BIOD 102/BIOD102 Essential Biology II with Lab Review
Actual 2026/2027 with Detailed Rationales | 100%
Verified | Pass Guaranteed
SECTION 1: EVOLUTION & POPULATION GENETICS (Questions 1–16)
Q1: Which of the following is a requirement for a population to be in Hardy-Weinberg
equilibrium?
A. Small population size
B. Non-random mating
C. No gene flow
D. Natural selection must be occurring
Correct Answer: C
Rationale: Correct because the Hardy-Weinberg equilibrium requires no mutation, no
gene flow, random mating, no natural selection, and a large population size. Gene flow
introduces new alleles and disrupts allele frequencies.
Q2: In a population of 10,000 individuals, the frequency of the recessive allele (q) for a
particular trait is 0.3. What is the frequency of heterozygous individuals?
A. 0.09
B. 0.21
C. 0.42
D. 0.49
Correct Answer: C
Rationale: Correct because using the Hardy-Weinberg equation, p = 1 - q = 0.7, and the
heterozygote frequency is 2pq = 2(0.7)(0.3) = 0.42.
Q3: A population of beetles exhibits color variation. Over several generations, the
frequency of dark-colored beetles increases because they are less visible to predators.
This is an example of:
A. Genetic drift
B. Directional selection
C. Disruptive selection
D. Stabilizing selection
,Correct Answer: B
Rationale: Correct because directional selection favors one extreme phenotype over
another, causing allele frequencies to shift in one direction; here, dark coloration is
favored.
Q4: The bottleneck effect is best described as:
A. A decrease in genetic variation due to a drastic reduction in population size
B. An increase in allele frequency due to immigration
C. A random change in allele frequency in a large population
D. The movement of alleles between populations via mating
Correct Answer: A
Rationale: Correct because the bottleneck effect occurs when a population is drastically
reduced in size, causing a loss of genetic variation and a change in allele frequencies by
chance.
Q5: Which evolutionary mechanism consistently results in a loss of genetic variation
from a population?
A. Mutation
B. Gene flow
C. Genetic drift
D. Non-random mating
Correct Answer: C
Rationale: Correct because genetic drift involves random changes in allele frequencies,
particularly in small populations, and consistently leads to a loss of genetic variation
over time.
Q6: In a population at Hardy-Weinberg equilibrium, 16% of individuals express a
recessive phenotype. What is the frequency of the dominant allele?
A. 0.16
B. 0.40
C. 0.60
D. 0.84
Correct Answer: C
Rationale: Correct because q² = 0.16, so q = 0.40; therefore p = 1 - q = 0.60, which is the
frequency of the dominant allele.
,Q7: Two populations of the same species are separated by a mountain range and evolve
into distinct species over time. This process is called:
A. Sympatric speciation
B. Allopatric speciation
C. Parapatric speciation
D. Adaptive radiation
Correct Answer: B
Rationale: Correct because allopatric speciation occurs when populations are
geographically isolated from one another, preventing gene flow and allowing
independent evolutionary divergence.
Q8: Which of the following is an example of sympatric speciation?
A. Two squirrel populations separated by a river
B. A new plant species arising from polyploidy in a single generation
C. Finches on different Galápagos islands evolving different beak shapes
D. Wolves and coyotes diverging in adjacent territories
Correct Answer: B
Rationale: Correct because sympatric speciation occurs without geographic isolation;
polyploidy in plants can create a reproductively isolated new species within the same
geographic area in a single generation.
Q9: A population of mice lives in an area where light-colored soil is gradually replaced by
dark volcanic rock. Over time, dark-colored mice become more common. This pattern
represents:
A. Stabilizing selection
B. Disruptive selection
C. Directional selection
D. Balancing selection
Correct Answer: C
Rationale: Correct because directional selection shifts the population phenotype toward
one extreme; as the environment favors dark coloration, the population mean shifts
toward darker phenotypes.
Q10: The founder effect differs from the bottleneck effect in that the founder effect:
A. Occurs in large populations
B. Involves a small group establishing a new population
, C. Always increases genetic diversity
D. Results from natural selection
Correct Answer: B
Rationale: Correct because the founder effect occurs when a small group of individuals
establishes a new population, carrying only a fraction of the original population's genetic
variation.
Q11: In a population, the frequency of allele A is 0.6 and allele a is 0.4. If the population
is in Hardy-Weinberg equilibrium, what percentage of individuals are homozygous
dominant?
A. 16%
B. 24%
C. 36%
D. 48%
Correct Answer: C
Rationale: Correct because the frequency of the homozygous dominant genotype (AA)
is p² = (0.6)² = 0.36, or 36% of the population.
Q12: Non-random mating, such as inbreeding, affects genotype frequencies by:
A. Increasing heterozygosity
B. Decreasing heterozygosity
C. Having no effect on genotype frequencies
D. Increasing the mutation rate
Correct Answer: B
Rationale: Correct because inbreeding increases homozygosity and decreases
heterozygosity without changing allele frequencies in the population.
Q13: Which of the following conditions would NOT disrupt Hardy-Weinberg equilibrium?
A. A population of 50 individuals
B. Individuals mating at random
C. Immigration of individuals from a neighboring population
D. Differential survival of phenotypes
Correct Answer: B
Rationale: Correct because random mating is a required condition for Hardy-Weinberg
equilibrium; all other options violate one or more of the equilibrium conditions.
Actual 2026/2027 with Detailed Rationales | 100%
Verified | Pass Guaranteed
SECTION 1: EVOLUTION & POPULATION GENETICS (Questions 1–16)
Q1: Which of the following is a requirement for a population to be in Hardy-Weinberg
equilibrium?
A. Small population size
B. Non-random mating
C. No gene flow
D. Natural selection must be occurring
Correct Answer: C
Rationale: Correct because the Hardy-Weinberg equilibrium requires no mutation, no
gene flow, random mating, no natural selection, and a large population size. Gene flow
introduces new alleles and disrupts allele frequencies.
Q2: In a population of 10,000 individuals, the frequency of the recessive allele (q) for a
particular trait is 0.3. What is the frequency of heterozygous individuals?
A. 0.09
B. 0.21
C. 0.42
D. 0.49
Correct Answer: C
Rationale: Correct because using the Hardy-Weinberg equation, p = 1 - q = 0.7, and the
heterozygote frequency is 2pq = 2(0.7)(0.3) = 0.42.
Q3: A population of beetles exhibits color variation. Over several generations, the
frequency of dark-colored beetles increases because they are less visible to predators.
This is an example of:
A. Genetic drift
B. Directional selection
C. Disruptive selection
D. Stabilizing selection
,Correct Answer: B
Rationale: Correct because directional selection favors one extreme phenotype over
another, causing allele frequencies to shift in one direction; here, dark coloration is
favored.
Q4: The bottleneck effect is best described as:
A. A decrease in genetic variation due to a drastic reduction in population size
B. An increase in allele frequency due to immigration
C. A random change in allele frequency in a large population
D. The movement of alleles between populations via mating
Correct Answer: A
Rationale: Correct because the bottleneck effect occurs when a population is drastically
reduced in size, causing a loss of genetic variation and a change in allele frequencies by
chance.
Q5: Which evolutionary mechanism consistently results in a loss of genetic variation
from a population?
A. Mutation
B. Gene flow
C. Genetic drift
D. Non-random mating
Correct Answer: C
Rationale: Correct because genetic drift involves random changes in allele frequencies,
particularly in small populations, and consistently leads to a loss of genetic variation
over time.
Q6: In a population at Hardy-Weinberg equilibrium, 16% of individuals express a
recessive phenotype. What is the frequency of the dominant allele?
A. 0.16
B. 0.40
C. 0.60
D. 0.84
Correct Answer: C
Rationale: Correct because q² = 0.16, so q = 0.40; therefore p = 1 - q = 0.60, which is the
frequency of the dominant allele.
,Q7: Two populations of the same species are separated by a mountain range and evolve
into distinct species over time. This process is called:
A. Sympatric speciation
B. Allopatric speciation
C. Parapatric speciation
D. Adaptive radiation
Correct Answer: B
Rationale: Correct because allopatric speciation occurs when populations are
geographically isolated from one another, preventing gene flow and allowing
independent evolutionary divergence.
Q8: Which of the following is an example of sympatric speciation?
A. Two squirrel populations separated by a river
B. A new plant species arising from polyploidy in a single generation
C. Finches on different Galápagos islands evolving different beak shapes
D. Wolves and coyotes diverging in adjacent territories
Correct Answer: B
Rationale: Correct because sympatric speciation occurs without geographic isolation;
polyploidy in plants can create a reproductively isolated new species within the same
geographic area in a single generation.
Q9: A population of mice lives in an area where light-colored soil is gradually replaced by
dark volcanic rock. Over time, dark-colored mice become more common. This pattern
represents:
A. Stabilizing selection
B. Disruptive selection
C. Directional selection
D. Balancing selection
Correct Answer: C
Rationale: Correct because directional selection shifts the population phenotype toward
one extreme; as the environment favors dark coloration, the population mean shifts
toward darker phenotypes.
Q10: The founder effect differs from the bottleneck effect in that the founder effect:
A. Occurs in large populations
B. Involves a small group establishing a new population
, C. Always increases genetic diversity
D. Results from natural selection
Correct Answer: B
Rationale: Correct because the founder effect occurs when a small group of individuals
establishes a new population, carrying only a fraction of the original population's genetic
variation.
Q11: In a population, the frequency of allele A is 0.6 and allele a is 0.4. If the population
is in Hardy-Weinberg equilibrium, what percentage of individuals are homozygous
dominant?
A. 16%
B. 24%
C. 36%
D. 48%
Correct Answer: C
Rationale: Correct because the frequency of the homozygous dominant genotype (AA)
is p² = (0.6)² = 0.36, or 36% of the population.
Q12: Non-random mating, such as inbreeding, affects genotype frequencies by:
A. Increasing heterozygosity
B. Decreasing heterozygosity
C. Having no effect on genotype frequencies
D. Increasing the mutation rate
Correct Answer: B
Rationale: Correct because inbreeding increases homozygosity and decreases
heterozygosity without changing allele frequencies in the population.
Q13: Which of the following conditions would NOT disrupt Hardy-Weinberg equilibrium?
A. A population of 50 individuals
B. Individuals mating at random
C. Immigration of individuals from a neighboring population
D. Differential survival of phenotypes
Correct Answer: B
Rationale: Correct because random mating is a required condition for Hardy-Weinberg
equilibrium; all other options violate one or more of the equilibrium conditions.
