Transcript Hardy-Weinberg Worksheet

Hardy-Weinberg Worksheet
• A population consists of 9% white sheep and
91% black sheep. What is the frequency of the
black-wool allele if the black-wool allele is
dominant and the white-wool allele is
recessive? Calculate your answer to the
nearest tenth.
q = 0.09 white sheep (homozygous recessives)
p2 + 2pq = 0.91 black sheep (homozygous dominants and heterozygotes)
Calculate the square root of 0.09 ….0.3 or 30%
p = 1-q = 0.7
• A blood group consists of two alleles, M and N.
The following data were obtained for a
population: Blood Number of
Types
M
MN
N
Individuals
169
182
49
Calculate the percentage of the M allele to the
nearest whole number.
Blood
Types
M
MN
N
Number of
Individuals
169
182
49
• Add all individuals to find population size: 169
+ 182 + 49 = 400
• p2 = 169/400 = 0.4225; p = 0.65
• In a certain population of birds, the allele for a
crown on the head (C) is dominant to the allele
for no crown on the head (c). A particularly cold
an d long winter favored the birds with no crown.
When spring came, researchers determined that
the population was currently in Hardy-Weinberg
equilibrium and that the occurance of the birds
with no crown was up to 24%. What will the
frequency of the no-crown allele be in 10 years?
Give your answer to the nearest hundredth.
0.49
24% = q2 therefore q=0.489
• A population of butterflies found in Madagascar
is polymorphic. There are two varieties of the
coloring. The trait for a yellow stripe on the wing
is dominant over having no stripe. In recent years
the island was struck by several powerful storms
and the butterfly population was drastically
reduced. Now the population is in HardyWeinberg equilibrium, and the trait for having no
stripe on the wing is 21% of the population. What
will the frequency of the allele for no stripe be
next year?
0.46
0.21 = q2 therefore q=0.46
• A population in Hardy-Weinberg equilibrium
consists of 300 sheep, some black and some
white. If the allele frequency for the recessive
allele is 0.3, how many black sheep are there
in the population?
Given that q=0.3 and p + q = 1, then p=0.7
The frequency of white individuals is q2 = (0.3)2 = 0.09
The frequency of black individuals must be 1-0.09 = 0.91 = p2 + 2pq
0.91 x 300 sheep = 273 sheep.
AP exam 1989
• Calculate, showing all work, the frequencies of
the alleles and the frequencies of the
genotypes in a population of 100,000 rabbits
of which 25,000 are white and 75,000 are
agouti. (In rabbits the white color is due to a
recessive allele, w, and the agouti is due to a
dominant allele, W.)
•
•
•
•
•
q2 = 25,000/100,000 = 0.25 therefore q=0.5
Since p + q = 1, p also equals 0.5
Homozygous dominant p2 = 0.25;
Homozygous recessive q2 = 0.25
Heterozygous dominant 2pq = 0.5
2008 B Exam
• For a particular genetic locus of a population,
the frequency of the recessive allele (a) is 0.4
and the frequency of the dominant allele is
0.6. What is the frequency of each genotype
(AA, Aa, aa) in this population? What is the
frequency of dominant phenotype?