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Lecture 1

BIOL 1202 Lecture Notes - Lecture 1: Gamete, Genotype Frequency, Stabilizing Selection


Department
Biological Sciences
Course Code
BIOL 1202
Professor
Pomarico
Lecture
1

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MASTERING BIOLOGY 23
1. Which of these individuals is a homozygous genotype?
a. AA
2. All the genes in a population are that population's _____.
a. Gene pool
3. Genetic drift is a process based on _____.
a. The role of chance
4. A mutation occurs when _____.
a. There is a change in the DNA sequence of a gene
5. Every few years a giant axe chops off the head of every person who is over 6 feet tall.
How will this affect the human population?
a. Alleles that promote “tallness” will decrease in frequency.
6. Modern travel along with migration reduces the probability of _____ having an effect on
the evolution of humans.
a. Genetic drift
7. The ease with which humans travel across the globe is likely to increase _____.
a. Gene flow
8. Homologous pairs of chromosomes are lined up independently of other such pairs during
_____.
a. Metaphase I
9. Crossing over, resulting in an increase in genetic variation, occurs between _____.
a. Nonsister chromatids of homologous chromosomes.
10. In human gamete production there is an average of _____ crossover events per
chromosome pair.
a. 2-3
11. Which of these gametes contain one or more recombinant chromosomes?
a. B, C, F, and G.
12. This animation illustrates _____ as it occurs during _____.
a. Crossing over… prophase I
13. Rabbit ear size tends to decrease as latitude increases. This is an example of _____.
a. A cline
14. If, on average, 46% of the loci in a species' gene pool are heterozygous, then the average
homozygosity of the species should be
a. 54%
15. Which variable is likely to undergo the largest change in value resulting from a mutation
that introduces a new allele into a population at a locus for which all individuals formerly
had been fully homozygous?
a. Average heterozygosity
16. Which statement about the beak size of finches on the island of Daphne Major during
prolonged drought is true?
a. Each bird’s survival was strongly influenced by the depth and strength of its
beak as the drought persisted.
17. Although each of the following has a better chance of influencing gene frequencies in
small populations than in large populations, which one most consistently requires a small
population as a precondition for its occurrence?
a. Genetic drift
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18. A trend toward the decrease in the size of plants on the slopes of mountains as altitudes
increase is an example of
a. A cline
19. Which statement about variation is true?
a. None of the above
20. Which of the following is a true statement concerning genetic variation?
a. It must be present in a population before evolution can occur in population.
21. Use the following information to answer the following question.
In those parts of equatorial Africa where the malaria parasite is most common, the sickle-
cell allele constitutes 20% of the β hemoglobin alleles in the human gene pool.
With respect to the sickle-cell allele, what should be true of the β hemoglobin locus in
U.S. populations of African-Americans whose ancestors were from equatorial Africa?
1. The average heterozygosity at this locus should be decreasing over time.
2. There is an increasing heterozygote advantage at this locus.
3. Diploidy is helping to preserve the sickle-cell allele at this locus.
4. Frequency-dependent selection is helping to preserve the sickle-cell allele at this locus.
a. 1 and 3
22. Blue light is a portion of the visible spectrum that penetrates deep into bodies of water.
Ultraviolet (UV) light, though, can penetrate even deeper. A gene within a population of
marine fish that inhabits depths from 500 m to 1,000 m has an allele for a photopigment
that is sensitive to UV light, and another allele for a photopigment that is sensitive to blue
light. 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?
a. B
23. A hypothetical population of 500 cats has two alleles, T and t, for a gene that codes for
tail length. (Tis completely dominant to t.) The table below presents the phenotype of cats
with each possible genotype, as well as the number of individuals in the population with
each genotype. Assume that this population is in Hardy-Weinberg equilibrium. Recall
that the Hardy-Weinberg equation is
24. p 2 + 2pq +q 2 = 1.
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a.
b.
25. A hypothetical population of 200 cats has two alleles, TL and TS, for a locus that codes for
tail length. The table below describes the phenotypes of cats with each possible genotype,
as well as the number of individuals in the population with each genotype. Which
statements about the population are true?
a.
b. heterozygotes make up 20& of the population
c. homozygous make up 80% of the population
d. in the entire cat population, 60% of the alleles are TS
e. in the entire cat population, the frequency of the TL allele is 0.4
f. assuming random mating, each gamete has a 40% chance of having a TL
allele and a 60% chance of having TS allele.
26. A hypothetical population of 300 wolves has two alleles, FB and FW, for a locus that
codes for fur color. The table below describes the phenotype of a wolf with each possible
genotype, as well as the number of individuals in the population with each genotype.
Which statements accurately describe the population of wolves?
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