32. Which of the following is NOT a shared characteristic of all chordates?
(A) dorsal, hollow nerve cord.
(B) notochord.
(C) post-anal tail.
(D) pharyngeal slits.
(E) four-chambered heart.

28. In a ___ distribution, many sample plots will contain few or no individuals while other plots will contain a large number. (A) clumped (B) regular (C) random (D) uniform (E) none of the above

29. Groups of plant or animal subpopulations which are spatially isolated but exchange individuals is called a (A) metapopulation. (B) community. (C) clumped distribution. (D) corridor. (E) none of the above.

30. Which of the following situations dose NOT increase species diversity in a community? (A) predation by keystone species. (B) habitat heterogeneity. (C) competitive exclusion. (D) moderate disturbances. (E) immigration of species.

31. Which ofthe following is an example ofMiillerian mimicry? (A) Two species of unpalatable butterfly that have the same color pattern. (B) A day-flying hawkmoth that looks like a wasp. (C) A katydid whose wings look like a dead leaf. (D) Two species of rattlesnake that both rattle their tails. (E) Two species of moths with wing spots that look like owl's eyes.

3 3. Natural selection is based on all of the following except (A) inheritance of acquired characteristics. (B) the fittest individuals leave the most offspring. (C) variation exists within populations. (D) populations tend to produce more individuals than the environment can support. (E) differential reproductive success within populations.

34. In which specific way does the founder effect lead to changes in gene frequency? (A) Small populations get large and then small again. (B) By chance alone, the descendants are not genetically representative of the ancestral population. (C) Involves homozygous ancestral populations that become heterozygous. (D) Natural selection acts as a principal cause of change in the process. (E) Depends on the importance of nonneutral mutations.

35. Reproduction isolation resulting from behavioral changes that inhibit mating between neighbors can lead to (A) hybrid vigor. (B) allopatric speciation. (C) sympatric speciation. (D) stabilizing selection. (E) directional selection.

36. Two islands that are similar in size and have the same distance from the mainland have very different species richness. According to the theory of island biogeography, the difference in species richness is probably due to (A) area effect. (B) distance effect. (C) habitat effect. (D) target effect. (E) rescue effect.

37. Wbich of the following is NOT true about estruaries? (A) Estuaries have lower net primary production than continentia} shelf. (B) Estuaries are susceptible to pollution and commercial developments by humans. (C) Estuaries support a variety of animal life that humans consume. (D) Estuaries are often bordered by mudflats and salt marshes. (E) Estuaries contain waters of varying salinity.

38. The perceived pitch of a sound depends on (A) vibrations of the tympanic membrane being transmitted through the incus. (B) vibrations of the oval window creating wave formation in the fluid of the vestibular canal. (C) the region of the basilar membrane where the signal originated. (D) A and C only. (E) A, B, and C.