Biology- Chapter 23

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Biology- Chapter 23
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2014-11-10 20:47:25
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Principles of Biology- Chapter 23
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  1. During an individual organism's lifetime, which of these is most likely to help the organism respond properly to change in its environment?
    Change in gene expression
  2. If, on average, 46% of the loci in a species' gene pool are heterozygous, then the average homozygosity of the species should be
    54%
  3. Which of these variables is likely to undergo the largest change in value as the result of a mutation that introduces a brand-new allele into a population's gene pool at a locus that had formerly been fixed?
    Average heterozygosity
  4. Which statement about the beak size of finches on the island of Daphne Major during prolonged drought is true?
    Each bird's survival was strongly influenced by the depth and strength of its beak as the drought persisted
  5. Although each of the following has a better chance of influencing gene frequencies in small populations than in larger populations, which one most consistently requires a small population as a precondition for its occurrence?
    Genetic drift
  6. In modern terminology, diversity is understood to be a result of genetic variation. Which of the following is a recognized source of variation for evolution?
    Recombination by crossing over in meiosis
  7. A trend toward the decrease in the size of plants on the slopes of mountains as altitudes increase is an example of
    A cline
  8. The higher the proportion of loci that are "fixed" in a population, the lower is that population's
    Nucleotide variability and average heterozygosity only
  9. Which statement about variation is true?
    All new alleles are the result of nucleotide variability
  10. Rank the following one-base point mutations (from most likely to least likely) with respect to their likelihood of affecting the structure of the corresponding polypeptide:
    4,3,2,1
  11. The process that could have potentially contributed to the cluster's presence on more than one chromosome was
    Nondisjunction
  12. Which of the following is a true statement concerning genetic variation?
    It must be present in a population before natural selection can act upon the population
  13. Only one of these statements is true
    Four of these statements are true
  14. Whenever diploid populations are in Hardy- Weinberg equilibrium at a particular locus
    The allele's frequency should not change from one generation to the next, but its representation in homozygous and heterozygous genotypes may change
  15. In the formula for determining a population's genotype frequencies, the 2 in the term 2pq is necessary because
    Heterozygotes can come about in two ways
  16. In the formula for determining a population's genotype frequencies, the pq in the term 2pq is necessary because
    Heterozygotes have two alleles
  17. Hardy-Weinberg equilibrium must occur in populations wherein
    Only two of the responses above are correct
  18. In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of the allele a is 0.3. What is the percentage of the population that is homozygous for this allele?
    9.0
  19. In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of a is 0.2. What is the percentage of the population that is heterozygous for this allele?
    32.0
  20. In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is 0.1. What is the frequency of individuals with AA genotype?
    0.81
  21. You sample a population of butterflies and find that 56% are heterozygous at a particular locus. What should be the frequency of the recessive allele in this population?
    Allele frequency cannot be determined from this information
  22. Assuming Hardy-Weinberg equilibrium, what is the value of q for this population?
    0.80
  23. Evolution
    Can happen whenever any of the conditions for Hardy-Weinberg equilibrium are not met
  24. Over time, the movement of people on Earth has steadily increased. This has altered the course of human evolution by increasing
    Gene flow
  25. The production of new types of flu virus in the manner described above is most similar to the phenomenon of
    Gene flow
  26. If the original finches that had been blown over to the Galapagos from South America had already been genetically different from the parental populations of South American finches, even before adapting to the Galapagos, this would have been an example of
    both the first and third of these
  27. What is true of natural selection?
    Mutations occur at random; natural selection can preserve and distribute beneficial mutations
  28. The outcome of the conflict between bacteria and bacteriophage at any point in time results from
    Frequency-dependent selection
  29. Over the course of evolutionary time, what should occur?
    Methylated and nonmethylated strains should be maintained among both bacteria and bacteriophages, with ratios that vary over time
  30. Arrange the following from most general to most specific
    4,2,1,5,3
  31. Sexual dimorphism is most often a result of
    Intersexual selection
  32. During breeding season, one should expect female house finches to prefer to mate with males with the brightest red feathers. Which of the following is true of this situation?
    Three of the statements are correct
  33. During breeding season, one should expect female house finches to prefer to mate with males with the brightest
    Three of the responses are correct
  34. If the fossil records or apes and humans alike show a trend toward decreasing larynx size in adult females and increasing larynx size in adult males, then
    Sexual dimorphism was developing over time in these species
  35. If one excludes the involvement of gender in the situation, then the pattern that is apparent in the fossil record is most similar to one that should be expected from
    Disruptive selection
  36. Which of the following statements best summarizes evolution as it is viewed today?
    It is the differential survival and reproduction of the most-fit phenotypes
  37. Which of the following is most likely to produce an African butterfly species in the wild whose members have one of two strikingly different color patterns?
    Disruptive selection
  38. Most Swiss starlings produce four to five eggs in each clutch. Starlings producing fewer, or more, than this have reduced fitness. Which of the following terms best describes this situation?
    Stabilizing selection
  39. What maintains the presence of this harmful alleleĀ  in a population's gene pool?
    Diploidy
  40. Heterozygote advantage should be most closely linked to which of the following?
    Stabilizing selection
  41. If long-term climatic change resulted in all seeds becoming hard, what type of selection would then operate on the finch population?
    Directional selection
  42. This is most clearly an example of
    Frequency-dependent selection
  43. Which statement is supported by these observations?
    Phenotype is often the result of compromise
  44. The actual forelimbs of these mammals do not seem to be optimally arranged because
    Natural selection is generally limited to modifying structures that were present in previous generations and in previous species
  45. Which of these provides the best argument against this misconception?
    Advantageous alleles do not arise on demand
  46. Which of the following graphs best depicts the predicted distribution of these alleles within a population if the fish that carry these alleles prefer to locate themselves where they can see best?
    B
  47. Which of the following distributions is most likely, assuming little migration of people up or down the mountain?
    B
  48. If global warming permits mosquitoes to live at higher altitudes than they currently do, then in which direction should the entire plot in the correct distribution below be shifted?
    To the right
  49. What is true of the trait whose frequency distribution in a large population appears in the previous figure? It has probably undergone
    Stabilizing selection
  50. Which of the following is (are) probably occurring?
    2 and 3
  51. Which of the following represents the treatment option most likely to avoid the production of drug-resistant HIV (assuming no drug interactions or side effects)?
    Using moderate doses of NA and two different PIs at the same time for several months
  52. Within the body of an HIV-infected individual who is being treated with a single NA, and whose HIV particles are currently vulnerable to this NA, which of these situations can increase the virus' relative fitness?
    2 only
  53. If, for some reason, the two RNA molecules within a single HIV particle do not have identical sequences, then which of these terms can be applied due to the existence of the nonidentical regions?
    All but one of the responses are correct
  54. If two genes from one RNA molecule become detached and the, as a unit, get attached to one end of the other RNA molecule within a single HIV particle, which of these is true
    One of the RNA molecules has experienced gene duplication as the result of translocation
  55. Consequently, what should happen over the course of many generations?
    The proportions of both types of homozygote should decrease
  56. What is the most reasonable conclusion that can be drawn from the fact that the frequency of the recessive trait (aa) has not changed over time?
    The two phenotypes are about equally adaptive under laboratory conditions
  57. What is the estimated frequency of allele A in the gene pool?
    0.50
  58. What proportion of the population is probably heterozygous (Aa) for this trait?
    0.50
  59. In which population would it be least likely that an accident would significantly alter the frequency of the brown allele?
    Population B
  60. Which population is most likely to be subject to the bottleneck effect?
    Population A
  61. What should be the proportion of heterozygous individuals in populations that live here?
    0.32
  62. If the sickle-cell allele is recessive, what proportion of the population should be susceptible to sickle-cell anemia under typical conditions?
    0.04
  63. What should be happening to the sickle- cell allele in the United States, and what should be happening to it in equatorial Africa?
    Directional selection; stabilizing selection
  64. With the respect to the sickle-cell allele, what should be true of the B hemoglobin locus in US populations of African-Americans whose ancestors were from equatorial Africa?
    1 and 3
  65. What was primarily acting to change the frequency of the sickle-cell allele in the overall US population?
    Gene flow
  66. Thus, pleiotropic genes/alleles such as this can help explain why
    Adaptations are often compromises
  67. Which of these is closest to the allele frequency in the founding population?
    0.1 a, 0.9 A
  68. If one assumes that Hardy-Weinberg equilibrium applies to the population of colonists on this planet, about how many people will have attached earlobes when the planet's population reaches 10,000?
    100
  69. If four of the original colonists died before they produced offspring, the ratios of genotypes could be quite different in the subsequent generations. This would be an example of
    Genetic drift
  70. Recognizing that small population size is likely to be linked to decreased viability, the best way to reverse this trend is to
    Cross your flies with flies from another lab
  71. How should the frequency of the sickle-cell allele change in the remnant human population that survives above 6,000 feet, and which phenomenon accounts for this change in allele frequency?
    Decreases; bottleneck effect
  72. If the human flu virus contributes a gene for Tamiflu resistance (Tamiflu is an antiviral drug) to the new virus, and if the new virus is introduced to an environment lacking Tamiflu, then what is most likely to occur?
    If the Tamiflu-resistance gene involves a cost, it will experience directional selection leading to reduction in its frequency
  73. Natural selection changes allele frequencies because some ____ survive and reproduce more successfully than others
    Individuals
  74. No two people are genetically identical, except for identical twins. The main source of genetic variation among human individuals is
    The reshuffling of alleles in sexual reproduction
  75. Sparrows with average-sized wings survive severe storms better than those with longer or shorter wings, illustrating
    Stabilizing selection
  76. If the nucleotide variability of a locus equals 0%, what is the gene variability and number of alleles at that locus?
    Gene variability= 0%; number of alleles= 1
  77. Based on the information given here, the observed genetic variation is most likely an example of
    Genetic drift
  78. If the population is in Hardy-Weinberg equilibrium, what proportion of the flies carry both A1 and A2?
    0.42

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