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Exam 25: Population Genetics

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Question 21

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By the early 1980s, the population of Florida panthers had dwindled to fewer than 30. Within this population, there was a high frequency of detrimental traits, including low sperm count and undescended testicles in males and kinked tails in both sexes. The future for this iconic population was bleak at best. Which of the following is the BEST solution that would both increase the likelihood that the population would survive and preserve the genetic identity of this unique population?

A) Genetic rescue, in which panthers from another population would be introduced in order to bring in new genetic variation and to reduce the genetic load.
B) The population could be removed and relocated to a better habitat, which should help the population recover.
C) Individuals with the genetic abnormalities could be removed from the population.
D) Some individuals could be moved so they will mate with specific other, healthier animals, which would assure more mixing of nondetrimental alleles.
E) There is no viable solution to saving this population.

F) All of the above
G) A) and E)

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Question 22

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Use Figure 25.3 to determine the BEST answers for the following question. - When a population is in Hardy-Weinberg equilibrium and p = 0.1 and q = 0.9, what are the approximate genotypic frequencies?

A) AA = 0.01, Aa = 0.18, aa = 0.81
B) AA = 0.81, Aa = 0.18, aa = 0.01
C) AA = 0.25, Aa = 0.5, aa = 0.25
D) AA = 0.2, Aa = 0.6, aa = 0.2
E) AA = 0.05, Aa = 0.4, aa = 0.55

F) B) and E)
G) B) and D)

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Question 23

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One way to define _____ is any change in allelic frequencies within a population.

_____ refers to the situation where the heterozygote has a lower fitness than both homozygotes (W₁₁ > W₁₂ < W₂₂) .

Human blood type is determined by three alleles I^A, I^B, and I^O. The alleles I^A and I^B are co-dominant to each other, and both are dominant to I^O. Within a large, randomly mating population (540,000 individuals) , the frequencies for the blood type alleles are 0.3 for the I^A allele, 0.6 for the I^O allele, and 0.1 for the I^B allele. Calculate the expected numbers of people in the population having each of the blood types A, B, AB, and O.

_____ is the product of sampling errors and chance events that may result in changes in allelic frequencies.

Suppose that in a population the frequency of a particular recessive condition is 1/400. Assume the presence of only a dominant allele (A) and a recessive allele (a) in the population and that the population is at Hardy-Weinberg equilibrium. What is the frequency of heterozygotes in the population?

A new kind of tulip is produced that develops only purple or pink flowers. Assume that flower color is controlled by a single-gene locus and that the purple allele (C) is dominant to the pink allele (c) . A random sample of 1000 tulips from a large cultivated field yields 847 purple flowers and 153 pink flowers. Estimate the proportion of all purple flowering plants that are heterozygotes and homozygotes.

If the relative fitness of the A¹A¹ genotype is 0.6, A¹A² is 1.0, and A²A² is 0.9, eventually the frequency of the A² allele will be:

A new kind of tulip is produced that develops only purple or pink flowers. Assume that flower color is controlled by a single-gene locus and that the purple allele (C) is dominant to the pink allele (c) . A random sample of 1000 tulips from a large cultivated field yields 847 purple flowers and 153 pink flowers. What is the frequency of the purple and pink alleles in this field population?

You discover a certain species of weed growing in soil contaminated with toxic PCBs and later determine that the PCB resistance is due to a single dominant allele. a. If 45% of the seeds from a randomly mating population of resistant weeds will germinate in contaminated soil, what is the frequency of the PCB-resistance allele? b. Among all the plants that germinate, what proportion will be heterozygous? c. What proportion will be homozygous dominant?

If a population is in Hardy-Weinberg equilibrium, the allelic and genotypic frequencies will not change. Prove the preceding statement for a pair of alleles in population X, which is in Hardy-Weinberg equilibrium.

Mutation has what effect on a population?

In overdominance, the HIGHEST fitness is found in which genotype?

Which of the following evolutionary forces does NOT normally change allelic frequencies?

Human blood type is determined by three alleles I^A, I^B, and I^O. The alleles I^A and I^B are co-dominant to each other, and both are dominant to I^O. Within a large, randomly mating population (540,000 individuals) , the frequencies for the blood type alleles are 0.3 for the I^A allele, 0.6 for the I^O allele, and 0.1 for the I^B allele. What percentage of the type B people are heterozygotes (I^BI^O) ?

Which agent of evolution tends to reduce genetic variation between populations and increase genetic variation within each population?

Genetic diseases in humans are usually rare and recessive. Why are the frequencies of alleles that cause rare, recessive diseases (or other recessive traits, for that matter) generally much higher than the frequency of the diseases (or traits) themselves?

The _____ measures the probability of alleles being identical by descent.

Genetic diseases in humans are usually rare and recessive. Why are the frequencies of alleles that cause rare, recessive diseases (or other recessive traits, for that matter) generally much higher than the frequency of the diseases (or traits) themselves?