NURS 611: Advanced Pathophysiology - Genetic & Congenital
Disorders 2026 |Maryville
1. A point mutation in the DNA sequence that results in a premature stop codon
is referred to as which of the following?
A. Missense mutation
B. Nonsense mutation
C. Silent mutation
D. Frameshift mutation
Answer: B
Rationale: A nonsense mutation occurs when a single base pair substitution changes a
codon that previously coded for an amino acid into a stop codon, resulting in a truncated,
usually nonfunctional protein.
2. Which process involves the enzyme DNA polymerase adding the correct
nucleotides to the free end of a growing DNA strand?
A. Transcription
B. Translation
C. Replication
D. Splicing
Answer: C
Rationale: DNA replication is the process of copying a DNA molecule; DNA polymerase is
the primary enzyme responsible for synthesizing the new strand by adding nucleotides.
,3. A person born with a 45,X karyotype is diagnosed with which condition?
A. Klinefelter syndrome
B. Down syndrome
C. Turner syndrome
D. Cri du Chat syndrome
Answer: C
Rationale: Turner syndrome is characterized by the presence of a single X chromosome
(monosomy X), resulting in a 45,X karyotype, typically presenting with short stature and
ovarian dysgenesis.
4. What is the primary cause of trisomy 21 (Down syndrome)?
A. Environmental teratogens during the first trimester
B. Paternal translocation
C. Maternal nondisjunction during meiosis
D. Somatic mutation after fertilization
Answer: C
Rationale: In approximately 95% of Down syndrome cases, the cause is nondisjunction
during the formation of the mother’s egg cell, leading to an extra copy of chromosome 21.
5. An individual possesses two different alleles at a given locus. This individual is
described as:
A. Heterozygous
B. Hemizygous
C. Homozygous
D. Aneuploid
Answer: A
Rationale: Heterozygous refers to having two different alleles for a specific gene, whereas
homozygous refers to having two identical alleles.
, 6. In autosomal dominant disorders, what is the probability that an affected
heterozygous parent will pass the trait to their offspring?
A. 25%
B. 75%
C. 50%
D. 100%
Answer: C
Rationale: If one parent is heterozygous (Aa) and the other is unaffected (aa), there is a
50% chance for each child to inherit the dominant ‘A’ allele and be affected.
7. Which condition is a well-known example of an autosomal recessive disorder
caused by a defect in chloride ion transport?
A. Cystic fibrosis
B. Neurofibromatosis
C. Huntington disease
D. Sickle cell anemia
Answer: A
Rationale: Cystic fibrosis is caused by mutations in the CFTR gene, which codes for a
protein that regulates the movement of chloride ions across cell membranes.
8. A male child is diagnosed with Hemophilia A. From which parent did he most
likely inherit the defective gene?
A. The father
B. Neither, it is always a de novo mutation
C. Both parents
D. The mother
Answer: D
Disorders 2026 |Maryville
1. A point mutation in the DNA sequence that results in a premature stop codon
is referred to as which of the following?
A. Missense mutation
B. Nonsense mutation
C. Silent mutation
D. Frameshift mutation
Answer: B
Rationale: A nonsense mutation occurs when a single base pair substitution changes a
codon that previously coded for an amino acid into a stop codon, resulting in a truncated,
usually nonfunctional protein.
2. Which process involves the enzyme DNA polymerase adding the correct
nucleotides to the free end of a growing DNA strand?
A. Transcription
B. Translation
C. Replication
D. Splicing
Answer: C
Rationale: DNA replication is the process of copying a DNA molecule; DNA polymerase is
the primary enzyme responsible for synthesizing the new strand by adding nucleotides.
,3. A person born with a 45,X karyotype is diagnosed with which condition?
A. Klinefelter syndrome
B. Down syndrome
C. Turner syndrome
D. Cri du Chat syndrome
Answer: C
Rationale: Turner syndrome is characterized by the presence of a single X chromosome
(monosomy X), resulting in a 45,X karyotype, typically presenting with short stature and
ovarian dysgenesis.
4. What is the primary cause of trisomy 21 (Down syndrome)?
A. Environmental teratogens during the first trimester
B. Paternal translocation
C. Maternal nondisjunction during meiosis
D. Somatic mutation after fertilization
Answer: C
Rationale: In approximately 95% of Down syndrome cases, the cause is nondisjunction
during the formation of the mother’s egg cell, leading to an extra copy of chromosome 21.
5. An individual possesses two different alleles at a given locus. This individual is
described as:
A. Heterozygous
B. Hemizygous
C. Homozygous
D. Aneuploid
Answer: A
Rationale: Heterozygous refers to having two different alleles for a specific gene, whereas
homozygous refers to having two identical alleles.
, 6. In autosomal dominant disorders, what is the probability that an affected
heterozygous parent will pass the trait to their offspring?
A. 25%
B. 75%
C. 50%
D. 100%
Answer: C
Rationale: If one parent is heterozygous (Aa) and the other is unaffected (aa), there is a
50% chance for each child to inherit the dominant ‘A’ allele and be affected.
7. Which condition is a well-known example of an autosomal recessive disorder
caused by a defect in chloride ion transport?
A. Cystic fibrosis
B. Neurofibromatosis
C. Huntington disease
D. Sickle cell anemia
Answer: A
Rationale: Cystic fibrosis is caused by mutations in the CFTR gene, which codes for a
protein that regulates the movement of chloride ions across cell membranes.
8. A male child is diagnosed with Hemophilia A. From which parent did he most
likely inherit the defective gene?
A. The father
B. Neither, it is always a de novo mutation
C. Both parents
D. The mother
Answer: D
