___24. In which population is the frequency of the allele for brown feathers highest? a. A b. B c. C d. D e. E ____25. In which population would it be least likely that an accident would significantly alter the frequency of the brown allele? a. A b. B c. C d. D e. E ____26. The probability of a mutation at a particular gene locus is ____, and the probability of a mutation in the genome of a particular individual is ____. a. high; low b. low; high c. low; low d. high; high e. moderate; moderate ____27.
Which factor is the most important in producing the variability that occurs in each generation of humans? a. mutation b. sexual recombination c. genetic drift d. nonrandom mating e. natural selection ____28. In a large, sexually reproducing population, the frequency of an allele changes from 0. 6 to 0. 2. From this change, one can most logically assume that, in this environment, a. the allele is neutral. b. the allele mutates readily. c. random processes have changed allelic frequencies. d. there is no sexual selection. e. the allele reduces fitness. ____29.
You are maintaining a small population of fruit flies in the laboratory by transferring the flies to a new culture bottle after each generation. After several generations, you notice that the viability of the flies has decreased greatly. Recognizing that small population size is likely to be linked to decreased viability, the best way to reverse this trend is to a. cross your flies with flies from another lab. b. reduce the number of flies that you transfer at each generation. c. transfer only the largest flies. d. change the temperature at which you rear the flies. e. hock the flies with a brief treatment of heat or cold to make them more hardy. ____30. If the frequency of a particular allele that is present in a small, isolated population of alpine plants should change due to a landslide that leaves an even smaller remnant of surviving plants, then what has occurred? a. a bottleneck b. genetic drift c. microevolution d. A and B only e. A, B, and C ____31. Through time, the movement of people on Earth has steadily increased. This has altered the course of human evolution by increasing a. nonrandom reproduction. b. geographic isolation. c. enetic drift. d. mutations. e. gene flow. ____32. Gene flow is a concept best used to describe an exchange between a. species. b. males and females. c. populations. d. individuals. e. chromosomes. Use the information below to answer the following questions. In the year 2500, five male space colonists and five female space colonists (all unrelated to each other) settle on an uninhabited Earthlike planet in the Andromeda galaxy. The colonists and their offspring randomly mate for generations. All ten of the original colonists had free earlobes, and two were heterozygous for that trait.
The allele for free earlobes is dominant to the allele for attached earlobes. ____33. If four of the original colonists died before they produced offspring, the ratios of genotypes could be quite different in the subsequent generations. This is an example of a. diploidy. b. gene flow. c. genetic drift. d. disruptive selection. e. stabilizing selection. ____34. The higher the proportion of loci that are “fixed” in a population, the lower is that population’s a. nucleotide variability. b. genetic polymorphism. c. average heterozygosity. d. A, B, and C e. A and B only
Choose among these options to answer the following questions. Each option may be used once, more than once, or not at all. A. random selection B. directional selection C.
Male satin bowerbirds adorn structures that they build, called “bowers,” with parrot feathers, flowers, and other bizarre ornaments in order to attract females. Females inspect the bowers and, if suitably impressed, allow males to mate with them, after which they go off to nest by themselves. The evolution of this behavior is best described as due to a. survival of the fittest. b. artificial selection. c. sexual selection. d. natural selection. e. disruptive selection. ____40. In many animal species, mature males are much larger than mature females. This size difference can be attributed to a. ale hormones having a more positive effect on body size than female hormones do. b. the operation of intrasexual selection. c. females preferentially selecting larger males as mates. d. A and B only e. A, B, and C ____41. Adult male vervet monkeys have red penises and blue scrotums. Males use their colorful genitalia in dominance displays wherein they compete with each other for access to females. The coloration of the male genitalia is best explained as the result of ____, and specifically of ____. a. natural selection; stabilizing selection b. disruptive selection; intrasexual selection . sexual selection; intrasexual selection d. natural selection; intersexual selection e. sexual selection; disruptive selection ____42. When imbalances occur in the sex ratio of sexual species that have two sexes (i. e. , other than a 50:50 ratio), the members of the minority sex often receive a greater proportion of care and resources from parents than do the offspring of the majority sex. This is most clearly an example of a. sexual selection. b. disruptive selection. c. balancing selection. d. stabilizing selection. e. frequency-dependent selection. ____43.
Which of the following statements about species, as defined by the biological species concept, is (are) correct? I. Biological species are defined by reproductive isolation. II. Biological species are the model used for grouping extinct forms of life. III. The biological species is the largest unit of population in which successful reproduction is possible. a. I only b. II only c. I and III d. II and III e. I, II, and III ____44. Which of the following is not considered an intrinsic isolating mechanism? a. sterile offspring b. ecological isolation c. geographic isolation . gametic incompatibility e. timing of courtship display ____45. Dog breeders maintain the purity of breeds by keeping dogs of different breeds apart when they are fertile. This kind of isolation is most similar to which of the following reproductive isolating mechanisms? a. reduced hybrid fertility b. hybrid breakdown c. mechanical isolation d. habitat isolation e. gametic isolation ____46. Two species of frogs belonging to the same genus occasionally mate, but the offspring do not complete development. What is the mechanism for keeping the two frog species separate? a. he postzygotic barrier called hybrid inviability b. the postzygotic barrier called hybrid breakdown c. the prezygotic barrier called hybrid sterility d. gametic isolation e. adaptation ____47. A defining characteristic of allopatric speciation is a. the appearance of new species in the midst of old ones. b. asexually reproducing populations. c. geographic isolation. d. artificial selection. e. large populations. ____48. According to the concept of punctuated equilibrium, the “sudden” appearance of a new species in the fossil record means that a. the species is now extinct. b. peciation occurred instantaneously. c. speciation occurred in one generation. d. speciation occurred rapidly in geologic time. e. the species will consequently have a relatively short existence, compared with other species. ____49. Which of the following would be a position held by an adherent of the punctuated equilibrium theory? a. A new species forms most of its unique features as it comes into existence and then changes little for the duration of its existence. b. One should expect to find many transitional fossils left by organisms in the process of forming new species. . Given enough time, most existing species will gradually evolve into new species. d. Natural selection is unimportant as a mechanism of evolution. e. Most speciation is anagenetic. ____50. Which of the following statements about speciation is correct? a. The goal of natural selection is speciation. b. When reunited, two allopatric populations will not interbreed. c. Natural selection chooses the reproductive barriers for populations. d. Prezygotic reproductive barriers usually evolve before postzygotic barriers. e. Speciation is included within the concept of macroevolution.