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 cultured human cell is examined during interphase. Investigators
determine that its DNA is packaged with proteins into chromatin within
the nucleus. Which structure is the fundamental repeating unit
responsible for organizing nuclear DNA?
A. Ribosome
B. Nucleosome
C. Centrosome
D. Proteasome
,Correct Answer: B. Nucleosome
Rationale: The nucleosome is the basic structural unit of chromatin and
consists of DNA wrapped around a core of histone proteins. Ribosomes
synthesize proteins, centrosomes organize microtubules, and
proteasomes degrade proteins. Proper chromatin organization allows
DNA to be efficiently packaged while remaining accessible for
replication and transcription.
Question 2
A researcher studies a cell that is actively synthesizing large amounts of
protein for secretion. Which organelle is expected to be especially
prominent in this cell?
A. Smooth endoplasmic reticulum
B. Rough endoplasmic reticulum
C. Peroxisome
D. Lysosome
Correct Answer: B. Rough endoplasmic reticulum
Rationale: The rough endoplasmic reticulum contains ribosomes and is
responsible for synthesis of proteins destined for secretion,
incorporation into membranes, or delivery to certain organelles.
Smooth endoplasmic reticulum is more involved in lipid synthesis and
detoxification. Peroxisomes participate in oxidative reactions, whereas
lysosomes digest intracellular material.
Question 3
, A cell experiences a temporary reduction in oxygen availability but
recovers completely when blood flow is restored. During the period of
oxygen deprivation, which cellular process is most directly impaired?
A. Oxidative phosphorylation
B. DNA transcription by RNA polymerase
C. Lysosomal digestion
D. Ribosomal assembly in the nucleolus
Correct Answer: A. Oxidative phosphorylation
Rationale: Mitochondria require oxygen as the terminal electron
acceptor for oxidative phosphorylation, making oxygen deprivation
rapidly impair ATP generation. Transcription, lysosomal digestion, and
ribosomal assembly may eventually be affected by energy depletion,
but they are not the primary process directly dependent on oxygen.
Reduced ATP availability is a central consequence of impaired
mitochondrial function.
Question 4
A patient has a mutation in a gene that encodes a membrane receptor
for an extracellular growth factor. The receptor cannot transmit signals
after binding its ligand. Which cellular function is most directly
affected?
A. Signal transduction regulating cellular responses
B. DNA packaging into nucleosomes
C. Degradation of damaged proteins by proteasomes
D. Oxidation of fatty acids in peroxisomes
Correct Answer: A. Signal transduction regulating cellular responses
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 cultured human cell is examined during interphase. Investigators
determine that its DNA is packaged with proteins into chromatin within
the nucleus. Which structure is the fundamental repeating unit
responsible for organizing nuclear DNA?
A. Ribosome
B. Nucleosome
C. Centrosome
D. Proteasome
,Correct Answer: B. Nucleosome
Rationale: The nucleosome is the basic structural unit of chromatin and
consists of DNA wrapped around a core of histone proteins. Ribosomes
synthesize proteins, centrosomes organize microtubules, and
proteasomes degrade proteins. Proper chromatin organization allows
DNA to be efficiently packaged while remaining accessible for
replication and transcription.
Question 2
A researcher studies a cell that is actively synthesizing large amounts of
protein for secretion. Which organelle is expected to be especially
prominent in this cell?
A. Smooth endoplasmic reticulum
B. Rough endoplasmic reticulum
C. Peroxisome
D. Lysosome
Correct Answer: B. Rough endoplasmic reticulum
Rationale: The rough endoplasmic reticulum contains ribosomes and is
responsible for synthesis of proteins destined for secretion,
incorporation into membranes, or delivery to certain organelles.
Smooth endoplasmic reticulum is more involved in lipid synthesis and
detoxification. Peroxisomes participate in oxidative reactions, whereas
lysosomes digest intracellular material.
Question 3
, A cell experiences a temporary reduction in oxygen availability but
recovers completely when blood flow is restored. During the period of
oxygen deprivation, which cellular process is most directly impaired?
A. Oxidative phosphorylation
B. DNA transcription by RNA polymerase
C. Lysosomal digestion
D. Ribosomal assembly in the nucleolus
Correct Answer: A. Oxidative phosphorylation
Rationale: Mitochondria require oxygen as the terminal electron
acceptor for oxidative phosphorylation, making oxygen deprivation
rapidly impair ATP generation. Transcription, lysosomal digestion, and
ribosomal assembly may eventually be affected by energy depletion,
but they are not the primary process directly dependent on oxygen.
Reduced ATP availability is a central consequence of impaired
mitochondrial function.
Question 4
A patient has a mutation in a gene that encodes a membrane receptor
for an extracellular growth factor. The receptor cannot transmit signals
after binding its ligand. Which cellular function is most directly
affected?
A. Signal transduction regulating cellular responses
B. DNA packaging into nucleosomes
C. Degradation of damaged proteins by proteasomes
D. Oxidation of fatty acids in peroxisomes
Correct Answer: A. Signal transduction regulating cellular responses
