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 compares two human cells and finds that one contains a
nucleus with the same chromosome number as the other but expresses
a very different set of proteins. Which feature best explains how these
genetically similar cells can have different functions?
A. Different mitochondrial DNA sequences in every cell
B. Differential expression of genes within the genome
C. Different numbers of chromosomes in each differentiated cell
D. Complete replacement of DNA during cellular differentiation
,Correct Answer: B. Differential expression of genes within the genome
Rationale: Cells within an organism generally contain the same genome,
but they perform different functions because different subsets of genes
are expressed or silenced. This selective gene expression determines
the proteins produced by a cell. A is not the primary explanation, C is
incorrect because most somatic cells have the same chromosome
number, and D does not occur during normal differentiation.
Question 2
A patient has a mutation that prevents accurate replication of nuclear
DNA. Which cellular process is most directly threatened by this defect?
A. Maintenance of genetic information during cell division
B. Packaging of proteins into secretory vesicles
C. Oxidative phosphorylation within lysosomes
D. Degradation of extracellular collagen
Correct Answer: A. Maintenance of genetic information during cell
division
Rationale: Accurate DNA replication is essential for preserving the
genome as cells divide. Replication errors can produce mutations and
genomic instability. B occurs primarily through the endoplasmic
reticulum and Golgi apparatus, C incorrectly assigns oxidative
phosphorylation to lysosomes, and D is an extracellular matrix process
involving proteases such as matrix metalloproteinases.
Question 3
, A liver cell synthesizes a protein that must be transported outside the
cell. Which sequence of organelles is most directly involved in
producing and secreting this protein?
A. Smooth endoplasmic reticulum → lysosome → nucleus
B. Ribosome on rough endoplasmic reticulum → Golgi apparatus →
secretory vesicle
C. Nucleus → peroxisome → mitochondrion
D. Golgi apparatus → proteasome → lysosome
Correct Answer: B. Ribosome on rough endoplasmic reticulum → Golgi
apparatus → secretory vesicle
Rationale: Proteins destined for secretion are synthesized by ribosomes
attached to the rough endoplasmic reticulum, then modified and sorted
through the Golgi apparatus before being packaged into secretory
vesicles. A, C, and D do not represent the normal secretory pathway.
The proteasome, in particular, primarily degrades ubiquitinated
intracellular proteins rather than packaging secreted proteins.
Question 4
A cell is exposed to a toxic substance that inhibits mitochondrial
oxidative phosphorylation. Which immediate cellular consequence is
most likely?
A. Increased ATP production through the electron transport chain
B. Reduced ATP availability for energy-dependent cellular processes
C. Increased synthesis of extracellular collagen
D. Increased DNA replication caused by excess cellular energy
Correct Answer: B. Reduced ATP availability for energy-dependent
cellular processes
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 compares two human cells and finds that one contains a
nucleus with the same chromosome number as the other but expresses
a very different set of proteins. Which feature best explains how these
genetically similar cells can have different functions?
A. Different mitochondrial DNA sequences in every cell
B. Differential expression of genes within the genome
C. Different numbers of chromosomes in each differentiated cell
D. Complete replacement of DNA during cellular differentiation
,Correct Answer: B. Differential expression of genes within the genome
Rationale: Cells within an organism generally contain the same genome,
but they perform different functions because different subsets of genes
are expressed or silenced. This selective gene expression determines
the proteins produced by a cell. A is not the primary explanation, C is
incorrect because most somatic cells have the same chromosome
number, and D does not occur during normal differentiation.
Question 2
A patient has a mutation that prevents accurate replication of nuclear
DNA. Which cellular process is most directly threatened by this defect?
A. Maintenance of genetic information during cell division
B. Packaging of proteins into secretory vesicles
C. Oxidative phosphorylation within lysosomes
D. Degradation of extracellular collagen
Correct Answer: A. Maintenance of genetic information during cell
division
Rationale: Accurate DNA replication is essential for preserving the
genome as cells divide. Replication errors can produce mutations and
genomic instability. B occurs primarily through the endoplasmic
reticulum and Golgi apparatus, C incorrectly assigns oxidative
phosphorylation to lysosomes, and D is an extracellular matrix process
involving proteases such as matrix metalloproteinases.
Question 3
, A liver cell synthesizes a protein that must be transported outside the
cell. Which sequence of organelles is most directly involved in
producing and secreting this protein?
A. Smooth endoplasmic reticulum → lysosome → nucleus
B. Ribosome on rough endoplasmic reticulum → Golgi apparatus →
secretory vesicle
C. Nucleus → peroxisome → mitochondrion
D. Golgi apparatus → proteasome → lysosome
Correct Answer: B. Ribosome on rough endoplasmic reticulum → Golgi
apparatus → secretory vesicle
Rationale: Proteins destined for secretion are synthesized by ribosomes
attached to the rough endoplasmic reticulum, then modified and sorted
through the Golgi apparatus before being packaged into secretory
vesicles. A, C, and D do not represent the normal secretory pathway.
The proteasome, in particular, primarily degrades ubiquitinated
intracellular proteins rather than packaging secreted proteins.
Question 4
A cell is exposed to a toxic substance that inhibits mitochondrial
oxidative phosphorylation. Which immediate cellular consequence is
most likely?
A. Increased ATP production through the electron transport chain
B. Reduced ATP availability for energy-dependent cellular processes
C. Increased synthesis of extracellular collagen
D. Increased DNA replication caused by excess cellular energy
Correct Answer: B. Reduced ATP availability for energy-dependent
cellular processes
