BSC 1010 Final Exam Review 2027 | 150+ Practice
Questions & Correct Answers | Detailed Rationales |
Complete Biology Study Guide & Exam Prep
1. Put the steps of signal transduction in the correct order:
1. Conformational change activates an enzyme
2. Protein kinases are activated
3. Signal molecule binds to a receptor
4. Target proteins are phosphorylated
Second messenger molecules are released
A) 1, 3, 5, 2, 4
B) 3, 1, 5, 2, 4
C) 3, 5, 1, 2, 4
D) 5, 3, 1, 2, 4
Answer: B
Rationale: Signal binding → receptor conformational change → second messenger release → kinase
activation → target protein phosphorylation.
2. Integrins are integral membrane proteins often attached to:
A) Ribosomes and Golgi
B) Cytoskeletal proteins and extracellular matrix proteins
C) Nuclear envelope proteins
D) Mitochondrial membranes
Answer: B
Rationale: Integrins link the extracellular matrix to the cytoskeleton, providing structural support and
signaling.
,3. Phosphorylation cascades involving protein kinases amplify signals because:
A) They destroy the signal
B) Each kinase can activate many target proteins, amplifying the original signal
C) They block receptor activity
D) They reduce the number of second messengers
Answer: B
Rationale: Sequential kinase activation multiplies the signal at each step, producing a large cellular
response.
4. Steroid hormone receptors are intracellular because:
A) Steroids cannot cross the membrane
B) Steroid hormones are lipid soluble and can diffuse through the plasma membrane
C) Steroids bind to DNA directly
D) Steroids are too large to bind surface receptors
Answer: B
Rationale: Lipid-soluble steroids cross the membrane and bind intracellular receptors, which then act as
transcription factors.
5. How does the molecular composition of a plant cell wall compare with the extracellular matrix
(ECM) 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) Both consist primarily of lipids
D) Plant cell walls contain no carbohydrates
Answer: B
Rationale: Plant cell walls are mainly cellulose (carbohydrate); ECM is rich in collagen and other proteins.
,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 DNA and RNA
B) Catalyze receptor phosphorylation and activate G proteins
C) Digest proteins and lipids
D) Store calcium and ATP
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 has different intracellular proteins and pathways that interpret the signal differently
C) Receptors are identical in all cells
D) The signal is destroyed in some cells
Answer: B
Rationale: The same signal can activate different downstream effectors depending on the cell's protein
composition.
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 returns to the membrane
D) It activates G proteins
Answer: B
Rationale: Steroid-receptor complexes act as transcription factors, binding DNA to regulate gene
expression.
10. Signaling pathways always work in complete isolation from one another.
A) True
B) False
C) Only in prokaryotes
D) Only in plants
Answer: B
Rationale: Signaling pathways interact extensively through crosstalk, integration, and shared second
messengers.
11. In eukaryotic cells, chromosomes are composed of:
A) RNA and lipids
B) DNA and proteins (histones)
C) Proteins only
D) Carbohydrates and DNA
Answer: B
Rationale: Chromosomes consist of DNA wrapped around histone proteins to form chromatin.
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
Questions & Correct Answers | Detailed Rationales |
Complete Biology Study Guide & Exam Prep
1. Put the steps of signal transduction in the correct order:
1. Conformational change activates an enzyme
2. Protein kinases are activated
3. Signal molecule binds to a receptor
4. Target proteins are phosphorylated
Second messenger molecules are released
A) 1, 3, 5, 2, 4
B) 3, 1, 5, 2, 4
C) 3, 5, 1, 2, 4
D) 5, 3, 1, 2, 4
Answer: B
Rationale: Signal binding → receptor conformational change → second messenger release → kinase
activation → target protein phosphorylation.
2. Integrins are integral membrane proteins often attached to:
A) Ribosomes and Golgi
B) Cytoskeletal proteins and extracellular matrix proteins
C) Nuclear envelope proteins
D) Mitochondrial membranes
Answer: B
Rationale: Integrins link the extracellular matrix to the cytoskeleton, providing structural support and
signaling.
,3. Phosphorylation cascades involving protein kinases amplify signals because:
A) They destroy the signal
B) Each kinase can activate many target proteins, amplifying the original signal
C) They block receptor activity
D) They reduce the number of second messengers
Answer: B
Rationale: Sequential kinase activation multiplies the signal at each step, producing a large cellular
response.
4. Steroid hormone receptors are intracellular because:
A) Steroids cannot cross the membrane
B) Steroid hormones are lipid soluble and can diffuse through the plasma membrane
C) Steroids bind to DNA directly
D) Steroids are too large to bind surface receptors
Answer: B
Rationale: Lipid-soluble steroids cross the membrane and bind intracellular receptors, which then act as
transcription factors.
5. How does the molecular composition of a plant cell wall compare with the extracellular matrix
(ECM) 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) Both consist primarily of lipids
D) Plant cell walls contain no carbohydrates
Answer: B
Rationale: Plant cell walls are mainly cellulose (carbohydrate); ECM is rich in collagen and other proteins.
,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 DNA and RNA
B) Catalyze receptor phosphorylation and activate G proteins
C) Digest proteins and lipids
D) Store calcium and ATP
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 has different intracellular proteins and pathways that interpret the signal differently
C) Receptors are identical in all cells
D) The signal is destroyed in some cells
Answer: B
Rationale: The same signal can activate different downstream effectors depending on the cell's protein
composition.
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 returns to the membrane
D) It activates G proteins
Answer: B
Rationale: Steroid-receptor complexes act as transcription factors, binding DNA to regulate gene
expression.
10. Signaling pathways always work in complete isolation from one another.
A) True
B) False
C) Only in prokaryotes
D) Only in plants
Answer: B
Rationale: Signaling pathways interact extensively through crosstalk, integration, and shared second
messengers.
11. In eukaryotic cells, chromosomes are composed of:
A) RNA and lipids
B) DNA and proteins (histones)
C) Proteins only
D) Carbohydrates and DNA
Answer: B
Rationale: Chromosomes consist of DNA wrapped around histone proteins to form chromatin.
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
