WGU D115 OA and Pre-OA Exam Actual Exam
2026/2027 Update | Comprehensive Exam Questions
with Verified Answers and Detailed Rationales (100%
Fully Solved) | Already Graded A+
SECTION 1: GENETICS & GENOMIC DISORDERS
Question 1
Which type of genetic disease affects males more frequently than females?
A) Autosomal dominant
B) Autosomal recessive
C) X-linked recessive
D) Mitochondrial
Answer: C
Rationale: X-linked recessive disorders affect males more frequently because males
have only one X chromosome. A single recessive mutation on that X chromosome
will be expressed. Females have two X chromosomes, so the presence of a normal
second X can mask the mutation.
Question 2
Chromosomal abnormalities are the leading known cause of which two
conditions?
A) Intellectual disability and fetal miscarriage
B) Respiratory disorders and cardiovascular disease
C) Mental illness and autoimmune disorders
D) Diabetes and hypertension
,Answer: A
Rationale: Chromosomal abnormalities are the leading known cause of intellectual
disability and fetal miscarriage.
Question 3
What are three examples of prenatal diagnostic studies?
A) Drug-sensitivity testing, microscopy of cervical mucosa, and blood typing
B) Chorionic villus sampling (CVS), amniocentesis, and preimplantation genetic
testing (PGT)
C) Ultrasound, maternal serum screening, and fetal heart monitoring
D) Glucose tolerance test, Group B strep screening, and rubella titer
Answer: B
Rationale: CVS is performed between weeks 11-14 of pregnancy. Amniocentesis
evaluates amniotic fluid during the second trimester (weeks 15-20). PGT is
performed on the embryo prior to implantation.
Question 4
Which genetic disorder is characterized by the presence of a zygote having one
chromosome with a normal complement of genes and one chromosome with a
missing gene?
A) Klinefelter syndrome
B) Down syndrome
C) Cri du chat syndrome
D) Turner syndrome
Answer: C
Rationale: Cri du chat syndrome ("cry of the cat") is caused by a DNA deletion. It
presents as a microcephalic, low birth-weight baby with a piercing cry.
,Question 5
How can an X-linked recessive disease skip generations?
A) Mothers cannot pass X-linked genes to their sons
B) Females are hemizygous for the X chromosome
C) The disease can be transmitted through female carriers
D) These diseases need only one copy of the gene in females
Answer: C
Rationale: Since females have two X chromosomes, a mother may provide an
unaffected X to a daughter or son. A daughter may not show signs because she
has another X to compensate.
Question 6
What does the term "imprinted gene" refer to?
A) A gene that has been mutated
B) The silenced gene of a gene pair
C) A gene that is always expressed
D) A gene that is only found on the Y chromosome
Answer: B
Rationale: An imprinted gene is one that has been silenced through epigenetic
mechanisms.
Question 7
In which of the following are chromosomal abnormalities most common?
A) Stillbirths
B) Spontaneous abortions
, C) Live births
D) Neonatal deaths
Answer: B
Rationale: Chromosomal abnormalities are most commonly associated with
spontaneous abortions.
Question 8
What is the most common trisomy in live births?
A) Trisomy 13 (Patau syndrome)
B) Trisomy 18 (Edwards syndrome)
C) Trisomy 21 (Down syndrome)
D) Trisomy X
Answer: C
Rationale: Trisomy 21 is the most common trisomy in live births. Trisomy 13 and 18
typically result in death within the first year of life.
Question 9
What is the karyotype for Klinefelter syndrome?
A) 47,XXX
B) 47,XXY
C) 45,X
D) 47,XYY
Answer: B
Rationale: Klinefelter syndrome is characterized by a 47,XXY karyotype. This
condition affects males and is associated with tall stature, gynecomastia, and
infertility.
2026/2027 Update | Comprehensive Exam Questions
with Verified Answers and Detailed Rationales (100%
Fully Solved) | Already Graded A+
SECTION 1: GENETICS & GENOMIC DISORDERS
Question 1
Which type of genetic disease affects males more frequently than females?
A) Autosomal dominant
B) Autosomal recessive
C) X-linked recessive
D) Mitochondrial
Answer: C
Rationale: X-linked recessive disorders affect males more frequently because males
have only one X chromosome. A single recessive mutation on that X chromosome
will be expressed. Females have two X chromosomes, so the presence of a normal
second X can mask the mutation.
Question 2
Chromosomal abnormalities are the leading known cause of which two
conditions?
A) Intellectual disability and fetal miscarriage
B) Respiratory disorders and cardiovascular disease
C) Mental illness and autoimmune disorders
D) Diabetes and hypertension
,Answer: A
Rationale: Chromosomal abnormalities are the leading known cause of intellectual
disability and fetal miscarriage.
Question 3
What are three examples of prenatal diagnostic studies?
A) Drug-sensitivity testing, microscopy of cervical mucosa, and blood typing
B) Chorionic villus sampling (CVS), amniocentesis, and preimplantation genetic
testing (PGT)
C) Ultrasound, maternal serum screening, and fetal heart monitoring
D) Glucose tolerance test, Group B strep screening, and rubella titer
Answer: B
Rationale: CVS is performed between weeks 11-14 of pregnancy. Amniocentesis
evaluates amniotic fluid during the second trimester (weeks 15-20). PGT is
performed on the embryo prior to implantation.
Question 4
Which genetic disorder is characterized by the presence of a zygote having one
chromosome with a normal complement of genes and one chromosome with a
missing gene?
A) Klinefelter syndrome
B) Down syndrome
C) Cri du chat syndrome
D) Turner syndrome
Answer: C
Rationale: Cri du chat syndrome ("cry of the cat") is caused by a DNA deletion. It
presents as a microcephalic, low birth-weight baby with a piercing cry.
,Question 5
How can an X-linked recessive disease skip generations?
A) Mothers cannot pass X-linked genes to their sons
B) Females are hemizygous for the X chromosome
C) The disease can be transmitted through female carriers
D) These diseases need only one copy of the gene in females
Answer: C
Rationale: Since females have two X chromosomes, a mother may provide an
unaffected X to a daughter or son. A daughter may not show signs because she
has another X to compensate.
Question 6
What does the term "imprinted gene" refer to?
A) A gene that has been mutated
B) The silenced gene of a gene pair
C) A gene that is always expressed
D) A gene that is only found on the Y chromosome
Answer: B
Rationale: An imprinted gene is one that has been silenced through epigenetic
mechanisms.
Question 7
In which of the following are chromosomal abnormalities most common?
A) Stillbirths
B) Spontaneous abortions
, C) Live births
D) Neonatal deaths
Answer: B
Rationale: Chromosomal abnormalities are most commonly associated with
spontaneous abortions.
Question 8
What is the most common trisomy in live births?
A) Trisomy 13 (Patau syndrome)
B) Trisomy 18 (Edwards syndrome)
C) Trisomy 21 (Down syndrome)
D) Trisomy X
Answer: C
Rationale: Trisomy 21 is the most common trisomy in live births. Trisomy 13 and 18
typically result in death within the first year of life.
Question 9
What is the karyotype for Klinefelter syndrome?
A) 47,XXX
B) 47,XXY
C) 45,X
D) 47,XYY
Answer: B
Rationale: Klinefelter syndrome is characterized by a 47,XXY karyotype. This
condition affects males and is associated with tall stature, gynecomastia, and
infertility.
