Hardy Weinberg Equilibrium Problems
Directions: Work the following problems on your own paper. Place your answers in the space provided on this worksheet. Staple the paper showing your work to this sheet to turn in. SHOW ALL WORK!!!
You may assume that all the following populations are in equilibrium to begin with. NO WORK, NO CREDIT, NO KIDDING!!!!
1. The frequency of two alleles in a gene pool is .1 (A) and .9 (a). What
is the:
a. frequency of the heterozygous individuals in the population?
b. frequency of the homozygous recessive individuals in the population?
2. Allele W, for white wool, is dominant to allele w for black wool. In a sample of 900 sheep,891 are white and 9 are black. Calculate the allelic frequencies for:
a. p
b. q
3. The frequency of the recessive homozygote genotype of a certain trait is .09. What is thepercentage of individuals homozygous for the dominant allele?
4. 36% of the individuals are recessive homozygotes for a certain trait. For the same trait, whatis the percentage in this population of:
a. homozygous dominant individuals?b. heterozygous individuals?
c. homozygous recessive individuals?
5. Allele T, for the ability to taste a particular chemical, is dominant to allele t, for the inability to taste it. At Cornell University, out of 400 surveyed students, 64 were found to benon-tasters. What is the percentage of heterozygous individuals?
6. In humans, Rh-positive individuals have the Rh antigen in their blood plasma while Rh-negative individuals do not. Assume that the Rh-positive phenotype is produced by a dominantgene Rh, and the Rh-negative phenotype is produced by its recessive allele rh. If 84% of the
individuals are Rh-positive, what are the frequencies of the:
a. Rh allele?
b. rh allele?
7. In corn, yellow kernel color is controlled by a dominant allele; white, by its recessive allele.A random sample of 1000 kernels from a population reveals that 910 are yellow and 90 are white.
What are the frequencies in this population of the:
a. yellow alleles?b. white alleles?
What is the percentage in this population of:
c. the heterozygotes?
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8. A rare disease, which is due to a recessive allele that is lethal when homozygous, occurswith a frequency of one in one million. How many individuals in a town of 14,000 can beexpected to carry this allele?
9. There are two alleles for a certain gene, A and a. The frequency of A is 80%. What percentage of the population will be heterozygous for this gene?
a. 4%b. 16%c. 32%d. 64%e. 100%
10. In a peppered moth population, the allele for light color is recessive and the allele fordark color is dominant. If there are 640 light moths, and 360 dark moths, how many of themoths are heterozygous?
a. 96%b. 64%c. 48%d. 32%e. 8%
11. Sickle-cell anemia is a disease caused by the inheritance of a dominant sickle gene. This gene is codominant with the normal hemoglobin gene. In a certain African tribe, 4% of the population is born with sickle-cell disease having inherited both dominant
sickle genes. What is the percentage of individuals in this tribe who enjoy the selective advantage of the sickle-cell gene (advantage through resistance to malaria) without all the symptoms of sickle-cell disease (heterozygotes)?
12. In the United States, approximately one child in 10,000 is born with PKU (phenylketonuria),a syndrome that affects individuals homozygous for the recessive allele. What is the frequency of:
a. the PKU allele in the population?
b. the normal allele?
What is the percentage of the population of:
c. carriers of this trait?
13. In a population of 200 mice, 98 are homozygous dominant for brown coat color (BB),84 are heterozygous (Bb), and 18 are homozygous recessive (bb). What are the frequencies for:
a. the alleles in this population?b. the genotypes of this population?
14. Two Siamese cats and 3 Persians survive a shipwreck and are carried on driftwood to a previously uninhabited tropical island. All five cats have normal ears, but one carries therecessive allele for folded ears (his genotype is Ff). What are the frequencies of allele F andallele f in the population of this island?
a. F = .8, f = .2b. F = .9, f = .1c. F = .1, f = .9
d. F = .2, f = .8 e. none of these
15. In the above problem, about how many cats would you expect to have folded ears whenthe island population reaches 20,000?
a. 0b. 20c. 200d. 1000e. 2000
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16. The allele frequencies in a population are A = 0.6, and a = 0.4. Predict the genotypicfrequencies for the next generation.
17. Suppose that one gene locus determines stripe pattern in skunks. SS skunks havetwo broad stripes; Ss skunks have two narrow stripes; ss skunks have white speckles down their backs. A sampling of a population of skunks found 65 broad-stripedskunks, 14 narrow-striped and 1 speckled. Determine the allele frequencies of:
a. p
b. q
18. In a population with 2 alleles for a particular locus, B and b, the allele frequencyof B is 0.7. What would be the frequency of heterozygotes?
19. In a population, 16% of the individuals show the recessive trait. What is thefrequency of the:
a. dominant allele?b. homozygous dominant genotype?
c. heterozygous genotype?
d. dominant phenotype?
20. Of the members of a population of pea plants, 9% are short (recessive). Whatare the frequencies of the:
a. recessive allele?b. dominant allele?
c. genotypes?
21. If p2= 0.36, what percentage of the population has the recessive phenotype?
22. 4% of the members of a population of pea plants are short (recessive). What arethe frequencies of the:
a. recessive allele?
b. dominant allele?
c. genotypes?
23. In Drosophila, the allele for normal length wings is dominant to the allele forvestigial wings. In a population of 1,000 individuals, 360 show the recessive phenotype. How many individuals would you expect to be:
a. homozygous dominant?b. heterozygous?
24. The allele for the ability to roll one's tongue is dominant to the allele for thelack of this ability. In a population of 500 individuals, 25% show the recessivephenotype. How many individuals would you expect to be:
a. homozygous dominant?
b. heterozygous?
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25. The allele for the hair pattern called "widow's peak" is dominant to the allelefor no widow's peak. In a population of 1,000 individuals, 510 show the dominantphenotype. How many individuals would you expect of the:
a. homozygous recessive genotype?b. homozygous dominant genotype?
c. heterozygous genotype?
BONUS FOR THE GIFTED.....
I. In white human beings, hair straightness of curliness is thought to be governed by a single pair of alleles showing incomplete (partial) dominance. Individuals with straight hair are homozygous for the S allele, while those with curly hair are homozygous for the C allele. Individuals with wavy hair are heterozygous. In a population of 1000 individuals, 245 were found to have straight hair, 393 had curly hair, and 362 had wavy hair.
a. Give the allelic frequencies of the S and C alleles.
b. Is this population in equilibrium?
II. In poultry, the autosomal gene FB produces black feather color and another allele, FW produces white feathers. The heterozygous condition produces blue Andalusian. A white hen is mated to a black rooster and the F2 were found to contain 78 black, 206 blue, and 116 white chickens.
a. What are the frequencies of the black and white alleles?
b. Is the population in equilibrium?
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