PCB3023C Final Exam: Cell Biology (FGCU Comprehensive) 2026
|FGCU
1. Which component of the plasma membrane is primarily responsible for its
fluid characteristics at various temperatures?
A. Peripheral proteins
B. Transmembrane channels
C. Glycoproteins
D. Cholesterol
Answer: D
Rationale: Cholesterol acts as a temperature buffer, preventing the membrane from
becoming too fluid at high temperatures and too rigid at low temperatures.
2. What is the primary function of the nucleolus within a eukaryotic cell?
A. DNA replication
B. Protein folding
C. Ribosomal RNA synthesis and ribosome assembly
D. Storage of calcium ions
Answer: C
Rationale: The nucleolus is a dense region in the nucleus dedicated to the synthesis of
rRNA and the assembly of ribosomal subunits.
,3. During which phase of the cell cycle does DNA replication occur?
A. G1 phase
B. M phase
C. G2 phase
D. S phase
Answer: D
Rationale: The S phase (Synthesis phase) is specifically designated for the replication of
nuclear DNA.
4. Which organelle is responsible for the detoxification of drugs and the storage
of calcium ions in muscle cells?
A. Rough Endoplasmic Reticulum
B. Golgi Apparatus
C. Smooth Endoplasmic Reticulum
D. Lysosome
Answer: C
Rationale: The Smooth ER is involved in lipid synthesis, carbohydrate metabolism, calcium
storage (sarcoplasmic reticulum in muscles), and detoxification.
5. A protein that is destined to be secreted from the cell is synthesized where?
A. Free ribosomes in the cytosol
B. Mitochondrial matrix
C. Ribosomes bound to the Rough ER
D. Peroxisomes
Answer: C
Rationale: Secretory proteins are synthesized on ribosomes attached to the Rough ER so
they can be co-translationally imported into the lumen.
, 6. In enzyme kinetics, what does the Km (Michaelis constant) represent?
A. The maximum velocity of the reaction
B. The turnover number of the enzyme
C. The total energy released by the reaction
D. The substrate concentration at half Vmax
Answer: D
Rationale: Km is the substrate concentration at which the reaction rate is half of its
maximum velocity (Vmax); it reflects the affinity of the enzyme for its substrate.
7. Which of the following cytoskeletal elements is composed of actin subunits
and is involved in muscle contraction?
A. Microfilaments
B. Intermediate filaments
C. Microtubules
D. Keratin filaments
Answer: A
Rationale: Microfilaments are made of actin and are essential for cellular movements,
including muscle contraction and cytokinesis.
8. What is the role of the Golgi apparatus in the endomembrane system?
A. Modifying, sorting, and packaging proteins
B. ATP production
C. Synthesizing mRNA
D. Breaking down cellular waste
Answer: A
Rationale: The Golgi receives proteins from the ER, modifies them (e.g., glycosylation), and
sorts them for their final destinations.
|FGCU
1. Which component of the plasma membrane is primarily responsible for its
fluid characteristics at various temperatures?
A. Peripheral proteins
B. Transmembrane channels
C. Glycoproteins
D. Cholesterol
Answer: D
Rationale: Cholesterol acts as a temperature buffer, preventing the membrane from
becoming too fluid at high temperatures and too rigid at low temperatures.
2. What is the primary function of the nucleolus within a eukaryotic cell?
A. DNA replication
B. Protein folding
C. Ribosomal RNA synthesis and ribosome assembly
D. Storage of calcium ions
Answer: C
Rationale: The nucleolus is a dense region in the nucleus dedicated to the synthesis of
rRNA and the assembly of ribosomal subunits.
,3. During which phase of the cell cycle does DNA replication occur?
A. G1 phase
B. M phase
C. G2 phase
D. S phase
Answer: D
Rationale: The S phase (Synthesis phase) is specifically designated for the replication of
nuclear DNA.
4. Which organelle is responsible for the detoxification of drugs and the storage
of calcium ions in muscle cells?
A. Rough Endoplasmic Reticulum
B. Golgi Apparatus
C. Smooth Endoplasmic Reticulum
D. Lysosome
Answer: C
Rationale: The Smooth ER is involved in lipid synthesis, carbohydrate metabolism, calcium
storage (sarcoplasmic reticulum in muscles), and detoxification.
5. A protein that is destined to be secreted from the cell is synthesized where?
A. Free ribosomes in the cytosol
B. Mitochondrial matrix
C. Ribosomes bound to the Rough ER
D. Peroxisomes
Answer: C
Rationale: Secretory proteins are synthesized on ribosomes attached to the Rough ER so
they can be co-translationally imported into the lumen.
, 6. In enzyme kinetics, what does the Km (Michaelis constant) represent?
A. The maximum velocity of the reaction
B. The turnover number of the enzyme
C. The total energy released by the reaction
D. The substrate concentration at half Vmax
Answer: D
Rationale: Km is the substrate concentration at which the reaction rate is half of its
maximum velocity (Vmax); it reflects the affinity of the enzyme for its substrate.
7. Which of the following cytoskeletal elements is composed of actin subunits
and is involved in muscle contraction?
A. Microfilaments
B. Intermediate filaments
C. Microtubules
D. Keratin filaments
Answer: A
Rationale: Microfilaments are made of actin and are essential for cellular movements,
including muscle contraction and cytokinesis.
8. What is the role of the Golgi apparatus in the endomembrane system?
A. Modifying, sorting, and packaging proteins
B. ATP production
C. Synthesizing mRNA
D. Breaking down cellular waste
Answer: A
Rationale: The Golgi receives proteins from the ER, modifies them (e.g., glycosylation), and
sorts them for their final destinations.
