Robbins Basic Pathology
10th Edition
Author(s)Vinay Kumar; MBBS; MD;
FRCPath; Abul K. Abbas; MBBS and
Jon C. Aster; MD; PhD
Print ISBN: 9780323353175
,Question 1
A researcher examines a cell with extensive transcriptional activity. Which nuclear feature would
most strongly indicate that the cell is actively expressing many genes?
A. Predominance of heterochromatin
B. Abundance of euchromatin
C. Complete absence of nucleoli
D. Extensive DNA methylation
Correct Answer: B. Abundance of euchromatin
Rationale: Euchromatin is relatively open and accessible to transcriptional machinery, making it
characteristic of cells with active gene expression. Heterochromatin is more condensed and
,generally less transcriptionally active. Nucleoli are involved in ribosomal RNA production,
while DNA methylation commonly contributes to transcriptional repression.
Question 2
A mutation changes the DNA sequence within the coding region of a gene but does not alter the
amino acid sequence of the protein produced. Which type of mutation most likely occurred?
A. Frameshift mutation
B. Nonsense mutation
C. Missense mutation
D. Silent mutation
Correct Answer: D. Silent mutation
Rationale: A silent mutation changes a nucleotide sequence without changing the encoded
amino acid because multiple codons can specify the same amino acid. A missense mutation
produces a different amino acid, a nonsense mutation creates a premature stop codon, and a
frameshift mutation alters the reading frame.
Question 3
A cell is exposed to a toxic compound that causes accumulation of damaged proteins within the
cytoplasm. Which cellular housekeeping mechanism is primarily responsible for targeting many
such proteins for degradation?
A. Ubiquitin-proteasome system
B. DNA replication
C. Ribosomal protein synthesis
D. Glycolysis
Correct Answer: A. Ubiquitin-proteasome system
Rationale: Misfolded or damaged intracellular proteins can be tagged with ubiquitin and
directed to proteasomes for degradation. DNA replication copies genetic material, ribosomes
synthesize proteins, and glycolysis generates ATP from glucose. These processes do not
primarily remove abnormal intracellular proteins.
Question 4
A cell deprived of nutrients begins degrading portions of its own cytoplasm and organelles to
recycle intracellular components. Which process best explains this response?
A. Exocytosis
B. Autophagy
C. Endocytosis
D. Transcription
Correct Answer: B. Autophagy
Rationale: Autophagy allows cells to sequester and degrade cytoplasmic components, providing
, substrates for recycling and survival during nutrient deprivation. Exocytosis exports substances,
endocytosis internalizes extracellular material, and transcription produces RNA from DNA.
Question 5
A patient develops a disorder caused by impaired lysosomal enzyme activity. Which cellular
consequence would be most likely?
A. Failure of DNA replication
B. Accumulation of undegraded intracellular material
C. Increased synthesis of extracellular collagen
D. Excessive ATP production
Correct Answer: B. Accumulation of undegraded intracellular material
Rationale: Lysosomes contain hydrolytic enzymes that digest macromolecules and cellular
debris. Defective lysosomal function results in accumulation of substrates that cannot be
adequately degraded. DNA replication, collagen synthesis, and ATP generation are distinct
cellular processes.
Question 6
A cell requires large amounts of ATP to maintain ion gradients across its plasma membrane.
Which organelle is primarily responsible for supplying ATP through oxidative phosphorylation?
A. Golgi apparatus
B. Lysosome
C. Mitochondrion
D. Peroxisome
Correct Answer: C. Mitochondrion
Rationale: Mitochondria generate most cellular ATP through oxidative phosphorylation in the
inner mitochondrial membrane. The Golgi modifies and sorts proteins, lysosomes digest cellular
material, and peroxisomes participate in oxidative reactions and lipid metabolism but are not the
principal source of ATP.
Question 7
A toxin interferes with the electron transport chain in mitochondria. Which immediate cellular
effect is most likely?
A. Increased ATP synthesis
B. Reduced proton gradient and impaired ATP production
C. Increased DNA transcription
D. Enhanced extracellular matrix synthesis
Correct Answer: B. Reduced proton gradient and impaired ATP production
Rationale: The electron transport chain establishes a proton gradient across the inner
mitochondrial membrane that drives ATP synthesis. Disruption of electron transport decreases
10th Edition
Author(s)Vinay Kumar; MBBS; MD;
FRCPath; Abul K. Abbas; MBBS and
Jon C. Aster; MD; PhD
Print ISBN: 9780323353175
,Question 1
A researcher examines a cell with extensive transcriptional activity. Which nuclear feature would
most strongly indicate that the cell is actively expressing many genes?
A. Predominance of heterochromatin
B. Abundance of euchromatin
C. Complete absence of nucleoli
D. Extensive DNA methylation
Correct Answer: B. Abundance of euchromatin
Rationale: Euchromatin is relatively open and accessible to transcriptional machinery, making it
characteristic of cells with active gene expression. Heterochromatin is more condensed and
,generally less transcriptionally active. Nucleoli are involved in ribosomal RNA production,
while DNA methylation commonly contributes to transcriptional repression.
Question 2
A mutation changes the DNA sequence within the coding region of a gene but does not alter the
amino acid sequence of the protein produced. Which type of mutation most likely occurred?
A. Frameshift mutation
B. Nonsense mutation
C. Missense mutation
D. Silent mutation
Correct Answer: D. Silent mutation
Rationale: A silent mutation changes a nucleotide sequence without changing the encoded
amino acid because multiple codons can specify the same amino acid. A missense mutation
produces a different amino acid, a nonsense mutation creates a premature stop codon, and a
frameshift mutation alters the reading frame.
Question 3
A cell is exposed to a toxic compound that causes accumulation of damaged proteins within the
cytoplasm. Which cellular housekeeping mechanism is primarily responsible for targeting many
such proteins for degradation?
A. Ubiquitin-proteasome system
B. DNA replication
C. Ribosomal protein synthesis
D. Glycolysis
Correct Answer: A. Ubiquitin-proteasome system
Rationale: Misfolded or damaged intracellular proteins can be tagged with ubiquitin and
directed to proteasomes for degradation. DNA replication copies genetic material, ribosomes
synthesize proteins, and glycolysis generates ATP from glucose. These processes do not
primarily remove abnormal intracellular proteins.
Question 4
A cell deprived of nutrients begins degrading portions of its own cytoplasm and organelles to
recycle intracellular components. Which process best explains this response?
A. Exocytosis
B. Autophagy
C. Endocytosis
D. Transcription
Correct Answer: B. Autophagy
Rationale: Autophagy allows cells to sequester and degrade cytoplasmic components, providing
, substrates for recycling and survival during nutrient deprivation. Exocytosis exports substances,
endocytosis internalizes extracellular material, and transcription produces RNA from DNA.
Question 5
A patient develops a disorder caused by impaired lysosomal enzyme activity. Which cellular
consequence would be most likely?
A. Failure of DNA replication
B. Accumulation of undegraded intracellular material
C. Increased synthesis of extracellular collagen
D. Excessive ATP production
Correct Answer: B. Accumulation of undegraded intracellular material
Rationale: Lysosomes contain hydrolytic enzymes that digest macromolecules and cellular
debris. Defective lysosomal function results in accumulation of substrates that cannot be
adequately degraded. DNA replication, collagen synthesis, and ATP generation are distinct
cellular processes.
Question 6
A cell requires large amounts of ATP to maintain ion gradients across its plasma membrane.
Which organelle is primarily responsible for supplying ATP through oxidative phosphorylation?
A. Golgi apparatus
B. Lysosome
C. Mitochondrion
D. Peroxisome
Correct Answer: C. Mitochondrion
Rationale: Mitochondria generate most cellular ATP through oxidative phosphorylation in the
inner mitochondrial membrane. The Golgi modifies and sorts proteins, lysosomes digest cellular
material, and peroxisomes participate in oxidative reactions and lipid metabolism but are not the
principal source of ATP.
Question 7
A toxin interferes with the electron transport chain in mitochondria. Which immediate cellular
effect is most likely?
A. Increased ATP synthesis
B. Reduced proton gradient and impaired ATP production
C. Increased DNA transcription
D. Enhanced extracellular matrix synthesis
Correct Answer: B. Reduced proton gradient and impaired ATP production
Rationale: The electron transport chain establishes a proton gradient across the inner
mitochondrial membrane that drives ATP synthesis. Disruption of electron transport decreases
