CAMPBELL BIOLOGY 12TH EDITION TEST BANK - ALL 56 CHAPTERS – EXAM-
STYLE QUESTIONS AND ANSWERS | VERIFIED AND WELL DETAILED ANSWERS |
PLUS RATIONALES | GUARANTEED PASS | 2026/27 LATEST UPDATE | EXAM PREP |
STUDY GUIDE | PRACTICE TEST
SECTION ONE: QUESTIONS 1-50
1. A researcher is studying a newly discovered unicellular organism that thrives
in hydrothermal vents. It possesses a cell wall lacking peptidoglycan, unique
membrane lipids, and a genome that includes both histone-associated and
naked DNA regions. To which domain does this organism most likely belong?
A. Bacteria
B. Eukarya
C. Archaea
D. Protista
Correct Answer: C. Archaea
*Rationale: * Archaea are known for their ability to thrive in extreme
environments like hydrothermal vents. Their cell walls lack peptidoglycan, a
hallmark of Bacteria, and they possess unique ether-linked membrane lipids. The
presence of histone-associated DNA is a characteristic shared with Eukarya, but
the overall combination of features is specific to Archaea. Bacteria have
peptidoglycan in their cell walls, and Eukarya, which include Protista, have
membrane-bound organelles and a more complex cellular structure not
described here.
,2. Which of the following properties is most directly attributed to the
amphipathic nature of phospholipids in an aqueous environment?
A. The formation of a selectively permeable barrier.
B. The ability to form covalent bonds with carbohydrates.
C. The high fluidity of the membrane at low temperatures.
D. The presence of unsaturated fatty acid tails.
Correct Answer: A. The formation of a selectively permeable barrier.
*Rationale: * The amphipathic nature of phospholipids, possessing both
hydrophilic heads and hydrophobic tails, drives their self-assembly into a bilayer
in aqueous solutions. This bilayer forms the fundamental structure of a cell
membrane, which acts as a selectively permeable barrier. The high fluidity is
related to unsaturated fatty acids (Option D), but the primary consequence of
amphipathicity is the barrier itself. Option B and C are not direct results of this
property.
3. During a laboratory experiment, a cell is treated with a substance that
completely inhibits the function of ribosomes. Which of the following cellular
processes would be immediately and most directly affected?
A. DNA replication
B. Protein synthesis
C. ATP production
D. Lipid synthesis
Correct Answer: B. Protein synthesis
,*Rationale: * Ribosomes are the macromolecular machines responsible for
translation, the process of synthesizing proteins from mRNA. Inhibiting their
function would immediately halt protein synthesis. DNA replication (Option A)
occurs in the nucleus and does not directly involve ribosomes. ATP production
(Option C) is primarily a function of mitochondria and chloroplasts. Lipid
synthesis (Option D) is largely performed by enzymes in the endoplasmic
reticulum and cytoplasm.
4. A plant cell is placed in a solution that is hypertonic to its cytoplasm. Which
of the following will initially occur?
A. The cell will swell and burst.
B. The cell will become turgid.
C. Water will move out of the cell, causing the plasma membrane to pull away
from the cell wall.
D. Water will move into the cell at an equal rate as it moves out, maintaining cell
volume.
Correct Answer: C. Water will move out of the cell, causing the plasma
membrane to pull away from the cell wall.
*Rationale: * In a hypertonic environment, the extracellular solution has a lower
water potential than the cell's cytoplasm. As a result, water will move out of the
cell via osmosis. The plant cell wall is rigid and will not collapse, but the plasma
membrane will shrink and separate from the cell wall, a process known as
plasmolysis. Options A and D describe hypotonic and isotonic conditions,
respectively. Option B describes a turgid cell in a hypotonic environment.
, 5. A researcher discovers a new metabolic pathway. The first step of this
pathway is endergonic with a large positive ΔG. Which of the following
mechanisms is most likely used by the cell to drive this reaction forward?
A. Increasing the temperature of the cellular environment.
B. Coupling the reaction to the hydrolysis of ATP.
C. Increasing the concentration of the product.
D. Adding an enzyme that lowers the ΔG of the reaction.
Correct Answer: B. Coupling the reaction to the hydrolysis of ATP.
*Rationale: * Endergonic reactions are non-spontaneous and require an input of
free energy. Cells commonly drive these unfavorable reactions by coupling them
to the highly exergonic hydrolysis of ATP. The energy released from ATP
hydrolysis is used to phosphorylate the substrate, making the overall reaction
exergonic. An enzyme (Option D) lowers the activation energy and speeds up the
reaction but does not change the net ΔG. Increasing product concentration
(Option C) would push the equilibrium towards reactants.
6. In a mammalian cell, the electron transport chain establishes a proton
gradient across the inner mitochondrial membrane. What is the direct energy
source for ATP synthesis by ATP synthase?
A. The reduction of NADH to NAD+.
B. The flow of electrons from complex IV to oxygen.
C. The electrochemical gradient of protons flowing back into the mitochondrial
matrix.
D. The oxidation of FADH2.
STYLE QUESTIONS AND ANSWERS | VERIFIED AND WELL DETAILED ANSWERS |
PLUS RATIONALES | GUARANTEED PASS | 2026/27 LATEST UPDATE | EXAM PREP |
STUDY GUIDE | PRACTICE TEST
SECTION ONE: QUESTIONS 1-50
1. A researcher is studying a newly discovered unicellular organism that thrives
in hydrothermal vents. It possesses a cell wall lacking peptidoglycan, unique
membrane lipids, and a genome that includes both histone-associated and
naked DNA regions. To which domain does this organism most likely belong?
A. Bacteria
B. Eukarya
C. Archaea
D. Protista
Correct Answer: C. Archaea
*Rationale: * Archaea are known for their ability to thrive in extreme
environments like hydrothermal vents. Their cell walls lack peptidoglycan, a
hallmark of Bacteria, and they possess unique ether-linked membrane lipids. The
presence of histone-associated DNA is a characteristic shared with Eukarya, but
the overall combination of features is specific to Archaea. Bacteria have
peptidoglycan in their cell walls, and Eukarya, which include Protista, have
membrane-bound organelles and a more complex cellular structure not
described here.
,2. Which of the following properties is most directly attributed to the
amphipathic nature of phospholipids in an aqueous environment?
A. The formation of a selectively permeable barrier.
B. The ability to form covalent bonds with carbohydrates.
C. The high fluidity of the membrane at low temperatures.
D. The presence of unsaturated fatty acid tails.
Correct Answer: A. The formation of a selectively permeable barrier.
*Rationale: * The amphipathic nature of phospholipids, possessing both
hydrophilic heads and hydrophobic tails, drives their self-assembly into a bilayer
in aqueous solutions. This bilayer forms the fundamental structure of a cell
membrane, which acts as a selectively permeable barrier. The high fluidity is
related to unsaturated fatty acids (Option D), but the primary consequence of
amphipathicity is the barrier itself. Option B and C are not direct results of this
property.
3. During a laboratory experiment, a cell is treated with a substance that
completely inhibits the function of ribosomes. Which of the following cellular
processes would be immediately and most directly affected?
A. DNA replication
B. Protein synthesis
C. ATP production
D. Lipid synthesis
Correct Answer: B. Protein synthesis
,*Rationale: * Ribosomes are the macromolecular machines responsible for
translation, the process of synthesizing proteins from mRNA. Inhibiting their
function would immediately halt protein synthesis. DNA replication (Option A)
occurs in the nucleus and does not directly involve ribosomes. ATP production
(Option C) is primarily a function of mitochondria and chloroplasts. Lipid
synthesis (Option D) is largely performed by enzymes in the endoplasmic
reticulum and cytoplasm.
4. A plant cell is placed in a solution that is hypertonic to its cytoplasm. Which
of the following will initially occur?
A. The cell will swell and burst.
B. The cell will become turgid.
C. Water will move out of the cell, causing the plasma membrane to pull away
from the cell wall.
D. Water will move into the cell at an equal rate as it moves out, maintaining cell
volume.
Correct Answer: C. Water will move out of the cell, causing the plasma
membrane to pull away from the cell wall.
*Rationale: * In a hypertonic environment, the extracellular solution has a lower
water potential than the cell's cytoplasm. As a result, water will move out of the
cell via osmosis. The plant cell wall is rigid and will not collapse, but the plasma
membrane will shrink and separate from the cell wall, a process known as
plasmolysis. Options A and D describe hypotonic and isotonic conditions,
respectively. Option B describes a turgid cell in a hypotonic environment.
, 5. A researcher discovers a new metabolic pathway. The first step of this
pathway is endergonic with a large positive ΔG. Which of the following
mechanisms is most likely used by the cell to drive this reaction forward?
A. Increasing the temperature of the cellular environment.
B. Coupling the reaction to the hydrolysis of ATP.
C. Increasing the concentration of the product.
D. Adding an enzyme that lowers the ΔG of the reaction.
Correct Answer: B. Coupling the reaction to the hydrolysis of ATP.
*Rationale: * Endergonic reactions are non-spontaneous and require an input of
free energy. Cells commonly drive these unfavorable reactions by coupling them
to the highly exergonic hydrolysis of ATP. The energy released from ATP
hydrolysis is used to phosphorylate the substrate, making the overall reaction
exergonic. An enzyme (Option D) lowers the activation energy and speeds up the
reaction but does not change the net ΔG. Increasing product concentration
(Option C) would push the equilibrium towards reactants.
6. In a mammalian cell, the electron transport chain establishes a proton
gradient across the inner mitochondrial membrane. What is the direct energy
source for ATP synthesis by ATP synthase?
A. The reduction of NADH to NAD+.
B. The flow of electrons from complex IV to oxygen.
C. The electrochemical gradient of protons flowing back into the mitochondrial
matrix.
D. The oxidation of FADH2.
