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Exam 23: The Evolution of Populations

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Question 1

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Which of the following is a true statement concerning genetic variation?

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

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Question 2

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Which of the following is most likely to produce an African butterfly species in the wild whose members have one of two strikingly different colour patterns?

A) artificial selection
B) directional selection
C) stabilizing selection
D) disruptive selection
E) sexual selection

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D

Question 3

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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?

In the formula for determining a population's genotype frequencies, the 2 in the term 2pq is necessary because

If global warming permits mosquitoes to live at higher altitudes than they currently do, then in which direction should the entire plot in the correct distribution below be shifted? A. B. C. D.

You are maintaining a small population of fruit flies in the laboratory by transferring the flies to a new culture bottle after each generation. After several generations, you notice that the viability of the flies has decreased greatly. Recognizing that small population size is likely to be linked to decreased viability, the best way to reverse this trend is to

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.

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

Which statement about variation is true?

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?

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. The outcome of the conflict between bacteria and bacteriophage at any point in time results from

In the wild, male house finches (Carpodus mexicanus) vary considerably in the amount of red pigmentation in their head and throat feathers, with colours ranging from pale yellow to bright red. These colours come from carotenoid pigments that are found in the birds' diets; no vertebrates are known to synthesize carotenoid pigments. Thus, the brighter red the male's feathers are, the more successful he has been at acquiring the red carotenoid pigment by his food-gathering efforts (all other factors being equal) . During breeding season, one should expect female house finches to prefer to mate with males with the brightest red feathers. Which of the following is true of this situation?

There are 40 individuals in population 1, all with genotype A1A1, and there are 25 individuals in population 2, all with genotype A2A2. Assume that these populations are located far from each other and that their environmental conditions are very similar. Based on the information given here, the observed genetic variation is most likely an example of

Evolution

Which statement about the beak size of finches on the island of Daphne Major during prolonged drought is true?

Adult male humans generally have deeper voices than do adult female humans, which is the direct result of higher levels of testosterone causing growth of the larynx. If the fossil records of apes and humans alike show a trend toward decreasing larynx size in adult females and increasing larynx size in adult males, then

In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of the allele a is 0.3. What is the percentage of the population that is homozygous for this allele?

What is true of natural selection?

Use this information to answer the following questions Many species once roamed across large areas of continents, and for millions of years these species were "shaped" by their environment. Today, numerous species, especially large carnivores, are found in national parks and nature reserves that are isolated by hundreds or thousands of kilometres of land now occupied by humans. The cheetah is one example of a species that has shown several dramatic decreases in numbers over time, and now occupies a small fraction of its historic range. -Which of the following statements would most likely apply to cheetahs currently found in Kenya and South Africa?

If, on average, 46% of the loci in a species' gene pool are heterozygous, then the average homozygosity of the species should be