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1. Some regions of the plasma membrane, called lipid rafts, have a higher concentration of
cholesterol molecules. As a result, these lipid rafts
A) are more fluid than the surrounding membrane.
B) are more rigid than the surrounding membrane.
C) are able to flip from inside to outside.
D) detach from the plasma membrane and clog arteries.
E) have higher rates of lateral diffusion of lipids and proteins into and out of the lipid
rafts.
2. Which of the following types of molecules are the major structural components of the
cell membrane?
A) phospholipids and cellulose
B) nucleic acids and proteins
C) phospholipids and proteins
D) proteins and cellulose
E) glycoproteins and cholesterol
3. Singer and Nicolson's fluid mosaic model of the membrane proposed that
A) membranes are a phospholipid bilayer.
B) membranes are a phospholipid bilayer between two layers of hydrophilic proteins.
C) membranes are a single layer of phospholipids and proteins.
D) membranes consist of protein molecules embedded in a fluid bilayer of
phospholipids.
E) membranes consist of a mosaic of polysaccharides and proteins.
4. The presence of cholesterol in the plasma membranes of some animals
A) enables the membrane to stay fluid more easily when cell temperature drops.
B) enables the animal to remove hydrogen atoms from saturated phospholipids.
C) enables the animal to add hydrogen atoms to unsaturated phospholipids.
D) makes the membrane less flexible, allowing it to sustain greater pressure from within
the cell.
E) makes the animal more susceptible to circulatory disorders.
5. In order for a protein to be an integral membrane protein it would have to be
A) hydrophilic.
B) hydrophobic.
C) amphipathic, with at least one hydrophobic region.
D) completely covered with phospholipids.
E) exposed on only one surface of the membrane.
6. Which of the following is a reasonable explanation for why unsaturated fatty acids help
keep any membrane more fluid at lower temperatures?
A) The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from
packing tightly.
B) Unsaturated fatty acids have a higher cholesterol content and therefore more
cholesterol in membranes.
C) Unsaturated fatty acids are more polar than saturated fatty acids.
D) The double bonds block interaction among the hydrophilic head groups of the lipids.
E) The double bonds result in shorter fatty acid tails and thinner membranes.
7. Which of the following is true of integral membrane proteins?
A) They lack tertiary structure.
B) They are loosely bound to the surface of the bilayer.
C) They are usually transmembrane proteins.
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D) They are not mobile within the bilayer.
E) They serve only a structural role in membranes.
Which of these are not embedded in the hydrophobic portion of the lipid bilayer at all?
A) transmembrane proteins
B) integral proteins
C) peripheral proteins
D) integrins
E) glycoproteins
What kinds of molecules pass through a cell membrane most easily?
A) large and hydrophobic
B) small and hydrophobic
C) large polar
D) ionic
E) monosaccharides such as glucose
Which of the following is a characteristic feature of a carrier protein in a plasma
membrane?
A) It is a peripheral membrane protein.
B) It exhibits a specificity for a particular type of molecule.
C) It requires the expenditure of cellular energy to function.
D) It works against diffusion.
E) It has few, if any, hydrophobic amino acids.
Nitrous oxide gas molecules passing across a cell's plasma membrane without help from
another protein and moving from high concentration to low concentration is an
example of
A) diffusion across the lipid bilayer.
B) facilitated diffusion.
C) active transport.
D) osmosis.
E) cotransport.
Which of the following would likely move through the lipid bilayer of a plasma
membrane most rapidly?
A) CO2
B) an amino acid
C) glucose
D) K⁺
E) starch
Which of the following statements is correct about diffusion?
A) It is very rapid over long distances.
B) It requires an expenditure of energy by the cell.
C) It is a passive process in which molecules move from a region of higher concentration
to a region of lower concentration.
D) It is an active process in which molecules move from a region of lower concentration
to one of higher concentration.
E) It requires integral proteins in the cell membrane.
Celery stalks that are immersed in fresh water for several hours become stiff and hard.
Similar stalks left in a 0.15 M salt solution become limp and soft. From this we can
deduce that the cells of the celery stalks are
A) hypotonic to both fresh water and the salt solution.
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B) hypertonic to both fresh water and the salt solution.
C) hypertonic to fresh water but hypotonic to the salt solution.
D) hypotonic to fresh water but hypertonic to the salt solution.
E) isotonic with fresh water but hypotonic to the salt solution.
Mammalian blood contains the equivalent of 0.15 M NaCl. Seawater contains the
equivalent of 0.45 M NaCl. What will happen if red blood cells are transferred to
seawater?
A) Water will leave the cells, causing them to shrivel and collapse.
B) NaCl will be exported from the red blood cells by facilitated diffusion.
C) The blood cells will take up water, swell, and eventually burst.
D) NaCl will passively diffuse into the red blood cells.
E) The blood cells will expend ATP for active transport of NaCl into the cytoplasm.
Which of the following statements correctly describes the normal tonicity conditions for
typical plant and animal cells?
A) The animal cell is in a hypotonic solution, and the plant cell is in an isotonic solution.
B) The animal cell is in an isotonic solution, and the plant cell is in a hypertonic solution.
C) The animal cell is in a hypertonic solution, and the plant cell is in an isotonic solution.
D) The animal cell is in an isotonic solution, and the plant cell is in a hypotonic solution.
E) The animal cell is in a hypertonic solution, and the plant cell is in a hypotonic solution.
When a plant cell, such as one from a peony stem, is submerged in a very hypotonic
solution, what is likely to occur?
A) The cell will burst.
B) The cell membrane will lyse.
C) Plasmolysis will shrink the interior.
D) The cell will become flaccid.
E) The cell will become turgid.
The phosphate transport system in bacteria imports phosphate into the cell even when
the concentration of phosphate outside the cell is much lower than the cytoplasmic
phosphate concentration. Phosphate import depends on a pH gradient across the
membrane–more acidic outside the cell than inside the cell. Phosphate transport is an
example of
A) passive diffusion.
B) facilitated diffusion.
C) active transport.
D) osmosis.
E) cotransport.
Glucose diffuses slowly through artificial phospholipid bilayers. The cells lining the small
intestine, however, rapidly move large quantities of glucose from the glucose-rich food
into their glucose-poor cytoplasm. Using this information, which transport mechanism is
most probably functioning in the intestinal cells?
A) simple diffusion
B) phagocytosis
C) active transport pumps
D) exocytosis
E) facilitated diffusion
An organism with a cell wall would most likely be unable to take in materials through
A) diffusion.
B) osmosis.
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C) active transport.
D) phagocytosis.
E) facilitated diffusion.
A bacterium engulfed by a white blood cell through phagocytosis will be digested by
enzymes contained in
A) peroxisomes.
B) lysosomes.
C) Golgi vesicles.
D) vacuoles.
E) secretory vesicles.
According to the fluid mosaic model of membrane structure, proteins of the membrane
are mostly
A) spread in a continuous layer over the inner and outer surfaces of the membrane.
B) confined to the hydrophobic interior of the membrane.
C) embedded in a lipid bilayer.
D) randomly oriented in the membrane, with no fixed inside-outside polarity.
E) free to depart from the fluid membrane and dissolve in the surrounding solution.
Which of the following factors would tend to increase membrane fluidity?
A) a greater proportion of unsaturated phospholipids
B) a greater proportion of saturated phospholipids
C) a lower temperature
D) a relatively high protein content in the membrane
E) a greater proportion of relatively large glycolipids compared with lipids having smaller
molecular masses
When biologists wish to study the internal ultrastructure of cells, they can achieve the
finest resolution by using
A) a phase-contrast light microscope.
B) a scanning electron microscope.
C) a transmission electronic microscope.
D) a confocal fluorescence microscope.
E) a super-resolution fluorescence microscope.
The advantage of light microscopy over electron microscopy is that
A) light microscopy provides for higher magnification than electron microscopy.
B) light microscopy provides for higher resolving power than electron microscopy.
C) light microscopy allows one to view dynamic processes in living cells.
D) light microscopy provides higher contrast than electron microscopy.
E) specimen preparation for light microcopy does not produce artifacts.
All of the following are part of a prokaryotic cell except
A) DNA.
B) a cell wall.
C) a plasma membrane.
D) ribosomes.
E) an endoplasmic reticulum.
The volume enclosed by the plasma membrane of plant cells is often much larger than
the corresponding volume in animal cells. The most reasonable explanation for this
observation is that
A) plant cells are capable of having a much higher surface-to-volume ratio than animal
cells.
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B) plant cells have a much more highly convoluted (folded) plasma membrane than
animal cells.
C) plant cells contain a large vacuole that reduces the volume of the cytoplasm.
D) animal cells are more spherical, whereas plant cells are elongated.
E) plant cells can have lower surface-to-volume ratios than animal cells because plant
cells synthesize their own nutrients.
The evolution of eukaryotic cells most likely involved
A) endosymbiosis of an aerobic bacterium in a larger host cell–the endosymbiont
evolved into mitochondria.
B) anaerobic archaea taking up residence inside a larger bacterial host cell to escape
toxic oxygen–the anaerobic bacterium evolved into chloroplasts.
C) an endosymbiotic fungal cell evolved into the nucleus.
D) acquisition of an endomembrane system, and subsequent evolution of mitochondria
from a portion of the Golgi.
Which organelle or structure is absent in plant cells?
A) mitochondria
B) Golgi vesicles
C) microtubules
D) centrosomes
E) peroxisomes
Large numbers of ribosomes are present in cells that specialize in producing which of
the following molecules?
A) lipids
B) glycogen
C) proteins
D) cellulose
E) nucleic acids
Which type of organelle or structure is primarily involved in the synthesis of oils,
phospholipids, and steroids?
A) ribosome
B) lysosome
C) smooth endoplasmic reticulum
D) mitochondrion
E) contractile vacuole
Which structure is the site of the synthesis of proteins that may be exported from the
cell?
A) rough ER
B) lysosomes
C) plasmodesmata
D) Golgi vesicles
E) free cytoplasmic ribosomes
The Golgi apparatus has a polarity or sidedness to its structure and function. Which of
the following statements correctly describes this polarity?
A) Transport vesicles fuse with one side of the Golgi and leave from the opposite side.
B) Proteins in the membrane of the Golgi may be sorted and modified as they move
from one side of the Golgi to the other.
C) Lipids in the membrane of the Golgi may be sorted and modified as they move from
one side of the Golgi to the other.
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D) Soluble proteins in the cisternae (interior) of the Golgi may be sorted and modified as
they move from one side of the Golgi to the other.
E) All of the above correctly describe polar characteristics of the Golgi function.
Hydrolytic enzymes must be segregated and packaged to prevent general destruction of
cellular components. Which of the following organelles contains these hydrolytic
enzymes in animal cells?
A) chloroplast
B) lysosome
C) central vacuole
D) peroxisome
E) glyoxysome
The liver is involved in detoxification of many poisons and drugs. Which of the following
structures is primarily involved in this process and therefore abundant in liver cells?
A) rough ER
B) smooth ER
C) Golgi apparatus
D) nuclear envelope
E) transport vesicles
Which of the following produces and modifies polysaccharides that will be secreted?
A) lysosome
B) vacuole
C) mitochondrion
D) Golgi apparatus
E) peroxisome
Which organelle often takes up much of the volume of a plant cell?
A) lysosome
B) vacuole
C) mitochondrion
D) Golgi apparatus
E) peroxisome
Which organelle is the primary site of ATP synthesis in eukaryotic cells?
A) lysosome
B) vacuole
C) mitochondrion
D) Golgi apparatus
E) peroxisome
Which plant cell organelle contains its own DNA and ribosomes?
A) glyoxysome
B) vacuole
C) mitochondrion
D) Golgi apparatus
E) peroxisome
Thylakoids, DNA, and ribosomes are all components found in
A) vacuoles.
B) chloroplasts.
C) mitochondria.
D) lysosomes.
E) nuclei.
41. In a plant cell, DNA may be found
A) only in the nucleus.
B) only in the nucleus and mitochondria.
C) only in the nucleus and chloroplasts.
D) in the nucleus, mitochondria, and chloroplasts.
E) in the nucleus, mitochondria, chloroplasts, and peroxisomes.
42. Motor proteins provide for molecular motion in cells by interacting with what types of
cellular structures?
A) sites of energy production in cellular respiration
B) membrane proteins
C) ribosomes
D) cytoskeletal structures
E) cellulose fibers in the cell wall
43. Movement of vesicles within the cell depends on what cellular structures?
A) microtubules and motor proteins
B) actin filaments and microtubules
C) actin filaments and ribosomes
D) centrioles and motor proteins
E) actin filaments and motor proteins
44. Which of the following contain the 9 + 2 arrangement of microtubules, consisting of
nine doublets of microtubules surrounding a pair of single microtubules?
A) both motile cilia and primary (nonmotile) cilia
B) centrioles only
C) both flagella and motile cilia
D) both basal bodies and primary (nonmotile) cilia
E) both centrioles and basal bodies
45. What do the cell walls of plants and the extracellular matrix of animal cells have in
common?
A) They are largely composed of phospholipids and glycoproteins.
B) Their proteins are made by free cytoplasmic ribosomes.
C) They form rigid structures that provide structural support for cells but limit their
expansion.
D) They limit the passage of small molecules.
E) They have functional connections with the cytoskeleton inside the cell.
46. Which of the following is present in a prokaryotic cell?
A) mitochondrion
B) ribosome
C) nuclear envelope
D) chloroplast
E) ER
47. Which structure-function pair is mismatched?
A) nucleolus; production of ribosomal subunits
B) lysosome; intracellular digestion
C) ribosome; protein synthesis
D) Golgi; protein trafficking
E) microtubule; muscle contraction
48. Which of the following is (are) true for anabolic pathways?
A) They do not depend on enzymes.
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B) They are usually highly spontaneous chemical reactions.
C) They consume energy to build up polymers from monomers.
D) They release energy as they degrade polymers to monomers.
E) They consume energy to decrease the entropy of the organism and its environment.
Which of the following is a statement of the first law of thermodynamics?
A) Energy cannot be created or destroyed.
B) The entropy of the universe is decreasing.
C) The entropy of the universe is constant.
D) Kinetic energy is stored energy that results from the specific arrangement of matter.
E) Energy cannot be transferred or transformed.
Living organisms increase in complexity as they grow, resulting in a decrease in the
entropy of an organism. How does this relate to the second law of thermodynamics?
A) Living organisms do not obey the second law of thermodynamics, which states that
entropy must increase with time.
B) Life obeys the second law of thermodynamics because the decrease in entropy as the
organism grows is exactly balanced by an increase in the entropy of the universe.
C) Living organisms do not follow the laws of thermodynamics.
D) As a consequence of growing, organisms cause a greater increase in entropy in their
environment than the decrease in entropy associated with their growth.
E) Living organisms are able to transform energy into entropy.
Whenever energy is transformed, there is always an increase in the
A) free energy of the system.
B) free energy of the universe.
C) entropy of the system.
D) entropy of the universe.
E) enthalpy of the universe.
In alcohol fermentation, NAD⁺ is regenerated from NADH by
A) reduction of acetaldehyde to ethanol (ethyl alcohol).
B) oxidation of pyruvate to acetyl CoA.
C) reduction of pyruvate to form lactate.
D) oxidation of ethanol to acetyl CoA.
E) reduction of ethanol to pyruvate.
Which of the following is an example of potential rather than kinetic energy?
A) the muscle contractions of a person mowing grass
B) water rushing over Niagara Falls
C) light flashes emitted by a firefly
D) a molecule of glucose
E) the flight of an insect foraging for food
Which of the following is true of metabolism in its entirety in all organisms?
A) Metabolism depends on a constant supply of energy from food.
B) Metabolism depends on an organism's adequate hydration.
C) Metabolism uses all of an organism's resources.
D) Metabolism consists of all the energy transformation reactions in an organism.
E) Metabolism manages the increase of entropy in an organism.
The mathematical expression for the change in free energy of a system is ΔG =ΔH - TΔS.
Which of the following is (are) correct?
A) ΔS is the change in enthalpy, a measure of randomness.
B) ΔH is the change in entropy, the energy available to do work.
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C) ΔG is the change in free energy.
D) T is the temperature in degrees Celsius.
Which of the following is true for all exergonic reactions?
A) The products have more total energy than the reactants.
B) The reaction proceeds with a net release of free energy.
C) The reaction goes only in a forward direction: all reactants will be converted to
products, but no products will be converted to reactants.
D) A net input of energy from the surroundings is required for the reactions to proceed.
E) The reactions are rapid.
A chemical reaction that has a positive ΔG is correctly described as
A) endergonic.
B) endothermic.
C) enthalpic.
D) spontaneous.
E) exothermic.
Which of the following best describes enthalpy (H)?
A) the total kinetic energy of a system
B) the heat content of a chemical system
C) the system's entropy
D) the cell's energy equilibrium
E) the condition of a cell that is not able to react
Why is ATP an important molecule in metabolism?
A) Its hydrolysis provides an input of free energy for exergonic reactions.
B) It provides energy coupling between exergonic and endergonic reactions.
C) Its terminal phosphate group contains a strong covalent bond that, when hydrolyzed,
releases free energy.
D) Its terminal phosphate bond has higher energy than the other two.
E) It is one of the four building blocks for DNA synthesis.
Which of the following statements is true concerning catabolic pathways?
A) They combine molecules into more energy-rich molecules.
B) They supply energy, primarily in the form of ATP, for the cell's work.
C) They are endergonic.
D) They are spontaneous and do not need enzyme catalysis.
E) They build up complex molecules such as protein from simpler compounds.
When chemical, transport, or mechanical work is done by an organism, what happens to
the heat generated?
A) It is used to power yet more cellular work.
B) It is used to store energy as more ATP.
C) It is used to generate ADP from nucleotide precursors.
D) It is lost to the environment.
E) It is transported to specific organs such as the brain.
Reactants capable of interacting to form products in a chemical reaction must first
overcome a thermodynamic barrier known as the reaction's
A) entropy.
B) activation energy.
C) endothermic level.
D) equilibrium point.
E) free-energy content.
63. Which of the following statements regarding enzymes is true?
A) Enzymes increase the rate of a reaction by making the reaction more exergonic.
B) Enzymes increase the rate of a reaction by lowering the activation energy barrier.
C) Enzymes increase the rate of a reaction by reducing the rate of reverse reactions.
D) Enzymes change the equilibrium point of the reactions they catalyze.
E) Enzymes make the rate of a reaction independent of substrate concentrations.
64. During a laboratory experiment, you discover that an enzyme-catalyzed reaction has a
∆G of -20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the
∆G for the new reaction?
A) -40 kcal/mol
B) -20 kcal/mol
C) 0 kcal/mol
D) +20 kcal/mol
E) +40 kcal/mol
65. According to the induced fit hypothesis of enzyme catalysis, which of the following is
correct?
A) The binding of the substrate depends on the shape of the active site.
B) Some enzymes change their structure when activators bind to the enzyme.
C) A competitive inhibitor can outcompete the substrate for the active site.
D) The binding of the substrate changes the shape of the enzyme's active site.
E) The active site creates a microenvironment ideal for the reaction
66. The mechanism in which the end product of a metabolic pathway inhibits an earlier step
in the pathway is most precisely described as
A) metabolic inhibition.
B) feedback inhibition.
C) allosteric inhibition.
D) noncooperative inhibition.
E) reversible inhibition.
67. Choose the pair of terms that correctly completes this sentence: Catabolism is to
anabolism as ________ is to ________.
A) exergonic; spontaneous
B) exergonic; endergonic
C) free energy; entropy
D) work; energy
E) entropy; enthalpy
68. If an enzyme is added to a solution where its substrate and product are in equilibrium,
what will occur?
A) Additional product will be formed.
B) Additional substrate will be formed.
C) The reaction will change from endergonic to exergonic.
D) The free energy of the system will change.
E) Nothing; the reaction will stay at equilibrium.
69. What is the term for metabolic pathways that release stored energy by breaking down
complex molecules?
A) anabolic pathways
B) catabolic pathways
C) fermentation pathways
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D) thermodynamic pathways
E) bioenergetic pathways
The molecule that functions as the reducing agent (electron donor) in a redox or
oxidation-reduction reaction
A) gains electrons and gains potential energy.
B) loses electrons and loses potential energy.
C) gains electrons and loses potential energy.
D) loses electrons and gains potential energy.
E) neither gains nor loses electrons, but gains or loses potential energy.
Which of the following statements describes the results of this reaction?
C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O + Energy
A) C₆H₁₂O₆ is oxidized and O₂ is reduced.
B) O₂ is oxidized and H₂O is reduced.
C) CO₂ is reduced and O₂ is oxidized.
D) C₆H₁₂O₆ is reduced and CO₂ is oxidized.
E) O₂ is reduced and CO₂ is oxidized.
When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction
reaction, the molecule becomes
A) hydrolyzed.
B) hydrogenated.
C) oxidized.
D) reduced.
E) an oxidizing agent.
When a molecule of NAD⁺ (nicotinamide adenine dinucleotide) gains a hydrogen atom
(not a proton), the molecule becomes
A) dehydrogenated.
B) oxidized.
C) reduced.
D) redoxed.
E) hydrolyzed.
Where does glycolysis take place in eukaryotic cells?
A) mitochondrial matrix
B) mitochondrial outer membrane
C) mitochondrial inner membrane
D) mitochondrial intermembrane space
E) cytosol
The ATP made during glycolysis is generated by
A) substrate-level phosphorylation.
B) electron transport.
C) photophosphorylation.
D) chemiosmosis.
E) oxidation of NADH to NAD⁺.
Which of the following statements describes NAD⁺?
A) NAD⁺ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid
cycle.
B) NAD⁺ has more chemical energy than NADH.
C) NAD⁺ is oxidized by the action of hydrogenases.
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D) NAD⁺ can donate electrons for use in oxidative phosphorylation.
E) In the absence of NAD⁺, glycolysis can still function.
Which process in eukaryotic cells will proceed normally whether oxygen (O₂) is present
or absent?
A) electron transport
B) glycolysis
C) the citric acid cycle
D) oxidative phosphorylation
E) chemiosmosis
In addition to ATP, what are the end products of glycolysis?
A) CO₂ and H₂O
B) CO₂ and pyruvate
C) NADH and pyruvate
D) CO₂ and NADH
E) H₂O, FADH₂, and citrate
In glycolysis, for each molecule of glucose oxidized to pyruvate
A) two molecules of ATP are used and two molecules of ATP are produced.
B) two molecules of ATP are used and four molecules of ATP are produced.
C) four molecules of ATP are used and two molecules of ATP are produced.
D) two molecules of ATP are used and six molecules of ATP are produced.
E) six molecules of ATP are used and six molecules of ATP are produced.
Why is glycolysis described as having an investment phase and a payoff phase?
A) It both splits molecules and assembles molecules.
B) It attaches and detaches phosphate groups.
C) It uses glucose and generates pyruvate.
D) It shifts molecules from cytosol to mitochondrion.
E) It uses stored ATP and then forms a net increase in ATP.
Which of the following intermediary metabolites enters the citric acid cycle and is
formed, in part, by the removal of a carbon (CO₂) from one molecule of pyruvate?
A) lactate
B) glyceraldehydes-3-phosphate
C) oxaloacetate
D) acetyl CoA
E) citrate
During cellular respiration, acetyl CoA accumulates in which location?
A) cytosol
B) mitochondrial outer membrane
C) mitochondrial inner membrane
D) mitochondrial intermembrane space
E) mitochondrial matrix
Carbon dioxide (CO₂) is released during which of the following stages of cellular
respiration?
A) glycolysis and the oxidation of pyruvate to acetyl CoA
B) oxidation of pyruvate to acetyl CoA and the citric acid cycle
C) the citric acid cycle and oxidative phosphorylation
D) oxidative phosphorylation and fermentation
E) fermentation and glycolysis
84. Where are the proteins of the electron transport chain located?
A) cytosol
B) mitochondrial outer membrane
C) mitochondrial inner membrane
D) mitochondrial intermembrane space
E) mitochondrial matrix
85. In cellular respiration, the energy for most ATP synthesis is supplied by
A) high energy phosphate bonds in organic molecules.
B) a proton gradient across a membrane.
C) converting oxygen to ATP.
D) transferring electrons from organic molecules to pyruvate.
E) generating carbon dioxide and oxygen in the electron transport chain.
86. The primary role of oxygen in cellular respiration is to
A) yield energy in the form of ATP as it is passed down the respiratory chain.
B) act as an acceptor for electrons and hydrogen, forming water.
C) combine with carbon, forming CO₂.
D) combine with lactate, forming pyruvate.
E) catalyze the reactions of glycolysis.
87. In chemiosmotic phosphorylation, what is the most direct source of energy that is used
to convert ADP + Pi to ATP?
A) energy released as electrons flow through the electron transport system
B) energy released from substrate-level phosphorylation
C) energy released from movement of protons through ATP synthase, against the
electrochemical gradient
D) energy released from movement of protons through ATP synthase, down the
electrochemical gradient
E) No external source of energy is required because the reaction is exergonic.
88. Energy released by the electron transport chain is used to pump H⁺ into which location
in eukaryotic cells?
A) cytosol
B) mitochondrial outer membrane
C) mitochondrial inner membrane
D) mitochondrial intermembrane space
E) mitochondrial matrix
89. The direct energy source that drives ATP synthesis during respiratory oxidative
phosphorylation in eukaryotic cells is
A) oxidation of glucose to CO₂ and water.
B) the thermodynamically favorable flow of electrons from NADH to the mitochondrial
electron transport carriers.
C) the final transfer of electrons to oxygen.
D) the proton-motive force across the inner mitochondrial membrane.
E) the thermodynamically favorable transfer of phosphate from glycolysis and the citric
acid cycle intermediate molecules of ADP.
90. When hydrogen ions are pumped from the mitochondrial matrix across the inner
membrane and into the intermembrane space, the result is the
A) formation of ATP.
B) reduction of NAD⁺.
C) restoration of the Na⁺/K⁺ balance across the membrane.
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D) creation of a proton-motive force.
E) lowering of pH in the mitochondrial matrix.
Where is ATP synthase located in the mitochondrion?
A) cytosol
B) electron transport chain
C) outer membrane
D) inner membrane
E) mitochondrial matrix
Approximately how many molecules of ATP are produced from the complete oxidation
of two molecules of glucose (C₆H₁₂O₆) in aerobic cellular respiration?
A) 2
B) 4
C) 15
D) 30-32
E) 60-64
Chemiosmotic ATP synthesis (oxidative phosphorylation) occurs in
A) all cells, but only in the presence of oxygen.
B) only eukaryotic cells, in the presence of oxygen.
C) only in mitochondria, using either oxygen or other electron acceptors.
D) all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other
electron acceptors.
E) all cells, in the absence of respiration.
In liver cells, the inner mitochondrial membranes are about five times the area of the
outer mitochondrial membranes. What purpose must this serve?
A) It allows for an increased rate of glycolysis.
B) It allows for an increased rate of the citric acid cycle.
C) It increases the surface for oxidative phosphorylation.
D) It increases the surface for substrate-level phosphorylation.
E) It allows the liver cell to have fewer mitochondria.
In a mitochondrion, if the matrix ATP concentration is high, and the intermembrane
space proton concentration is too low to generate sufficient proton-motive force, then
A) ATP synthase will increase the rate of ATP synthesis.
B) ATP synthase will stop working.
C) ATP synthase will hydrolyze ATP and pump protons into the intermembrane space.
D) ATP synthase will hydrolyze ATP and pump protons into the matrix.
E) None of the above
Which of the following normally occurs regardless of whether or not oxygen (O₂) is
present?
A) glycolysis
B) fermentation
C) oxidation of pyruvate to acetyl CoA
D) citric acid cycle
E) oxidative phosphorylation (chemiosmosis)
In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the
production of
A) ATP, CO₂, and ethanol (ethyl alcohol).
B) ATP, CO₂, and lactate.
C) ATP, NADH, and pyruvate.
D) ATP, pyruvate, and oxygen.
E) ATP, pyruvate, and acetyl CoA.
98. One function of both alcohol fermentation and lactic acid fermentation is to
A) reduce NAD⁺ to NADH.
B) reduce FAD⁺ to FADH₂.
C) oxidize NADH to NAD⁺.
D) reduce FADH₂ to FAD⁺.
E) do none of the above.
99. The final electron acceptor of the electron transport chain that functions in aerobic
oxidative phosphorylation is
A) oxygen.
B) water.
C) NAD⁺.
D) pyruvate.
E) ADP.