wings.

49. 49. The immature form of an insect that undergoes incomplete metamorphosis is called a(n) • A. larva. • B. nymph. • C. pupa. • D. embryo.

50. 50. Which of the following species form complex societies? • A. butterflies • B. ants • C. locusts • D. flies