BIOL101 Population Genetics
Comprehensive Practice Exam
Essential Biology I w/Lab | 100 Questions
with Detailed Explanations
SECTION A: HARDY-WEINBERG EQUILIBRIUM
FUNDAMENTALS (Questions 1–20)
Question 1
The Hardy-Weinberg principle states that allele frequencies in a
population will remain constant if certain conditions are met.
Which of the following is NOT one of these conditions?
A) No mutations
B) Random mating
C) Natural selection
D) Large population size
E) No gene flow
Correct Answer: C) Natural selection
Explanation: The Hardy-Weinberg conditions are: (1) no
mutations, (2) random mating, (3) no natural selection, (4)
,extremely large population size (no genetic drift), and (5) no
gene flow. Natural selection causes evolution; it is NOT a
condition for Hardy-Weinberg equilibrium. If any condition is
violated, allele frequencies will change.
Question 2
In the Hardy-Weinberg equation p² + 2pq + q² = 1, what
does p represent?
A) Frequency of the recessive allele
B) Frequency of the dominant allele
C) Frequency of homozygous dominant individuals
D) Frequency of heterozygous individuals
E) Frequency of the entire population
Correct Answer: B) Frequency of the dominant allele
Explanation: In the Hardy-Weinberg equation, p represents the
frequency of the dominant allele, and q represents the
frequency of the recessive allele. Since there are only two alleles
for a given gene in a diploid population, p + q = 1. The terms
p², 2pq, and q² represent genotype frequencies.
Question 3
In the Hardy-Weinberg equation, what does q² represent?
A) Frequency of the dominant allele
B) Frequency of the recessive allele
C) Frequency of homozygous recessive individuals
,D) Frequency of heterozygous individuals
E) Frequency of homozygous dominant individuals
Correct Answer: C) Frequency of homozygous recessive
individuals
Explanation: q² represents the frequency of individuals who
are homozygous recessive (genotype aa). If the frequency of
the recessive allele (q) is known, q² can be calculated to
determine the proportion of the population that expresses the
recessive phenotype (assuming complete dominance).
Question 4
What does 2pq represent in the Hardy-Weinberg equation?
A) Frequency of homozygous dominant individuals
B) Frequency of homozygous recessive individuals
C) Frequency of heterozygous individuals
D) Frequency of both alleles combined
E) Frequency of the entire population
Correct Answer: C) Frequency of heterozygous individuals
Explanation: 2pq represents the frequency of heterozygous
individuals (genotype Aa). The factor 2 accounts for the two
possible ways a heterozygote can be formed (allele A from the
mother and allele a from the father, or vice versa). The sum of
all genotype frequencies (p² + 2pq + q²) equals 1, representing
the entire population.
, Question 5
If the frequency of the dominant allele (p) is 0.7, what is the
frequency of the recessive allele (q)?
A) 0.3
B) 0.7
C) 1.0
D) 0.49
E) 0.21
Correct Answer: A) 0.3
Explanation: Since p + q = 1, then q = 1 - p. If p = 0.7, then q
= 1 - 0.7 = 0.3. The frequency of the recessive allele is 0.3, or
30% of the allele pool.
Question 6
In a population of 500 individuals, 180 are homozygous
dominant (AA), 240 are heterozygous (Aa), and 80 are
homozygous recessive (aa). What is the frequency of the
dominant allele (p)?
A) 0.30
B) 0.36
C) 0.50
D) 0.60
E) 0.64
Correct Answer: D) 0.60
Explanation: To calculate allele frequencies:
Comprehensive Practice Exam
Essential Biology I w/Lab | 100 Questions
with Detailed Explanations
SECTION A: HARDY-WEINBERG EQUILIBRIUM
FUNDAMENTALS (Questions 1–20)
Question 1
The Hardy-Weinberg principle states that allele frequencies in a
population will remain constant if certain conditions are met.
Which of the following is NOT one of these conditions?
A) No mutations
B) Random mating
C) Natural selection
D) Large population size
E) No gene flow
Correct Answer: C) Natural selection
Explanation: The Hardy-Weinberg conditions are: (1) no
mutations, (2) random mating, (3) no natural selection, (4)
,extremely large population size (no genetic drift), and (5) no
gene flow. Natural selection causes evolution; it is NOT a
condition for Hardy-Weinberg equilibrium. If any condition is
violated, allele frequencies will change.
Question 2
In the Hardy-Weinberg equation p² + 2pq + q² = 1, what
does p represent?
A) Frequency of the recessive allele
B) Frequency of the dominant allele
C) Frequency of homozygous dominant individuals
D) Frequency of heterozygous individuals
E) Frequency of the entire population
Correct Answer: B) Frequency of the dominant allele
Explanation: In the Hardy-Weinberg equation, p represents the
frequency of the dominant allele, and q represents the
frequency of the recessive allele. Since there are only two alleles
for a given gene in a diploid population, p + q = 1. The terms
p², 2pq, and q² represent genotype frequencies.
Question 3
In the Hardy-Weinberg equation, what does q² represent?
A) Frequency of the dominant allele
B) Frequency of the recessive allele
C) Frequency of homozygous recessive individuals
,D) Frequency of heterozygous individuals
E) Frequency of homozygous dominant individuals
Correct Answer: C) Frequency of homozygous recessive
individuals
Explanation: q² represents the frequency of individuals who
are homozygous recessive (genotype aa). If the frequency of
the recessive allele (q) is known, q² can be calculated to
determine the proportion of the population that expresses the
recessive phenotype (assuming complete dominance).
Question 4
What does 2pq represent in the Hardy-Weinberg equation?
A) Frequency of homozygous dominant individuals
B) Frequency of homozygous recessive individuals
C) Frequency of heterozygous individuals
D) Frequency of both alleles combined
E) Frequency of the entire population
Correct Answer: C) Frequency of heterozygous individuals
Explanation: 2pq represents the frequency of heterozygous
individuals (genotype Aa). The factor 2 accounts for the two
possible ways a heterozygote can be formed (allele A from the
mother and allele a from the father, or vice versa). The sum of
all genotype frequencies (p² + 2pq + q²) equals 1, representing
the entire population.
, Question 5
If the frequency of the dominant allele (p) is 0.7, what is the
frequency of the recessive allele (q)?
A) 0.3
B) 0.7
C) 1.0
D) 0.49
E) 0.21
Correct Answer: A) 0.3
Explanation: Since p + q = 1, then q = 1 - p. If p = 0.7, then q
= 1 - 0.7 = 0.3. The frequency of the recessive allele is 0.3, or
30% of the allele pool.
Question 6
In a population of 500 individuals, 180 are homozygous
dominant (AA), 240 are heterozygous (Aa), and 80 are
homozygous recessive (aa). What is the frequency of the
dominant allele (p)?
A) 0.30
B) 0.36
C) 0.50
D) 0.60
E) 0.64
Correct Answer: D) 0.60
Explanation: To calculate allele frequencies:
