Download Directed Reading 17.2 - Blair Community Schools

Name ______________________________ Class ___________________ Date __________________
Skills Worksheet
Directed Reading 17.2
Section: Genetic Change
In the space provided, write the letter of the description that best matches each term.
_____ 1. genetic equilibrium a. the movement of alleles into and out of a
population
_____ 2. gene flow
b. one of the most powerful agents of genetic
change
_____ 3. nonrandom mating c. eliminates individuals with average phenotype
values
_____ 4. genetic drift
d. a change in allele frequency because of
random occurrences
_____ 5. mutation
e. the state of a population in which no genetic
change occurs
_____ 6. natural selection
f. the mechanism that drives evolution
_____ 7. stabilizing selection g. individuals show preferences in the choice of
breeding partners
_____ 8. disruptive selection h. eliminates individuals that have alleles for any
extreme type
In the space provided, explain how the terms in each pair are related to each other.
9. gene flow, genetic drift
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10. mutation, natural selection
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11. directional selection, stabilizing selection
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Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Biology
3
Population Genetics and Speciation
Name ______________________________ Class ___________________ Date __________________
Directed Reading continued
Read each question, and write your answer in the space provided.
12. What are the five forces of genetic change?
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13. What does the Hardy-Weinberg principle predict?
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14. Explain why natural selection does not act directly on genes.
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15. Explain how sexual reproduction affects evolution.
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16. What effect does nonrandom mating have on the frequency of alleles in a
population?
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17. Explain how natural selection is limited.
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18. Describe directional selection and give an example.
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19. Describe stabilizing selection.
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20. What is disruptive selection?
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Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Biology
4
Population Genetics and Speciation