Download Unit 8 Hardy Weinberg Problem Set #2

HARDY-WEINBERG PROBLEMS
PROBLEM SET #2
1. After graduation, you and 19 of your closest friends (lets say 10 males and 10
females) charter a plane to go on a round-the-world tour. Unfortunately, you all
crash land (safely) on a deserted island. No one finds you and you start a new
population totally isolated from the rest of the world. Two of your friends carry (i.e.
are heterozygous for) the recessive cystic fibrosis allele (c). Assuming that the
frequency of this allele does not change as the population grows, what will be the
incidence of cystic fibrosis on your island?
2. Cystic fibrosis is a recessive condition that affects about 1 in 2,500 babies in the
Caucasian population of the United States. Please calculate the following.
A. The frequency of the recessive allele in the population.
B. The frequency of the dominant allele in the population.
C. The percentage of heterozygous individuals (carriers) in the population.
3. The ability to taste PTC is due to a single dominate allele "T". You sampled 215
individuals in biology, and determined that 150 could detect the bitter taste of PTC
and 65 could not. Calculate all of the potential frequencies.
4. In humans, Rh-positive individuals have the Rh antigen on their red blood cells,
while Rh-negative individuals do not. Assume that the Rh-positive phenotype is
produced by a dominant gene Rh, and the Rh-negative phenotype is produced by its
recessive allele rh. In a population that is in Hardy-Weinberg equilibrium, if 84
percent of the individuals are Rh-positive, what are the frequencies of the Rh allele
and the rh allele at this locus?
5. In white human beings, hair straightness or curliness is thought to be governed by a
single pair of allele showing partial dominance. Individuals with straight hair are
homozygous for the Is allele, while those with curly hair are homozygous for the Ic
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. Give the allelic frequencies of the Is and Ic alleles. Is this population in
Hardy-Weinberg equilibrium? Explain your answer and perform a chi-square test
to support your answer.
6. 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 was found to contain
78 black, 206 blue, and 116 white chickens. What are the frequencies of the black
and white alleles? Is this population in Hardy-Weinberg equilibrium? Explain,
using a chi-square test.
7. REAL WORLD APPLICATION PROBLEM
Choose a human trait to study and survey a population at your school. (Aim for at least
a sample size of 50 to get meaningful results). Use your sample to determine the allele
frequencies in the human population.
Traits (dominant listed first)
Hitchhiker's Thumb vs Straight Thumbs
Widow's peak vs straight hairline
Free earlobes vs attached earlobes
Tongue rolling vs non-rolling
Bent little fingers vs straight little fingers