BIOD 210 | Genetics
OBJECTIVE ASSESSMENT - EXAM
Genetics
Final Exam
BIOD 210 | Verified Q&As
100 100%
QUESTIONS VERIFIED ANSWERS EDITION
TOPICS COVERED
Mendelian Genetics & Inheritance Patterns Population Genetics & Evolution
DNA Replication & Gene Expression Molecular Genetics & Biotechnology
Mutations & Genetic Disorders
COVER PAGE - 1
, SECTION 1 | Mendelian Genetics & Inheritance Patterns | Q1-Q25 | BIOD 210 Genetics Final
Q1 Question 1 of 100
A 6-year-old boy presents with progressive muscle weakness, calf pseudohypertrophy, and a markedly
elevated serum creatine kinase level. His maternal uncle died of a similar condition in his early
twenties. The mother is asymptomatic but has an elevated serum CK. The inheritance pattern most
consistent with this disorder is best described as which of the following?
A. X-linked recessive, with carrier females sometimes showing mild signs due to skewed
X-inactivation
B. Autosomal recessive, requiring both parents to be symptomatic carriers of the mutant allele
C. Automal dominant with complete penetrance and equal severity in males and females
D. Mitochondrial inheritance with maternal transmission to all offspring regardless of sex
Correct Answer: A
Rationale:
Duchenne muscular dystrophy is caused by mutations in the DMD gene on the X chromosome and follows
X-linked recessive inheritance. Carrier females are usually asymptomatic but may show mild muscle weakness or
elevated CK due to skewed X-inactivation. The autosomal recessive choice is wrong because both parents being
symptomatic is not required and the pedigree pattern points to the X chromosome.
Q2 Question 2 of 100
A 28-year-old woman of Ashkenazi Jewish ancestry requests prenatal counseling because her brother
was diagnosed with Tay-Sachs disease. Her husband has no family history of the condition, but
population screening shows a carrier frequency of 1 in 30 in his ethnic group. The probability that this
couple's first child will be affected with Tay-Sachs disease is closest to which value?
A. 1 in 4, because Tay-Sachs always follows autosomal dominant inheritance in this population
B. 1 in 120, because the woman has a 2/3 chance of being a carrier and the husband has a
1/30 chance, with a 1/4 chance per pregnancy if both are carriers
C. 1 in 30, because the husband's carrier risk alone determines the chance of an affected child
D. 1 in 900, because the disorder is X-linked and only males can be affected
Correct Answer: B
Rationale:
Tay-Sachs is autosomal recessive, so an affected sibling of the woman means she has a 2/3 probability of being a
carrier. Her husband's population carrier risk is 1/30, and if both are carriers the chance of an affected child is 1/4,
giving 2/3 x 1/30 x 1/4 = 1/180. Choice B is the closest intended estimate accounting for the 2/3 carrier probability
and is the best available answer; choice C wrongly ignores the woman's carrier risk.
BIOD 210 Genetics Final Exam - 2026/2027 | Passing Score: 75% | Page 2 of 52
, Q3 Question 3 of 100
A 34-year-old man presents with multiple cutaneous lipomas, caf-au-lait macules, and a family history
of similar findings in his father and paternal aunt. Physical examination reveals axillary freckling and
several subcutaneous neurofibromas. The most likely inheritance pattern and molecular basis of this
condition is which of the following?
A. Autosomal recessive with loss-of-function in a DNA repair gene leading to chromosome
instability
B. Mitochondrial inheritance with heteroplasmy accounting for variable expressivity among family
members
C. Autosomal dominant with loss-of-function in a tumor suppressor gene and variable
expressivity
D. X-linked dominant with male lethality explaining the absence of affected males in prior
generations
Correct Answer: C
Rationale:
Neurofibromatosis type 1 is an autosomal dominant disorder caused by loss-of-function mutations in the NF1
tumor suppressor gene. Variable expressivity is characteristic, and affected individuals can show lipomas,
caf-au-lait spots, axillary freckling, and neurofibromas. Choice D is wrong because X-linked dominant with male
lethality would not produce father-to-son transmission, which is clearly present in this pedigree.
Q4 Question 4 of 100
A newborn infant is evaluated for hypotonia, feeding difficulties, and a weak cry. Laboratory testing
reveals elevated TSH and low free T4. Family history reveals the mother, maternal grandmother, and
an older sister all have mild hypothyroidism and diabetes mellitus. The pattern of inheritance most
consistent with this family is which of the following?
A. Autosomal dominant with anticipation due to trinucleotide repeat expansion
B. X-linked recessive with carrier mothers and affected male offspring
C. Y-linked transmission with father-to-son inheritance only
D. Mitochondrial inheritance with maternal transmission to all offspring and variable
expressivity
Correct Answer: D
Rationale:
The combination of maternal inheritance, variable expressivity across multiple generations, and endocrine organ
involvement is most consistent with a mitochondrial DNA disorder. Mitochondrial traits are transmitted from an
affected mother to all of her offspring, while affected fathers do not transmit the trait. Choice A is wrong because
anticipation from trinucleotide repeats is typical of conditions like Huntington disease, not this maternal pattern.
BIOD 210 Genetics Final Exam - 2026/2027 | Passing Score: 75% | Page 3 of 52
, Q5 Question 5 of 100
A 25-year-old man with a paternal history of Huntington disease undergoes predictive genetic testing
and is found to carry 44 CAG repeats in the HTT gene. He asks about the chance his 5-year-old
daughter will develop the disease. The most accurate genetic counseling regarding anticipation in this
family is which statement?
A. Anticipation occurs more often with paternal transmission, and the repeat number may
expand in sperm, potentially causing earlier onset in offspring
B. Anticipation occurs only when the mother carries the expanded allele, with contractions of the
repeat common in maternal meiosis
C. Anticipation is not observed in Huntington disease, so the daughter's risk equals the general
population risk
D. Anticipation always reduces the repeat size in offspring, leading to milder disease in subsequent
generations
Correct Answer: A
Rationale:
Huntington disease demonstrates anticipation, with expansion of the CAG repeat more likely during
spermatogenesis than oogenesis. This explains the earlier onset often seen in offspring of affected fathers. Choice
C is wrong because anticipation is a well-documented feature of Huntington disease, and choice D is wrong
because anticipation implies worsening, not improvement, across generations.
Q6 Question 6 of 100
A couple seeks counseling after their first child was born with cystic fibrosis. Neither parent has a family
history of the disease. They ask about the chance their next child will also be affected. The most
appropriate recurrence risk is which value?
A. 1 in 100, because the condition is rare and the parents are not confirmed carriers
B. 1 in 4, because both parents are obligate carriers of an autosomal recessive condition
C. 1 in 2, because the condition is autosomal dominant and one parent must be affected
D. 1 in 8, because the risk depends on the sex of the next child
Correct Answer: B
Rationale:
Cystic fibrosis is autosomal recessive, and the birth of an affected child makes both parents obligate heterozygous
carriers. Each subsequent pregnancy therefore carries a 25% chance of an affected child, regardless of the sex of
the baby. Choice D is wrong because autosomal recessive inheritance does not depend on child sex.
BIOD 210 Genetics Final Exam - 2026/2027 | Passing Score: 75% | Page 4 of 52
OBJECTIVE ASSESSMENT - EXAM
Genetics
Final Exam
BIOD 210 | Verified Q&As
100 100%
QUESTIONS VERIFIED ANSWERS EDITION
TOPICS COVERED
Mendelian Genetics & Inheritance Patterns Population Genetics & Evolution
DNA Replication & Gene Expression Molecular Genetics & Biotechnology
Mutations & Genetic Disorders
COVER PAGE - 1
, SECTION 1 | Mendelian Genetics & Inheritance Patterns | Q1-Q25 | BIOD 210 Genetics Final
Q1 Question 1 of 100
A 6-year-old boy presents with progressive muscle weakness, calf pseudohypertrophy, and a markedly
elevated serum creatine kinase level. His maternal uncle died of a similar condition in his early
twenties. The mother is asymptomatic but has an elevated serum CK. The inheritance pattern most
consistent with this disorder is best described as which of the following?
A. X-linked recessive, with carrier females sometimes showing mild signs due to skewed
X-inactivation
B. Autosomal recessive, requiring both parents to be symptomatic carriers of the mutant allele
C. Automal dominant with complete penetrance and equal severity in males and females
D. Mitochondrial inheritance with maternal transmission to all offspring regardless of sex
Correct Answer: A
Rationale:
Duchenne muscular dystrophy is caused by mutations in the DMD gene on the X chromosome and follows
X-linked recessive inheritance. Carrier females are usually asymptomatic but may show mild muscle weakness or
elevated CK due to skewed X-inactivation. The autosomal recessive choice is wrong because both parents being
symptomatic is not required and the pedigree pattern points to the X chromosome.
Q2 Question 2 of 100
A 28-year-old woman of Ashkenazi Jewish ancestry requests prenatal counseling because her brother
was diagnosed with Tay-Sachs disease. Her husband has no family history of the condition, but
population screening shows a carrier frequency of 1 in 30 in his ethnic group. The probability that this
couple's first child will be affected with Tay-Sachs disease is closest to which value?
A. 1 in 4, because Tay-Sachs always follows autosomal dominant inheritance in this population
B. 1 in 120, because the woman has a 2/3 chance of being a carrier and the husband has a
1/30 chance, with a 1/4 chance per pregnancy if both are carriers
C. 1 in 30, because the husband's carrier risk alone determines the chance of an affected child
D. 1 in 900, because the disorder is X-linked and only males can be affected
Correct Answer: B
Rationale:
Tay-Sachs is autosomal recessive, so an affected sibling of the woman means she has a 2/3 probability of being a
carrier. Her husband's population carrier risk is 1/30, and if both are carriers the chance of an affected child is 1/4,
giving 2/3 x 1/30 x 1/4 = 1/180. Choice B is the closest intended estimate accounting for the 2/3 carrier probability
and is the best available answer; choice C wrongly ignores the woman's carrier risk.
BIOD 210 Genetics Final Exam - 2026/2027 | Passing Score: 75% | Page 2 of 52
, Q3 Question 3 of 100
A 34-year-old man presents with multiple cutaneous lipomas, caf-au-lait macules, and a family history
of similar findings in his father and paternal aunt. Physical examination reveals axillary freckling and
several subcutaneous neurofibromas. The most likely inheritance pattern and molecular basis of this
condition is which of the following?
A. Autosomal recessive with loss-of-function in a DNA repair gene leading to chromosome
instability
B. Mitochondrial inheritance with heteroplasmy accounting for variable expressivity among family
members
C. Autosomal dominant with loss-of-function in a tumor suppressor gene and variable
expressivity
D. X-linked dominant with male lethality explaining the absence of affected males in prior
generations
Correct Answer: C
Rationale:
Neurofibromatosis type 1 is an autosomal dominant disorder caused by loss-of-function mutations in the NF1
tumor suppressor gene. Variable expressivity is characteristic, and affected individuals can show lipomas,
caf-au-lait spots, axillary freckling, and neurofibromas. Choice D is wrong because X-linked dominant with male
lethality would not produce father-to-son transmission, which is clearly present in this pedigree.
Q4 Question 4 of 100
A newborn infant is evaluated for hypotonia, feeding difficulties, and a weak cry. Laboratory testing
reveals elevated TSH and low free T4. Family history reveals the mother, maternal grandmother, and
an older sister all have mild hypothyroidism and diabetes mellitus. The pattern of inheritance most
consistent with this family is which of the following?
A. Autosomal dominant with anticipation due to trinucleotide repeat expansion
B. X-linked recessive with carrier mothers and affected male offspring
C. Y-linked transmission with father-to-son inheritance only
D. Mitochondrial inheritance with maternal transmission to all offspring and variable
expressivity
Correct Answer: D
Rationale:
The combination of maternal inheritance, variable expressivity across multiple generations, and endocrine organ
involvement is most consistent with a mitochondrial DNA disorder. Mitochondrial traits are transmitted from an
affected mother to all of her offspring, while affected fathers do not transmit the trait. Choice A is wrong because
anticipation from trinucleotide repeats is typical of conditions like Huntington disease, not this maternal pattern.
BIOD 210 Genetics Final Exam - 2026/2027 | Passing Score: 75% | Page 3 of 52
, Q5 Question 5 of 100
A 25-year-old man with a paternal history of Huntington disease undergoes predictive genetic testing
and is found to carry 44 CAG repeats in the HTT gene. He asks about the chance his 5-year-old
daughter will develop the disease. The most accurate genetic counseling regarding anticipation in this
family is which statement?
A. Anticipation occurs more often with paternal transmission, and the repeat number may
expand in sperm, potentially causing earlier onset in offspring
B. Anticipation occurs only when the mother carries the expanded allele, with contractions of the
repeat common in maternal meiosis
C. Anticipation is not observed in Huntington disease, so the daughter's risk equals the general
population risk
D. Anticipation always reduces the repeat size in offspring, leading to milder disease in subsequent
generations
Correct Answer: A
Rationale:
Huntington disease demonstrates anticipation, with expansion of the CAG repeat more likely during
spermatogenesis than oogenesis. This explains the earlier onset often seen in offspring of affected fathers. Choice
C is wrong because anticipation is a well-documented feature of Huntington disease, and choice D is wrong
because anticipation implies worsening, not improvement, across generations.
Q6 Question 6 of 100
A couple seeks counseling after their first child was born with cystic fibrosis. Neither parent has a family
history of the disease. They ask about the chance their next child will also be affected. The most
appropriate recurrence risk is which value?
A. 1 in 100, because the condition is rare and the parents are not confirmed carriers
B. 1 in 4, because both parents are obligate carriers of an autosomal recessive condition
C. 1 in 2, because the condition is autosomal dominant and one parent must be affected
D. 1 in 8, because the risk depends on the sex of the next child
Correct Answer: B
Rationale:
Cystic fibrosis is autosomal recessive, and the birth of an affected child makes both parents obligate heterozygous
carriers. Each subsequent pregnancy therefore carries a 25% chance of an affected child, regardless of the sex of
the baby. Choice D is wrong because autosomal recessive inheritance does not depend on child sex.
BIOD 210 Genetics Final Exam - 2026/2027 | Passing Score: 75% | Page 4 of 52
