BSC 1010 Final Exam Review 2027 | Practice Questions
& Correct Answers | Detailed Rationales
1. Put the steps of the process of signal transduction in the order they occur:
1) A conformational change in the signal-receptor complex activates an enzyme.
2) Protein kinases are activated.
3) A signal molecule binds to a receptor.
4) Target proteins are phosphorylated.
Second messenger molecules are released.
A) 3,1,2,5,4
B) 3,1,5,2,4
C) 1,3,5,2,4
D) 3,5,1,2,4
Answer: B
Rationale: Signal binds receptor → conformational change activates enzyme → second messengers
released → kinases activated → target proteins phosphorylated.
2. Integrins are integral membrane proteins. They are often attached to:
A) Nuclear pores
B) Cytoskeletal proteins and proteins in the extracellular matrix
C) Ribosomes
D) Golgi vesicles
Answer: B
Rationale: Integrins connect the extracellular matrix to the cytoskeleton, mediating cell adhesion and
signaling.
,3. Phosphorylation cascades involving a series of protein kinases are useful for cellular signal
transduction because they:
A) Terminate the signal quickly
B) Amplify the original signal many times
C) Prevent cross-talk between pathways
D) Decrease the number of active proteins
Answer: B
Rationale: Each kinase activates multiple downstream targets, amplifying the signal exponentially.
4. The receptors for steroid hormones are located inside the cell instead of on the membrane
surface like most other signal receptors. This is NOT a problem for steroids because:
A) Steroids are water-soluble
B) Steroid hormones are lipid soluble, so they can readily diffuse through the lipid bilayer of the cell
membrane
C) Steroids are actively transported into the cell
D) Steroids bind to membrane receptors first
Answer: B
Rationale: Lipid-soluble steroids diffuse through the plasma membrane and bind intracellular receptors.
5. Which statement describes how the molecular composition of a plant cell wall compares with
the extracellular matrix of animal cells?
A) Both are composed primarily of proteins
B) Plant cell wall fibers consist primarily of carbohydrates; ECM fibers are dominated by proteins
C) Plant cell walls contain only lipids
D) Animal ECM contains cellulose
Answer: B
Rationale: Plant cell walls are made of cellulose (carbohydrate); animal ECM is rich in collagen (protein).
,6. The structure that anchors adjacent epithelial cells via their cytoskeleton is the:
A) Tight junction
B) Gap junction
C) Desmosome
D) Plasmodesma
Answer: C
Rationale: Desmosomes are anchoring junctions that connect intermediate filaments of adjacent cells.
7. Activated signal receptors on the plasma membrane can carry out which two activities?
A) Synthesize ATP; replicate DNA
B) Catalyze receptor phosphorylation; activate G proteins
C) Degrade hormones; transport ions
D) Store calcium; produce cAMP
Answer: B
Rationale: Activated receptors can autophosphorylate or activate G proteins to propagate signals.
8. Different cell types can respond differently to the same signaling molecule because:
A) The signal molecule is different in each cell
B) Each cell type converts the signal to a different metabolite
C) Receptors are identical in all cells
D) Cells do not respond to signals
Answer: B
Rationale: Different cells have different signal transduction pathways and target proteins.
9. When a lipid-soluble hormone enters a cell and binds a receptor, what happens to the receptor?
A) It is degraded immediately
B) It enters the nucleus and activates genes
C) It remains in the cytoplasm
, D) It is exported from the cell
Answer: B
Rationale: The hormone-receptor complex translocates to the nucleus and acts as a transcription factor.
10. Signaling pathways always work in complete isolation from one another.
A) True
B) False
Answer: B
Rationale: Signaling pathways cross-talk and integrate signals from multiple sources.
11. In eukaryotic cells, chromosomes are composed of:
A) RNA and lipids
B) DNA and proteins
C) Only DNA
D) Only proteins
Answer: B
Rationale: Chromosomes consist of DNA wrapped around histone proteins.
12. Forms of the Ras protein found in tumors would cause which of the following?
A) Cell cycle arrest
B) DNA replication to be hyperactive
C) Apoptosis
D) DNA repair
Answer: B
Rationale: Mutated Ras is constitutively active, driving uncontrolled cell proliferation.
13. The mitotic spindle is a microtubular structure that is involved in:
& Correct Answers | Detailed Rationales
1. Put the steps of the process of signal transduction in the order they occur:
1) A conformational change in the signal-receptor complex activates an enzyme.
2) Protein kinases are activated.
3) A signal molecule binds to a receptor.
4) Target proteins are phosphorylated.
Second messenger molecules are released.
A) 3,1,2,5,4
B) 3,1,5,2,4
C) 1,3,5,2,4
D) 3,5,1,2,4
Answer: B
Rationale: Signal binds receptor → conformational change activates enzyme → second messengers
released → kinases activated → target proteins phosphorylated.
2. Integrins are integral membrane proteins. They are often attached to:
A) Nuclear pores
B) Cytoskeletal proteins and proteins in the extracellular matrix
C) Ribosomes
D) Golgi vesicles
Answer: B
Rationale: Integrins connect the extracellular matrix to the cytoskeleton, mediating cell adhesion and
signaling.
,3. Phosphorylation cascades involving a series of protein kinases are useful for cellular signal
transduction because they:
A) Terminate the signal quickly
B) Amplify the original signal many times
C) Prevent cross-talk between pathways
D) Decrease the number of active proteins
Answer: B
Rationale: Each kinase activates multiple downstream targets, amplifying the signal exponentially.
4. The receptors for steroid hormones are located inside the cell instead of on the membrane
surface like most other signal receptors. This is NOT a problem for steroids because:
A) Steroids are water-soluble
B) Steroid hormones are lipid soluble, so they can readily diffuse through the lipid bilayer of the cell
membrane
C) Steroids are actively transported into the cell
D) Steroids bind to membrane receptors first
Answer: B
Rationale: Lipid-soluble steroids diffuse through the plasma membrane and bind intracellular receptors.
5. Which statement describes how the molecular composition of a plant cell wall compares with
the extracellular matrix of animal cells?
A) Both are composed primarily of proteins
B) Plant cell wall fibers consist primarily of carbohydrates; ECM fibers are dominated by proteins
C) Plant cell walls contain only lipids
D) Animal ECM contains cellulose
Answer: B
Rationale: Plant cell walls are made of cellulose (carbohydrate); animal ECM is rich in collagen (protein).
,6. The structure that anchors adjacent epithelial cells via their cytoskeleton is the:
A) Tight junction
B) Gap junction
C) Desmosome
D) Plasmodesma
Answer: C
Rationale: Desmosomes are anchoring junctions that connect intermediate filaments of adjacent cells.
7. Activated signal receptors on the plasma membrane can carry out which two activities?
A) Synthesize ATP; replicate DNA
B) Catalyze receptor phosphorylation; activate G proteins
C) Degrade hormones; transport ions
D) Store calcium; produce cAMP
Answer: B
Rationale: Activated receptors can autophosphorylate or activate G proteins to propagate signals.
8. Different cell types can respond differently to the same signaling molecule because:
A) The signal molecule is different in each cell
B) Each cell type converts the signal to a different metabolite
C) Receptors are identical in all cells
D) Cells do not respond to signals
Answer: B
Rationale: Different cells have different signal transduction pathways and target proteins.
9. When a lipid-soluble hormone enters a cell and binds a receptor, what happens to the receptor?
A) It is degraded immediately
B) It enters the nucleus and activates genes
C) It remains in the cytoplasm
, D) It is exported from the cell
Answer: B
Rationale: The hormone-receptor complex translocates to the nucleus and acts as a transcription factor.
10. Signaling pathways always work in complete isolation from one another.
A) True
B) False
Answer: B
Rationale: Signaling pathways cross-talk and integrate signals from multiple sources.
11. In eukaryotic cells, chromosomes are composed of:
A) RNA and lipids
B) DNA and proteins
C) Only DNA
D) Only proteins
Answer: B
Rationale: Chromosomes consist of DNA wrapped around histone proteins.
12. Forms of the Ras protein found in tumors would cause which of the following?
A) Cell cycle arrest
B) DNA replication to be hyperactive
C) Apoptosis
D) DNA repair
Answer: B
Rationale: Mutated Ras is constitutively active, driving uncontrolled cell proliferation.
13. The mitotic spindle is a microtubular structure that is involved in:
