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QUESTION 1
A cell is exposed to a toxin that damages mitochondrial DNA. Which cellular
function will be most immediately impaired?
A) Protein synthesis
B) ATP production
C) Lipid synthesis
D) DNA replication
Answer: B
Rationale: Mitochondria are the primary site of oxidative phosphorylation and
ATP production. Damage to mitochondrial DNA impairs the electron transport
chain, reducing ATP synthesis. Cells with high energy demands are most
vulnerable.
QUESTION 2
Which type of cellular adaptation involves an increase in the number of cells in a
tissue?
A) Hypertrophy
B) Hyperplasia
C) Atrophy
D) Metaplasia
Answer: B
Rationale: Hyperplasia is an increase in cell number due to increased mitotic
division. It occurs in tissues capable of mitosis. Hypertrophy is an increase in cell
size, while metaplasia is a change in cell type.
QUESTION 3
A patient with chronic hypoxia develops increased red blood cell production. This
is an example of:
,A) Physiologic hypertrophy
B) Pathologic hyperplasia
C) Physiologic hyperplasia
D) Metaplasia
Answer: C
Rationale: Increased erythropoietin production in response to hypoxia stimulates
bone marrow hyperplasia, increasing RBC production. This is a compensatory,
physiologic response.
QUESTION 4
Which cellular change is considered a reversible response to injury?
A) Necrosis
B) Apoptosis
C) Cellular swelling
D) Karyolysis
Answer: C
Rationale: Cellular swelling is the earliest and most reversible manifestation of cell
injury. It results from failure of the Na+/K+ pump, leading to influx of sodium and
water.
QUESTION 5
A patient with chronic GERD develops intestinal-type epithelium in the distal
esophagus. This is an example of:
A) Hypertrophy
B) Hyperplasia
C) Metaplasia
D) Dysplasia
Answer: C
Rationale: Barrett's esophagus is a classic example of metaplasia where one adult
cell type is replaced by another in response to chronic irritation from gastric acid.
QUESTION 6
Which characteristic indicates irreversible cell injury?
A) Cellular swelling
B) Decreased ATP production
C) Mitochondrial dysfunction with amorphous densities
D) Detachment of ribosomes from endoplasmic reticulum
Answer: C
,Rationale: Irreversible cell injury is marked by severe mitochondrial damage,
profound membrane damage, and nuclear changes. Cellular swelling and decreased
ATP are reversible changes.
QUESTION 7
Which gene mutation would most likely lead to uncontrolled cell proliferation?
A) Mutation in a tumor suppressor gene causing loss of function
B) Mutation in a structural protein gene
C) Mutation in a mitochondrial gene
D) Mutation in a hemoglobin gene
Answer: A
Rationale: Tumor suppressor genes normally inhibit cell division or promote
apoptosis. Loss-of-function mutations remove these brakes on cell proliferation,
leading to uncontrolled growth.
QUESTION 8
A child is born with an autosomal recessive disorder. Which statement about the
parents is correct?
A) Both parents must have the disease
B) Both parents are heterozygous carriers of the mutated gene
C) One parent has the disease and one is a carrier
D) Neither parent carries the gene
Answer: B
Rationale: In autosomal recessive inheritance, both parents must carry one copy of
the mutated gene. The child inherits two mutated copies. Carriers are typically
asymptomatic.
QUESTION 9
Which type of genetic disorder results from a mutation in mitochondrial DNA?
A) Autosomal dominant disorder
B) Autosomal recessive disorder
C) X-linked disorder
D) Mitochondrial disorder, inherited exclusively from the mother
Answer: D
Rationale: Mitochondrial DNA is inherited solely from the mother because sperm
mitochondria are destroyed after fertilization. Disorders like MELAS syndrome
follow maternal inheritance patterns.
QUESTION 10
Which chromosomal abnormality is characteristic of Down syndrome?
, A) Monosomy X
B) Trisomy 21
C) Trisomy 18
D) Trisomy 13
Answer: B
Rationale: Down syndrome results from trisomy of chromosome 21. It is the most
common chromosomal disorder, associated with advanced maternal age.
QUESTION 11
What is the primary difference between innate and adaptive immunity?
A) Innate immunity is slow; adaptive immunity is rapid
B) Innate immunity is non-specific and immediate; adaptive immunity is highly
specific with immunological memory
C) Innate immunity involves T cells; adaptive immunity involves B cells only
D) There is no difference
Answer: B
Rationale: Innate immunity responds rapidly and non-specifically. Adaptive
immunity is slower but highly specific to a particular pathogen and creates
memory for faster response upon re-exposure.
QUESTION 12
Which immunoglobulin is the primary mediator of allergic (Type I
hypersensitivity) reactions?
A) IgG
B) IgA
C) IgM
D) IgE
Answer: D
Rationale: IgE binds to mast cells and basophils. Upon re-exposure to the allergen,
cross-linking of IgE triggers degranulation, releasing histamine and other
mediators causing allergic symptoms.
QUESTION 13
A patient receives a mismatched blood transfusion and develops acute hemolysis.
This is an example of which type of hypersensitivity reaction?
A) Type I
B) Type II
C) Type III
D) Type IV
Answer: B