Chapter 23

1) During an individual organism's lifetime, which of these is most likely to help the organism respond properly to changes in its environment? A) change in gene expression B) change in allele or gene frequency C) microevolution D) change in average heterozygosity

A

10) Which population is most likely to be subject to the bottleneck effect? A) population A B) population B C) population C D) They are all equally likely. E) It is impossible to tell from the information given

A

12) No two people are genetically identical, except for identical twins. The main source of genetic variation among human individuals is A) the reshuffling of alleles in sexual reproduction. B) geographic variation within the population. C) environmental effects. D) genetic drift due to the small size of the population. E) new mutations that occurred in the preceding generation.

A

3) Which of the following is a true statement concerning genetic variation? A) It must be present in a population before natural selection can act upon the population. B) It is created by the direct action of natural selection. C) It tends to be reduced by the processes involved when diploid organisms produce gametes. D) It arises in response to changes in the environment. E) A population that has a higher average heterozygosity has less genetic variation than one with a lower average heterozygosity.

A

4) The restriction enzymes of bacteria protect the bacteria from successful attack by bacteriophages, whose genomes can be degraded by the restriction enzymes. The bacterial genomes are not vulnerable to these restriction enzymes because bacterial DNA is methylated. This situation selects for bacteriophages whose genomes are also methylated. As new strains of resistant bacteriophages become more prevalent, this in turn selects for bacteria whose genomes are not methylated and whose restriction enzymes instead degrade methylated DNA. Over the course of evolutionary time, what should occur? A) Methylated and nonmethylated strains should be maintained among both bacteria and bacteriophages, with ratios that vary over time. B) Methylated DNA should become fixed in the gene pools of bacterial species. C) Nonmethylated DNA should become fixed in the gene pools of bacteriophages. D) Methylated DNA should become fixed in the gene pools of bacteriophages. E) Both the first and second responses are correct.

A

2) 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? A) mistakes in translation of structural genes B) recombination by crossing over in meiosis C) rampant changes to the dictionary of the genetic code D) mistakes in protein folding E) binary fission

B

9) In which population would it be least likely that an accident would significantly alter the frequency of the brown allele? A) population A B) population B C) population C D) They are all the same. E) It is impossible to tell from the information given.

B

Arrange the following from most general (i.e., most inclusive) to most specific (i.e., least inclusive): 1 natural selection 2. microevolution 3. intrasexual selection 4. evolution 5. sexual selection A) 1, 2, 4, 5, 3 B) 4, 2, 1, 5, 3 C) 4, 2, 1, 3, 5 D) 1, 4, 2, 5, 3 E) 4, 1, 2, 3, 5

B

6) Which of the following statements best summarizes evolution as it is viewed today? A) It is the descent of humans from the present-day great apes. B) It represents the result of selection for acquired characteristics. C) It is the differential survival and reproduction of the most-fit phenotypes. D) It is synonymous with the process of gene flow

C

8) Considering the overall human population of the U.S. mainland at the time when the slave trade brought large numbers of people from equatorial Africa, what was primarily acting to change the frequency of the sickle-cell allele in the overall U.S. population? A) genetic drift B) natural selection C) gene flow D) founder effect E) Two of the responses are correct.

C

7) There are those who claim that the theory of evolution cannot be true because the apes, which are supposed to be closely related to humans, do not likewise share the same large brains, capacity for complicated speech, and tool-making capability. They reason that if these features are generally beneficial, then the apes should have evolved them as well. Which of these provides the best argument against this misconception? A) A population's evolution is limited by historical constraints. B) Evolution can be influenced by environmental change. C) Adaptations are often compromises. D) Advantageous alleles do not arise on demand.

D

11) The volcano is currently dormant, but in a hypothetical future scenario, satellite cones at the base of Mt. Kilimanjaro spew sulfurous gases and lava, destroying all life located between the base and 6,000 feet above sea level. As a result of this catastrophe, 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? A) decreases; gene flow B) increases; genetic drift C) increases; nonrandom mating D) decreases; disruptive selection E) decreases; bottleneck effect

E