38. The distinction between sponges and other animal phyla is based mainly on the absence versus the presence of
(A) a body cavity.
(B) a complete digestive tract.
(C) a circulatory system.
(D) true tissues.
(E) mesoderm.

34. Which of these statements about prokaryotes is correct? (A) Bacterial cells conjugate to mutually exchange genetic material. (B) Their genetic material is confined within a nuclear envelope. (C) They divide by binary fission, without mitosis or meiosis. (D) The persistence of bacteria throughout evolutionary time is due to their genetic homogeneity (i.e., sameness). (E) Genetic variation in bacteria is not known to occur, nor should it occur, because of their asexual mode of reproduction.

35. If all prokaryotes on Earth suddenly vanished, which of the following would be the most likely and most direct result? (A) The number of organisms on Earth would decrease by 10—20%. (B) Human populations would thrive in the absence of disease. (C) Bacteriophage numbers would dramatically increase. (D) The recycling of nutrients would be greatly reduced, at least initially. (E) There would be no more pathogens on Earth.

36. Which of the following is an ongoing trend in the evolution of land plants? (A) decrease in the size of the leaf (B) reduction of the gametophyte phase of the life cycle (C) elimination of sperm cells or sperm nuclei (D) increasing reliance on water to bring sperm and egg together (E) replacement of roots by rhizoids

37. Cephalization is primarily associated with (A) adaptation to dark environments. (B) method of reproduction. (C) fate of the blastopore. (D) type of digestive system. (E) bilateral symmetry.

39. What would be the most effective method of reducing the incidence of blood flukes in a human population? (A) Reduce the mosquito population. (B) Reduce the freshwater snail population. (C) Purify all drinking water. (D) Avoid contact with rodent droppings. (E) Carefully wash all raw fruits and vegetables.

40. Which of these is NOT considered an amniote? (A) amphibians (B) nonbird reptiles (C) birds (D) egg-laying mammals (E) placental mammals

41. Which of the following is true in plants? (A) Mitosis occurs in gametophytes to produce gametes. (B) Meiosis occurs in sporophytes to produce spores. (C) The gametophyte is within the flower in angiosperms. (D) A and B only (E) A, B, and C

42. We tend to think of plants as immobile when, in fact, they can move in many ways. All of the following are movements plants can accomplish EXCEPT (A) growth movements up or down in response to gravity. (B) folding and unfolding of leaves using muscle-like tissues. (C) growth movements toward or away from light. (D) changes in plant growth form in response to wind or touch. (E) rapid responses using action potentials similar to those found in the nervous tissue of animals.

43. Which of the following is NOT true about estuaries? (A) Estuaries are often bordered by mudflats and salt marshes. (B) Estuaries contain waters of varying salinity. (C) Estuaries support a variety of animal life that humans consume. (D) Estuaries usually contain no or few producers. (E) Estuaries support many semiaquatic species.

44. Carrying capacity is (A) seldom reached by marine producers and consumers because of the vast resources of the ocean. (B) the maximum population size that a particular environment can support. (C) fixed for most species over most of their range most of the time. (D) determined by density and dispersion data. (E) the term used to describe the stress a population undergoes due to limited resources.