Chapter 21 Flashcards
(23 cards)
In evolutionary terms, an organism’s fitness is measured by its _________.
A. stability in the face of environmental change
B. contribution to the gene pool of the next generation
C. genetic variability
D. mutation rate
E. health
B. contribution to the gene pool of the next generation
Evolution requires _________ in order to occur.
A. a large population
B. heritable variation
C. nonrandom, differential reproductive success
D. a long time
B. heritable variation
What is the ultimate source of new heritable variation in populations?
A. sexual reproduction (e.g., independent assortment, recombination, random mating)
B. gene flow (e.g., immigration/emigration)
C. selection (e.g., for favorable traits, against deleterious traits)
D. mutation (e.g., new alleles from errors in replication/recombination)
D. mutation (e.g., new alleles from errors in replication/recombination)
Which of the following is not an example of heritable genetic variation?
A. a protein translated incorrectly from an mRNA
B. a base-pair substitution in an exon
C. a 100-base-pair duplication in an intron
D. a 3-base-pair deletion in a promoter
A. a protein translated incorrectly from an mRNA
Below are listed genotypic frequencies for four populations at the
H locus. Which population(s), if any, are at Hardy-Weinberg
equilibrium at the H locus?
Population HH Hh hh
A. 0 1.0 0
B. 0.5 0 0.5
C. 0.33 0.33 0.33
D. 0.25 0.50 0.25
E. All of the above
D. 0.25 0.50 0.25
Below are listed genotypic frequencies for four populations at the
W locus. Which population(s), if any, are at Hardy-Weinberg
equilibrium at the W locus?
Population WW Ww ww
A. 0.81 0.18 0.01
B. 0.16 0.48 0.36
C. 0.49 0.42 0.09
D. 0.01 0.18 0.81
E. All of the above
E. All of the above
Consider this population that is not at Hardy-Weinberg equilibrium
at the H locus. How long should it take to reach equilibrium if
mating is random and all other H WE conditions are met?
Population HH Hh hh
0.5 0 0.5
A. one generation
B. two generations
C. several generations
D. insufficient information to determine
A. one generation
Red short-horned cattle are homozygous for the red allele, white cattle are homozygous for the white allele, and roan cattle are heterozygotes. Population A consists of 36% red, 16% white, and
48% roan cattle. What are the allele frequencies?
A. red = 0.36, white = 0.16
B. red = 0.6, white = 0.4
C. red = 0.5, white = 0.5
D. Allele frequencies cannot be determined unless the population is in equilibrium.
B. red = 0.6, white = 0.4
The frequency of cystic fibrosis, an autosomal recessive genetic disease, is 1 per 2,500 births among Northern Europeans. Assuming random mating in these populations, what is the frequency of cystic fibrosis alleles?
A. 1/2,500, or about 0.04%
B. 1/50, or about 2%
C. 1/25, or about 4%
D. The frequency cannot be calculated because selection violates Hardy-Weinberg assumptions.
C. 1/25, or about 4%
Until the 1950s, infants born with cystic fibrosis did not survive longer than a few months. If the frequency of carriers was 4% in the year 1900, what proportion of C F alleles was eliminated in one generation?
A. 100%
B. 50%
C. 4%
D. 2%
E. < 0.1%
D. 2%
Some moths on a tree are easier to see due to their lighter color and therefore are eaten by predators more often. At loci
controlling moth color, which of the Hardy-Weinberg conditions is not being met?
A. large population size
B. no mutation
C. no gene flow
D. random mating occurring
E. no selection
E. no selection
Female sailfin blennies (a fish) tend to choose males with either a large sailfin on top of their heads or the best flicking motion of their sailfin. At loci controlling sailfins, which of the Hardy-Weinberg conditions is not being met?
A. large population size
B. no mutation
C. no gene flow
D. random mating occurring
E. no selection
D. random mating occurring
Due to global warming, a river has dried up, allowing two different rabbit populations, which were isolated before, to mate with one another. Which of the Hardy-Weinberg criteria may not be met due to this?
A. large population size
B. no mutation
C. no gene flow
D. random mating occurring
E. no selection
C. no gene flow
If a locus is at Hardy-Weinberg equilibrium, which of the following statements are true?
A. The population is not evolving.
B. The population is not evolving at that locus.
C. The population is not experiencing gene flow.
D. The population is mating randomly.
E. All of the above.
B. The population is not evolving at that locus.
The textbook discusses how the conversion of quality habitat into farmland has greatly depleted the greater prairie chicken populations and, as a result, their genetic diversity. Which of the following occurred in this example?
A. founder effects
B. mutation
C. natural selection
D. gene flow
E. bottleneck
E. bottleneck
Among rock pocket mice that live on volcanic substrates, brown mice are preyed upon more than black mice. This is an example of what type of selection?
A. directional selection
B. disruptive selection
C. stabilizing selection
A. directional selection
During a drought, it was discovered that finches with large beaks and those with small beaks were more successful than those with intermediate beaks due to the food sources available. This is an example of what type of selection?
A. directional selection
B. disruptive selection
C. stabilizing selection
B. disruptive selection
In humans, very low birth weight results in increased mortality, and very high birth weight leads to complications with delivery. This is an example of what type of selection?
A. directional selection
B. disruptive selection
C. stabilizing selection
C. stabilizing selection
A high proportion of the cats on Key West have extra toes (polydactyly). What is the most likely explanation?
A. high rate of mutation
B. founder effect
C. bottleneck effect
D. directional selection for extra toes
B. founder effect
If a trait is being selected for in a population, what forces could possibly counteract that selection?
A. genetic drift
B. gene flow
C. mutation
D. all of the above
E. none of the above
D. all of the above
Which of the following can introduce new genetic variation into a population?
A. selection
B. gene flow
C. mutation
D. A, B and C
E. B and C
E. B and C
If a population is experiencing strong genetic drift, what might result from that?
A. loss of genetic variation
B. increased genetic variation
C. mutation
D. selection
E. gene flow
A. loss of genetic variation
In some regions where malaria is endemic, the frequency of the sickle-
cell allele is maintained as high as 10% due to heterozygous advantage. If modern technology were to completely eradicate malaria but not alleviate sickle-cell disease, what would be expected to happen to the sickle-cell allele frequency in subsequent generations?
A. remain near 10%
B. gradually drop toward zero
C. drop slightly, then restabilize
D. rise slightly, then restabilize
B. gradually drop toward zero
