GENETICS EXAM 3 QUESTIONS
AND THEIR COMPLETE SOLUTIONS
Phenyketonuria is an inborn error of metabolism
caused by an autosomal recessive gene. The
frequency of this allele in the population is 0.03.
Assuming Hardy-Weinberg equilibrium, what is the
expected incidence of phenyketonuria among the
offspring of all matings in which both parents are
found to be carriers?
A. 0.0009
B. 0.03
C. 0.25
D. 0.5
C
The MN blood group phenotypes of 2,000 British
citizens were 596M, 978MN, and 426N. What is the
frequency of the NN genotype?
A. 0.106
B. 0.149
C. 0.457
D. 0.213
E. 0.915
D
What factor could cause the allelic frequencies of a
gene to shift randomly within a population?
,A. Genetic drift
B. High mutation rate
C. Assortative mating
D. Migration
E. Natural selection
A
Selection for or against a recessive allele in diploids is
inefficient when
A. the recessive allele is rare.
B. the recessive allele is frequent.
C. the frequencies of the recessive allele in males and
females are different.
D. the population is not in Hardy-Weinberg
equilibrium.
A
Which of the following processes does not contribute
to changing allele frequencies in populations?
A. mutation
B. inbreeding
C. migration
D. natural selection
E. genetic drift
B
A trait due to a recessive X-linked allele in a large,
randomly mating population affects one male in ten.
What is the frequency of affected females?
A. 1 in 10
, B. 1 in 100
C. 1 in 1,000
D. 1 in 10,000
E. 1 in 100,000
B
If in a population in Hardy-Weinberg equilibrium the
frequency of the homozygous recessive genotype is
0.16, then the frequency of the dominant allele will be
A. 0.026.
B. 0.16.
C. 0.4.
D. 0.6.
E. 0.84.
D
___________ means that mating pairs are formed
without regard to genotype: two genotypes mate in
proportion to their relative frequencies population.
Random mating
A population having an allele frequency of 1.0 for
some allele is said to be __________ for that allele.
fixed
_____________ refers to the random, undirected
changes in allele frequency that occur by chance in all
populations, but particularly in small ones
Random Genetic Drift
Selection can result in a stable genetic polymorphism
if the ____________ genotype has the highest
fitnessRandom mating, fixed, Random Genetic Drift
and heterozygotes
heterozygotes
AND THEIR COMPLETE SOLUTIONS
Phenyketonuria is an inborn error of metabolism
caused by an autosomal recessive gene. The
frequency of this allele in the population is 0.03.
Assuming Hardy-Weinberg equilibrium, what is the
expected incidence of phenyketonuria among the
offspring of all matings in which both parents are
found to be carriers?
A. 0.0009
B. 0.03
C. 0.25
D. 0.5
C
The MN blood group phenotypes of 2,000 British
citizens were 596M, 978MN, and 426N. What is the
frequency of the NN genotype?
A. 0.106
B. 0.149
C. 0.457
D. 0.213
E. 0.915
D
What factor could cause the allelic frequencies of a
gene to shift randomly within a population?
,A. Genetic drift
B. High mutation rate
C. Assortative mating
D. Migration
E. Natural selection
A
Selection for or against a recessive allele in diploids is
inefficient when
A. the recessive allele is rare.
B. the recessive allele is frequent.
C. the frequencies of the recessive allele in males and
females are different.
D. the population is not in Hardy-Weinberg
equilibrium.
A
Which of the following processes does not contribute
to changing allele frequencies in populations?
A. mutation
B. inbreeding
C. migration
D. natural selection
E. genetic drift
B
A trait due to a recessive X-linked allele in a large,
randomly mating population affects one male in ten.
What is the frequency of affected females?
A. 1 in 10
, B. 1 in 100
C. 1 in 1,000
D. 1 in 10,000
E. 1 in 100,000
B
If in a population in Hardy-Weinberg equilibrium the
frequency of the homozygous recessive genotype is
0.16, then the frequency of the dominant allele will be
A. 0.026.
B. 0.16.
C. 0.4.
D. 0.6.
E. 0.84.
D
___________ means that mating pairs are formed
without regard to genotype: two genotypes mate in
proportion to their relative frequencies population.
Random mating
A population having an allele frequency of 1.0 for
some allele is said to be __________ for that allele.
fixed
_____________ refers to the random, undirected
changes in allele frequency that occur by chance in all
populations, but particularly in small ones
Random Genetic Drift
Selection can result in a stable genetic polymorphism
if the ____________ genotype has the highest
fitnessRandom mating, fixed, Random Genetic Drift
and heterozygotes
heterozygotes
