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Section 1: Cellular & Genetic Foundations Review
Q1: A 45-year-old smoker develops squamous metaplasia in the tracheal epithelium.
The nurse explaining this finding to a student emphasizes that metaplasia represents:
A. Disorganized, precancerous cellular changes that always progress to cancer
B. A reversible adaptation where one mature cell type replaces another [CORRECT]
C. Irreversible cell death with tissue replacement by fibrous scar
D. Abnormal cellular enlargement in response to increased workload
Correct Answer: B
Rationale: The best way to think about metaplasia is as a reversible change where a
mature cell type better suited to handle stress replaces the original cell type—like the
respiratory epithelium changing from ciliated columnar to squamous to withstand
cigarette smoke. Remember that it's reversible if the stimulus is removed, and while it
can be a precursor to dysplasia, it doesn't always become cancer. You'll see this tested
because students often confuse it with dysplasia, which is the disorganized, potentially
precancerous change described in option A.
Q2: A patient with a myocardial infarction shows coagulative necrosis on biopsy. The
key pathologic feature distinguishing coagulative necrosis from other types is:
A. Complete liquefaction of tissue architecture
B. Preservation of tissue outline with loss of nuclear detail [CORRECT]
,C. Caseous, cheese-like appearance with granulomatous inflammation
D. Calcium deposition and fat saponification
Correct Answer: B
Rationale: What ties this together is understanding that coagulative necrosis—classic in
ischemic injury to solid organs like heart, kidney, and spleen—preserves the cellular
architecture for days because denatured enzymes can't break down the tissue, even
though nuclei disappear. The "ghost outline" is what you're looking for. Liquefaction (A)
happens in brain infarcts, caseous necrosis (C) in TB, and fat necrosis with calcium (D)
in pancreatitis or breast trauma.
Q3: A 28-year-old woman develops dry gangrene in her toes due to peripheral arterial
disease. The pathophysiologic process underlying dry gangrene involves:
A. Rapid bacterial infection with liquefactive tissue destruction
B. Coagulative necrosis with desiccation and mummification [CORRECT]
C. Gas-forming organisms creating tissue crepitus
D. Enzymatic fat digestion with calcium soap formation
Correct Answer: B
Rationale: The key here is recognizing that dry gangrene results from slow, chronic
ischemia without significant bacterial infection—think of it as mummified tissue. The
blood supply is so compromised that the tissue simply dries out and shrivels. Wet
gangrene (A) involves infection and liquefaction, gas gangrene (C) involves clostridial
organisms with gas production, and fat necrosis (D) is specific to enzymatic injury in
pancreatitis.
Q4: A patient with chronic hepatitis develops hepatocellular carcinoma. The molecular
mechanism most likely involved in this malignant transformation is:
,A. Activation of tumor suppressor genes p53 and Rb
B. Inactivation of tumor suppressor genes or activation of oncogenes [CORRECT]
C. Increased apoptosis of damaged hepatocytes
D. Enhanced DNA repair mechanisms in infected cells
Correct Answer: B
Rationale: The best way to think about carcinogenesis is that cancer develops when the
normal checks and balances fail—either tumor suppressor genes (the "brakes") get
turned off, or oncogenes (the "accelerators") get stuck on. In hepatitis-related HCC,
chronic inflammation and oxidative damage lead to mutations. Remember that p53 and
Rb being activated (A) would actually prevent cancer, and increased apoptosis (C) or
enhanced repair (D) would protect against malignancy, not cause it.
Q5: A newborn with Down syndrome has which characteristic chromosomal finding?
A. 45,X karyotype with missing sex chromosome
B. Trisomy 21 with three copies of chromosome 21 [CORRECT]
C. 47,XXY karyotype with extra sex chromosome
D. Deletion of the short arm of chromosome 5
Correct Answer: B
Rationale: Down syndrome is the classic trisomy 21—three copies of chromosome 21
instead of two. You'll see this tested because it's the most common chromosomal
cause of intellectual disability. The 45,X (A) is Turner syndrome, 47,XXY (C) is Klinefelter
syndrome, and the deletion on chromosome 5 (D) causes cri-du-chat syndrome.
Remember that advanced maternal age increases risk of trisomies.
Q6: A patient with cystic fibrosis has recurrent pulmonary infections and pancreatic
insufficiency. The genetic basis for this disorder is:
, A. Autosomal dominant mutation in the fibrillin gene
B. Autosomal recessive mutation in the CFTR gene on chromosome 7 [CORRECT]
C. X-linked recessive mutation affecting chloride channels
D. Trinucleotide repeat expansion in the huntingtin gene
Correct Answer: B
Rationale: Cystic fibrosis follows autosomal recessive inheritance—you need two copies
of the mutated CFTR gene. The CFTR protein is a chloride channel, and when defective,
it leads to thick, sticky secretions in lungs and pancreas. Autosomal dominant fibrillin
mutations (A) cause Marfan syndrome, X-linked recessive (C) would affect mostly
males, and trinucleotide repeats (D) cause Huntington's disease. What ties this together
is remembering that CF is one of the most common lethal autosomal recessive
diseases in Caucasian populations.
Q7: A 25-year-old man with a family history of sudden cardiac death is diagnosed with
hypertrophic cardiomyopathy. The inheritance pattern is:
A. Autosomal recessive requiring both parents to be carriers
B. Autosomal dominant with variable penetrance [CORRECT]
C. X-linked recessive affecting only males
D. Mitochondrial inheritance from the mother only
Correct Answer: B
Rationale: Hypertrophic cardiomyopathy is autosomal dominant—if you have the gene,
you have a 50% chance of passing it to each child. The variable penetrance means not
everyone with the gene shows the same severity, which explains why some family
members might have mild disease while others have sudden death. It's not recessive
(A), not X-linked (C), and not mitochondrial (D). You'll see this tested because it's a
common cause of sudden death in young athletes.