AGRY 320 Final Exam questions with
correct answers 2025/2026
Suppose a three-point testcross was conducted involving the genes R, H, and Q. If the most
abundant classes are RQh and rqH and the rarest classes are RHq and rhQ, which gene is in the
middle? - correct answer ✔✔R
Consider a locus with two alleles, A and a. If the population is in Hardy-Weinberg equilibrium,
and if the frequency of the AA genotype is 0.25, what is the frequency of allele A? - correct
answer ✔✔0.5
A very large population of randomly-mating laboratory mice contains 35% white mice. White
coloring is caused by the homozygous recessive genotype, "aa". What is the allele frequency of
the recessive allele? - correct answer ✔✔0.59
Cystic fibrosis is a recessive condition that affects about 1 in 2,500 babies in the Caucasian
population of the United States. What is the frequency of the dominant allele in the
population? - correct answer ✔✔0.98
In bird populations, allele "A" encodes for brown color and is dominant over allele "a", which
encodes for white color. Population #1 consists of 1050 individuals with 300AA : 600 Aa : 250 aa
genotypes. Population #2 contains 770 individuals with 200 AA ; 400 Aa : 170 aa genotypes.
Three quarters of heterozygous brown birds from population #1 immigrate to population #2.
What is the allele frequency in population 2 BEFORE immigration takes place? - correct answer
✔✔A: 0.52
a: 0.48
A maize plant has the "Aa" genotype in its somatic cells. At Purdue's Agronomy Center for
Research and Education (ACRE), this plant is self-pollinated (or "selfed") 4 times. What
proportion of the resulting kernels have a heterozygous genotype? - correct answer ✔✔6.25%
, A maize plant has the "Aa" genotype in its somatic cells. At Purdue's Agronomy Center for
Research and Education, this plant is self-pollinated (or selfed) 4 times. What proportion of the
resulting kernels have a homozygous recessive genotype (aa)? - correct answer ✔✔46.87
An oligogenic trait in corn is controlled by 3 loci. For each locus there are only two alleles
segregating in the Purdue maize breeding population. These alleles are Q1/q1 for locus 1, Q2/q2
for locus 2, and Q3/q3 for locus 3. Assuming capital letters are favorable alleles and small letters
are unfavorable (or less favorable) alleles, and the gene action is additive for all loci, which
genotype shows the highest amount of this trait? - correct answer ✔✔Q1Q1Q2Q2Q3Q3
Favorable alleles Q1, Q2, and Q3 contribute 20, 10, and 5 bu/acre to corn yield, respectively,
while unfavorable alleles q1, q2, and q3 contribute none. The genotype with all unfavorable
alleles i.e., q1q1q2q2q3q3 would then perform minimally and express a baseline yield of 70
bu/acre. Assume that the gene action is additive and NOT dominant. What is the theoretical
yield of genotype q1q1q2q2Q3Q3? - correct answer ✔✔80
Favorable alleles Q1, Q2, and Q3 contribute 20, 10, and 5 bu/acre to corn yield, respectively,
while unfavorable alleles q1, q2, and q3 contribute none. The genotype with all unfavorable
alleles i.e., q1q1q2q2q3q3 would then perform minimally and express a baseline yield of 70
bu/acre. Assume that the gene action is additive and NOT dominant. What is the theoretical
yield of genotype q1q1Q2q2Q3Q3? - correct answer ✔✔90
Two traits in Purdue maize breeding program are considered: (1) drought tolerance (2)
carotenoid content. During field-based experiments, we estimate genetic and environmental
variance components for these two traits. For drought tolerance, the estimates were VG = 65
and VE = 35. For carotenoid content the estimates were VG = 92 and VE = 8. The broad-sense
heritability (H2) is __________ for drought tolerance and __________ for carotenoid content. -
correct answer ✔✔0.65, 0.92
In a two-point testcross of AaBb with homozygous recessive "aabb", we discover phenotypic
rations as follows. True or false: Ab and aB are the parental gametes.
correct answers 2025/2026
Suppose a three-point testcross was conducted involving the genes R, H, and Q. If the most
abundant classes are RQh and rqH and the rarest classes are RHq and rhQ, which gene is in the
middle? - correct answer ✔✔R
Consider a locus with two alleles, A and a. If the population is in Hardy-Weinberg equilibrium,
and if the frequency of the AA genotype is 0.25, what is the frequency of allele A? - correct
answer ✔✔0.5
A very large population of randomly-mating laboratory mice contains 35% white mice. White
coloring is caused by the homozygous recessive genotype, "aa". What is the allele frequency of
the recessive allele? - correct answer ✔✔0.59
Cystic fibrosis is a recessive condition that affects about 1 in 2,500 babies in the Caucasian
population of the United States. What is the frequency of the dominant allele in the
population? - correct answer ✔✔0.98
In bird populations, allele "A" encodes for brown color and is dominant over allele "a", which
encodes for white color. Population #1 consists of 1050 individuals with 300AA : 600 Aa : 250 aa
genotypes. Population #2 contains 770 individuals with 200 AA ; 400 Aa : 170 aa genotypes.
Three quarters of heterozygous brown birds from population #1 immigrate to population #2.
What is the allele frequency in population 2 BEFORE immigration takes place? - correct answer
✔✔A: 0.52
a: 0.48
A maize plant has the "Aa" genotype in its somatic cells. At Purdue's Agronomy Center for
Research and Education (ACRE), this plant is self-pollinated (or "selfed") 4 times. What
proportion of the resulting kernels have a heterozygous genotype? - correct answer ✔✔6.25%
, A maize plant has the "Aa" genotype in its somatic cells. At Purdue's Agronomy Center for
Research and Education, this plant is self-pollinated (or selfed) 4 times. What proportion of the
resulting kernels have a homozygous recessive genotype (aa)? - correct answer ✔✔46.87
An oligogenic trait in corn is controlled by 3 loci. For each locus there are only two alleles
segregating in the Purdue maize breeding population. These alleles are Q1/q1 for locus 1, Q2/q2
for locus 2, and Q3/q3 for locus 3. Assuming capital letters are favorable alleles and small letters
are unfavorable (or less favorable) alleles, and the gene action is additive for all loci, which
genotype shows the highest amount of this trait? - correct answer ✔✔Q1Q1Q2Q2Q3Q3
Favorable alleles Q1, Q2, and Q3 contribute 20, 10, and 5 bu/acre to corn yield, respectively,
while unfavorable alleles q1, q2, and q3 contribute none. The genotype with all unfavorable
alleles i.e., q1q1q2q2q3q3 would then perform minimally and express a baseline yield of 70
bu/acre. Assume that the gene action is additive and NOT dominant. What is the theoretical
yield of genotype q1q1q2q2Q3Q3? - correct answer ✔✔80
Favorable alleles Q1, Q2, and Q3 contribute 20, 10, and 5 bu/acre to corn yield, respectively,
while unfavorable alleles q1, q2, and q3 contribute none. The genotype with all unfavorable
alleles i.e., q1q1q2q2q3q3 would then perform minimally and express a baseline yield of 70
bu/acre. Assume that the gene action is additive and NOT dominant. What is the theoretical
yield of genotype q1q1Q2q2Q3Q3? - correct answer ✔✔90
Two traits in Purdue maize breeding program are considered: (1) drought tolerance (2)
carotenoid content. During field-based experiments, we estimate genetic and environmental
variance components for these two traits. For drought tolerance, the estimates were VG = 65
and VE = 35. For carotenoid content the estimates were VG = 92 and VE = 8. The broad-sense
heritability (H2) is __________ for drought tolerance and __________ for carotenoid content. -
correct answer ✔✔0.65, 0.92
In a two-point testcross of AaBb with homozygous recessive "aabb", we discover phenotypic
rations as follows. True or false: Ab and aB are the parental gametes.
