Download READING GUIDE: 17.1 – Genes and Variation (p. 482

WLHS / Biology / Monson
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READING GUIDE: 17.1 – Genes and Variation (p. 482-486)
1) Define the following terms:
● gene pool:
● allele frequency:
2) Complete the following description: “Evolution, in genetic terms, involves a
in a population over time.”
3) What are 3 sources of GENETIC VARIATION. Provide a brief description of each.
a.
b.
c.
4) What are single gene traits?
How many different phenotypes are possible with single gene traits?
5) What are polygenic traits?
How many different phenotypes are possible with polygenic traits?
6) Examine the graph in Figure 17.5. What does the shape of the graph indicate about height in
humans?
7) PREDICT: Suppose a dominant allele causes a plant disease that usually kills the plant before it can
reproduce. Over time, what would probably happen to the frequency of that dominant allele in the
population?
READING GUIDE: 17.2 – Evolution as Genetic Change in Populations (p. 487-492)
1) How does natural selection affect single-gene traits?
2) Compare: directional, stabilizing, and disruptive selection. Provide an example of each.
● DIRECTIONAL SELECTION:
example:
● STABILIZING SELECTION:
example:
● DISRUPTIVE SELECTION:
example:
3) Define GENETIC DRIFT:
4) How do the following lead to changes in a gene pool:
● BOTTLENECK EFFECT:
● FOUNDER EFFECT:
5) What is meant by “genetic equilibrium”?
6) What 5 conditions are necessary to maintain genetic equilibrium?
1.
4.
2.
5.
3.
7) Why is genetic equilibrium uncommon in actual populations in nature?
8) What is SEXUAL SELECTION?
Give 2 examples of sexual selection:
9) ANALYZING DATA: (see p. 491) Imagine that you know of a genetic condition
controlled by 2 alleles: R and r, which follow the rule of simple dominance at a
single locus. The condition affects only homozygous recessive individuals. (the
heterozygous phenotype shows no symptoms). The population you are studying
has a population size of 10,000 and there are 36 individuals affected by the
condition (q2 = 36 / 10,000 = 0.0036). Based on this information, use the
Hardy-Weinberg equations to answer the following questions:
1) What are the frequencies of the R and r alleles?
2) What are the frequencies of the genotypes: RR, Rr, and rr?
3) What percentage of people, in total, is likely to be carrying the “r” allele, whether or not they know it?
In a population of 10,000 people, how many people are “carriers” (Rr)?