Foundational Biomedical Science Integration
Exam 2026 Edition Verified Answers with
Detailed Rationales
1.
A 24-year-old man has a mutation that prevents the normal
insertion of newly synthesized proteins into the endoplasmic
reticulum. Which cellular process is most directly impaired?
A. Glycolysis
B. Protein translocation into the rough endoplasmic reticulum
C. DNA replication
D. Fatty acid β-oxidation
Answer: B. Protein translocation into the rough endoplasmic
reticulum
The rough endoplasmic reticulum receives proteins destined for
secretion, lysosomes, or insertion into cellular membranes.
Ribosomes synthesize these proteins and direct them into the ER
through translocation machinery. Glycolysis and β-oxidation
occur primarily in the cytosol and mitochondria, respectively.
,2.
A researcher inhibits mitochondrial ATP synthase in a cell.
Which immediate effect is most likely?
A. Increased oxidative phosphorylation
B. Increased mitochondrial ATP production
C. Reduced ATP production despite continued electron
transport
D. Increased conversion of pyruvate to acetyl-CoA
Answer: C. Reduced ATP production despite continued
electron transport
ATP synthase uses the proton gradient generated by the
electron transport chain to produce ATP. Inhibition prevents
oxidative phosphorylation and eventually causes proton
accumulation that also inhibits electron transport. Pyruvate
oxidation would decrease as mitochondrial energy production
becomes impaired.
3.
A patient develops severe hemolytic anemia after exposure to
an oxidizing medication. Laboratory testing reveals decreased
glutathione levels. Which enzyme is most likely deficient?
,A. Pyruvate kinase
B. Hexokinase
C. Glucose-6-phosphate dehydrogenase
D. Lactate dehydrogenase
Answer: C. Glucose-6-phosphate dehydrogenase
Glucose-6-phosphate dehydrogenase generates NADPH through
the pentose phosphate pathway. NADPH maintains glutathione
in its reduced form, allowing erythrocytes to neutralize reactive
oxygen species. Deficiency predisposes red blood cells to
oxidative hemolysis.
4.
A 7-year-old child has recurrent infections with encapsulated
bacteria. Laboratory studies show absent mature B cells and
markedly decreased immunoglobulin levels. Which cellular
defect best explains this condition?
A. Failure of T-cell receptor rearrangement
B. Failure of neutrophil oxidative burst
C. Failure of B-cell maturation
D. Failure of complement synthesis
Answer: C. Failure of B-cell maturation
, Defective B-cell maturation causes profound
hypogammaglobulinemia and susceptibility to encapsulated
organisms. Antibody-mediated opsonization is particularly
important for clearing these bacteria.
5.
A patient with chronic kidney disease develops normocytic
anemia. Which mechanism best explains this finding?
A. Reduced intestinal iron absorption
B. Increased erythrocyte destruction
C. Decreased erythropoietin production
D. Increased folate degradation
Answer: C. Decreased erythropoietin production
Renal peritubular interstitial cells produce erythropoietin in
response to tissue hypoxia. Chronic kidney disease reduces
erythropoietin production, resulting in decreased erythropoiesis
and typically a normocytic, normochromic anemia.
6.
A researcher studies a mutation that changes a single
nucleotide but does not alter the amino acid sequence of the
encoded protein. What type of mutation has occurred?
Exam 2026 Edition Verified Answers with
Detailed Rationales
1.
A 24-year-old man has a mutation that prevents the normal
insertion of newly synthesized proteins into the endoplasmic
reticulum. Which cellular process is most directly impaired?
A. Glycolysis
B. Protein translocation into the rough endoplasmic reticulum
C. DNA replication
D. Fatty acid β-oxidation
Answer: B. Protein translocation into the rough endoplasmic
reticulum
The rough endoplasmic reticulum receives proteins destined for
secretion, lysosomes, or insertion into cellular membranes.
Ribosomes synthesize these proteins and direct them into the ER
through translocation machinery. Glycolysis and β-oxidation
occur primarily in the cytosol and mitochondria, respectively.
,2.
A researcher inhibits mitochondrial ATP synthase in a cell.
Which immediate effect is most likely?
A. Increased oxidative phosphorylation
B. Increased mitochondrial ATP production
C. Reduced ATP production despite continued electron
transport
D. Increased conversion of pyruvate to acetyl-CoA
Answer: C. Reduced ATP production despite continued
electron transport
ATP synthase uses the proton gradient generated by the
electron transport chain to produce ATP. Inhibition prevents
oxidative phosphorylation and eventually causes proton
accumulation that also inhibits electron transport. Pyruvate
oxidation would decrease as mitochondrial energy production
becomes impaired.
3.
A patient develops severe hemolytic anemia after exposure to
an oxidizing medication. Laboratory testing reveals decreased
glutathione levels. Which enzyme is most likely deficient?
,A. Pyruvate kinase
B. Hexokinase
C. Glucose-6-phosphate dehydrogenase
D. Lactate dehydrogenase
Answer: C. Glucose-6-phosphate dehydrogenase
Glucose-6-phosphate dehydrogenase generates NADPH through
the pentose phosphate pathway. NADPH maintains glutathione
in its reduced form, allowing erythrocytes to neutralize reactive
oxygen species. Deficiency predisposes red blood cells to
oxidative hemolysis.
4.
A 7-year-old child has recurrent infections with encapsulated
bacteria. Laboratory studies show absent mature B cells and
markedly decreased immunoglobulin levels. Which cellular
defect best explains this condition?
A. Failure of T-cell receptor rearrangement
B. Failure of neutrophil oxidative burst
C. Failure of B-cell maturation
D. Failure of complement synthesis
Answer: C. Failure of B-cell maturation
, Defective B-cell maturation causes profound
hypogammaglobulinemia and susceptibility to encapsulated
organisms. Antibody-mediated opsonization is particularly
important for clearing these bacteria.
5.
A patient with chronic kidney disease develops normocytic
anemia. Which mechanism best explains this finding?
A. Reduced intestinal iron absorption
B. Increased erythrocyte destruction
C. Decreased erythropoietin production
D. Increased folate degradation
Answer: C. Decreased erythropoietin production
Renal peritubular interstitial cells produce erythropoietin in
response to tissue hypoxia. Chronic kidney disease reduces
erythropoietin production, resulting in decreased erythropoiesis
and typically a normocytic, normochromic anemia.
6.
A researcher studies a mutation that changes a single
nucleotide but does not alter the amino acid sequence of the
encoded protein. What type of mutation has occurred?
