Page 1 of 123
Essential Cell Biology, 5th Edition, by Bruce
Alberts, Exam 4 Latest Update With Multiple,
Correctly Answered Questions |Single &
Multiple choice and essays| PACKAGE
BUNDL
1. Which cytoskeletal filament is most resistant to mechanical
stress and forms the nuclear lamina?
a) Microtubules
b) Actin filaments
c) Intermediate filaments
,Page 2 of 123
d) Septins
Answer: c – Intermediate filaments provide tensile strength
and form the nuclear lamina (p. 569).
2. The centrosome nucleates microtubules via which protein
complex?
a) Arp2/3
b) γ-tubulin ring complex
c) Formin
d) Kinesin
Answer: b – γ-TuRC is the microtubule nucleator at
centrosomes (p. 584).
3. Which motor protein moves toward the plus end of
microtubules?
a) Dynein
b) Kinesin-1
c) Myosin II
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d) Tropomyosin
Answer: b – Conventional kinesin moves to plus end (p. 594).
4. A patient has defective dynein in cilia. Which symptom is
most likely?
a) Muscular dystrophy
b) Chronic respiratory infections
c) Hemophilia
d) Diabetes
Answer: b – Impaired ciliary clearance leads to respiratory
infections (Kartagener syndrome) (p. 597).
5. During mitosis, which structure directly attaches to
kinetochores?
a) Aster microtubules
b) Kinetochore microtubules
c) Interpolar microtubules
d) Astral microtubules
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Answer: b – Kinetochore MTs connect spindle poles to
chromosomes (p. 626).
6. Cyclin-dependent kinase (CDK) activity is primarily
regulated by:
a) Phosphorylation alone
b) Cyclin binding + phosphorylation
c) Proteasome degradation
d) Calcium binding
Answer: b – CDK requires cyclin binding and proper
phosphorylation state (p. 615).
7. Which event triggers anaphase?
a) Activation of separase by APC/C
b) Degradation of cyclin B
c) Cohesin phosphorylation
d) Kinetochore attachment
Answer: a – APC/C ubiquitinates securin, freeing separase to
cleave cohesin (p. 630).
Essential Cell Biology, 5th Edition, by Bruce
Alberts, Exam 4 Latest Update With Multiple,
Correctly Answered Questions |Single &
Multiple choice and essays| PACKAGE
BUNDL
1. Which cytoskeletal filament is most resistant to mechanical
stress and forms the nuclear lamina?
a) Microtubules
b) Actin filaments
c) Intermediate filaments
,Page 2 of 123
d) Septins
Answer: c – Intermediate filaments provide tensile strength
and form the nuclear lamina (p. 569).
2. The centrosome nucleates microtubules via which protein
complex?
a) Arp2/3
b) γ-tubulin ring complex
c) Formin
d) Kinesin
Answer: b – γ-TuRC is the microtubule nucleator at
centrosomes (p. 584).
3. Which motor protein moves toward the plus end of
microtubules?
a) Dynein
b) Kinesin-1
c) Myosin II
,Page 3 of 123
d) Tropomyosin
Answer: b – Conventional kinesin moves to plus end (p. 594).
4. A patient has defective dynein in cilia. Which symptom is
most likely?
a) Muscular dystrophy
b) Chronic respiratory infections
c) Hemophilia
d) Diabetes
Answer: b – Impaired ciliary clearance leads to respiratory
infections (Kartagener syndrome) (p. 597).
5. During mitosis, which structure directly attaches to
kinetochores?
a) Aster microtubules
b) Kinetochore microtubules
c) Interpolar microtubules
d) Astral microtubules
, Page 4 of 123
Answer: b – Kinetochore MTs connect spindle poles to
chromosomes (p. 626).
6. Cyclin-dependent kinase (CDK) activity is primarily
regulated by:
a) Phosphorylation alone
b) Cyclin binding + phosphorylation
c) Proteasome degradation
d) Calcium binding
Answer: b – CDK requires cyclin binding and proper
phosphorylation state (p. 615).
7. Which event triggers anaphase?
a) Activation of separase by APC/C
b) Degradation of cyclin B
c) Cohesin phosphorylation
d) Kinetochore attachment
Answer: a – APC/C ubiquitinates securin, freeing separase to
cleave cohesin (p. 630).
