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1) Which of the following types of molecules are the
major structural components of the cell membrane?
A) nucleic acids and proteins B) phospholipids and proteins C) phospholipids and cellulose
D) proteins and cellulose E) glycoproteins and cholesterol
2) 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 result in shorter fatty acid
tails and thinner membranes.
B) The double bonds form kinks in the fatty acid
tails, preventing adjacent lipids from packing tightly.
C) Unsaturated fatty acids have a higher cholesterol
content and therefore more cholesterol in membranes.
D) The double bonds block interaction among the
hydrophilic head groups of the lipids.
3) The primary function of polysaccharides attached
to the glycoproteins and glycolipids of animal cell membranes is
A) to maintain membrane fluidity at low
temperatures. B) to mediate
cell-to-cell recognition.
C) to actively transport molecules against their
concentration gradients.
D) to facilitate diffusion of molecules down their
concentration gradients.
4) Which of these are never embedded in the
hydrophobic portion of the lipid bilayer at all?
A) transmembrane proteins B) glycoproteins C)
integrins
5) Why are lipids and proteins free to move
laterally in membranes?
A) Lipids and proteins repulse each other in the
membrane.
B) Molecules such as cellulose can pull them in
various directions.
C) There are only weak hydrophobic interactions in
the interior of the membrane.
D) Hydrophilic portions of the lipids are in the
interior of the membrane.
6) What kinds of molecules pass through a cell
membrane most easily?
A) ionic B)
large and hydrophobic C)
monosaccharides such as glucose
7) Which of the following statements correctly
describes the normal tonicity conditions for typical plant and animal cells?
A) The animal cell is in an isotonic solution, and
the plant cell is in a hypertonic solution.
B) The animal cell is in an isotonic solution, and
the plant cell is in a hypotonic solution.
C) The animal cell is in a hypotonic solution, and
the plant cell is in an isotonic solution.
D) The animal cell is in a hypertonic 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 an isotonic solution.
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8) White blood cells engulf bacteria through what
process?
A) phagocytosis
B) pinocytosis C) osmosis D)
exocytosis E) receptor-mediated exocytosis
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9) Ions diffuse across membranes through specific
ion channels
A) down their chemical gradients. B) down the osmotic potential gradients.
C) down the electrical gradients. D) down their electrochemical
gradients.
10) The difference between pinocytosis and
receptor-mediated endocytosis is that
A) pinocytosis can concentrate substances from the
extracellular fluid, but receptor-mediated endocytosis cannot.
B) pinocytosis is nonselective in the molecules it
brings into the cell, whereas receptor-mediated endocytosis offers more
selectivity.
C) pinocytosis increases the surface area of the
plasma membrane whereas receptor-mediated endocytosis decreases the plasma
membrane surface area.
D) pinocytosis requires cellular energy, but
receptor-mediated endocytosis does not.
E) pinocytosis brings only water molecules into the
cell, but receptor-mediated endocytosis brings in other molecules as well.
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11) You are working on a team that is designing a
new drug. In order for this drug to work, it must enter the cytoplasm of
specific target cells. Which of the following would be a factor that determines
whether the molecule selectively enters the target cells?
A) hydrophobicity of the drug molecule B) blood or tissue type of the patient
C) lack of charge on the drug molecule D) lipid composition of the target
cells' plasma membrane
E) similarity of the drug molecule to other
molecules transported by the target cells
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12) Which of the following factors would tend to
increase membrane fluidity?
A) a lower temperature
B) a greater proportion of relatively large glycolipids
compared with lipids having smaller molecular masses
C) a greater proportion of saturated phospholipids
D) a greater proportion of unsaturated phospholipids
13) ______ are the major lipids of plasma membranes.
14) ______ code for the structure of proteins.
15) 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) free to depart from the fluid membrane and
dissolve in the surrounding solution.
C) randomly oriented in the membrane, with no fixed
inside-outside polarity.
D) confined to the hydrophobic interior of the
membrane.
16) If a red blood cell is placed in a salt solution
and bursts, what is the tonicity of the solution relative to the interior of
the cell?
A) isotonic B)
hypertonic C) hypotonic D) osmotic
17) The permeability of a biological membrane to a
specific polar solute may depend on which of the following?
A) the amount of cholesterol in the membrane
B) the types of transport proteins in the membrane
C) the phospholipid composition of the membrane
D) the presence of unsaturated fatty acids in the
membrane
18) Which of the following statements about osmosis
is correct?
A) Osmosis is the diffusion of water from a region
of lower water concentration to a region of higher water concentration
B) If a solution outside the cell is hypertonic
compared to the cytoplasm, water will move into the cell by osmosis
C) The presence of aquaporins (proteins that form
water channels in the membrane) should speed up the process of osmosis
D) Osmotic movement of water out of a cell would
likely occur if the cell accumulates water from its environment.
E) If a cell is placed in an isotonic solution, more
water will enter the cell than leave the cell.
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19) In facilitated diffusion, what is the role of
the transport protein?
A) Transport proteins provide the energy for
diffusion of the solute.
B) Transport proteins organize the phospholipids to
allow the solute to cross the membrane.
C) Transport proteins provide a hydrophilic route
for the solute to cross the membrane.
D) Transport proteins provide a low-resistance
channel for water molecules to cross the membrane.
E) Transport proteins provide a protein site for ATP
hydrolysis, which facilitates the movement of a solute across a membrane.
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20) What distinguishes facilitated diffusion from
simple diffusion?
A) Water moves through membranes by facilitated diffusion
B) No energy is used to move molecules across the
membrane
C) Molecules move from a region of higher
concentration to a region of lower concentration.
21) Which of the following statements is true about
the net movement of an ion across a membrane by passive diffusion through a
membrane channel?
A) The charge on the other side of the membrane is
generally the opposite of the ion’s charge.
B) There is a higher concentration of ions on the
side of the membrane toward which the ion diffuses.
C) The cell expends energy as the ion passes through
the membrane.
D) For every ion that diffuses through the membrane,
a different ion diffuses in the opposite direction.
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22) Active and passive transport of
solutes across a membrane typically differ in which of the following ways?
A) Active transport is ussually
down the concentration gradient of the solute, whereas passive transport is
always against the concentration gradient of the solute.
B) Active transport always involves
the ultilization of cellular energy, whereas passive transport does not require
cellular enrgy.
C) Active transport is always
faster than passive transport.
D) Active transport uses protein
carriers, wheras passive transport uses carbohydrate carriers.
E) Active transport is used for
ions, passive transport is used for uncharged solutes.
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23) A chemical reaction that has a positive ΔG is
correctly described as
24) Why is ATP an important molecule in metabolism?
A) It provides energy coupling between exergonic and
endergonic reactions.
B) Its terminal phosphate group contains a strong
covalent bond that, when hydrolyzed, releases free energy.
C) Its terminal phosphate bond has higher energy
than the other two.
D) It is one of the four building blocks for DNA
synthesis.
25) Which of the following is most similar in structure
to ATP?
A) a pentose sugar B)
a phospholipid C) an amino acid
with three phosphate groups attached
26) When chemical, transport, or mechanical work is
done by an organism, what happens to the heat generated?
A) It is transported to specific organs such as the
brain. B) It is used to store energy
as more ATP.
C) It is lost to the environment. D) It
is used to power yet more cellular work.
27) Which of the following statements is true about
enzyme-catalyzed reactions?
A) Enzyme-catalyzed reactions require energy to
activate the enzyme.
B) The reaction is faster than the same reaction in
the absence of the enzyme.
C) Enzyme-catalyzed reactions release more free
energy than noncatalyzed reactions.
D) The free energy change of the reaction is
opposite from the reaction that occurs in the absence of the enzyme.
28) Reactants capable of interacting to form
products in a chemical reaction must first overcome a thermodynamic barrier known
as the reaction's
A) endothermic level. B) entropy. C) free-energy content.
29) According to the induced fit hypothesis of
enzyme catalysis, which of the following is correct?
A) The binding of the substrate changes the shape of
the enzyme's active site.
B) The binding of the substrate depends on the shape
of the active site.
C) The active site creates a microenvironment ideal
for the reaction.
D) Some enzymes change their structure when
activators bind to the enzyme.
30) When you have a severe fever, what grave
consequence may occur if the fever is not controlled?
A) removal of the amino acids in active sites of
your enzymes B) removal of amine groups
from your proteins
C) binding of your enzymes to inappropriate
substrates D) destruction of your
enzymes' primary structure
31) The mechanism in which the end product of a
metabolic pathway inhibits an earlier step in the pathway is most precisely
described as
A) allosteric inhibition. B) reversible inhibition. C)
feedback inhibition.
32) Besides turning enzymes on or off, what other
means does a cell use to control enzymatic activity?
A) hydrophobic interactions B) connecting enzymes into large
aggregates
C) cessation of cellular protein synthesis D) exporting enzymes out of the cell
Rate of an enzyme-catalyzed reaction as a function
of varying reactant concentration, with the concentration of enzyme constant.
33) For the enzyme-catalyzed reaction shown in the
figure above, which of these treatments will cause the greatest increase in the
rate of the reaction, if the initial reactant concentration is 1.0 micromolar?
A) doubling the activation energy needed B) cooling the reaction by 10°C
C) doubling the enzyme concentration
D) increasing the concentration of reactants to 10.0
micromolar, while reducing the concentration of enzyme by 1/2
E) doubling the concentration of the reactants to
2.0 micromolar
34) In the figure above, why does the reaction rate
plateau at higher reactant concentrations?
A) The reaction nears equilibrium at high reactant
concentrations.
B) The rate of the reverse reaction increases with
reactant concentration.
C) Most enzyme molecules are occupied by substrate
at high reactant concentrations.
D) The activation energy for the reaction increases
with reactant concentration.
A series of enzymes catalyze the reaction X → Y → Z → A. Product A
binds to the enzyme that converts X to Y at a position remote from its active
site. This binding decreases the activity of the enzyme.
35) What is substance X?
A) a coenzyme B) a substrate C) an allosteric inhibitor
D) the product E) an
intermediate
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36) With respect to the enzyme that converts X to Y,
substance A functions as
A) a coenzyme. B)
an intermediate. C) an
allosteric inhibitor.
D) a competitive inhibitor. E) the substrate.
Succinate dehydrogenase catalyzes the conversion of
succinate to fumarate. The reaction is inhibited by malonic acid, which
resembles succinate but cannot be acted upon by succinate dehydrogenase.
Increasing the ratio of succinate to malonic acid reduces the inhibitory effect
of malonic acid.
37) Based on this information, which of the following
is correct?
A) Succinate dehydrogenase is the enzyme, and
malonic acid is the substrate.
B) Succinate dehydrogenase is the enzyme, and
fumarate is the substrate.
C) Succinate is the substrate, and fumarate is the
product.
D) Fumarate is the product, and malonic acid is a
noncompetitive inhibitor.
38) What is malonic acid's role with respect to succinate
dehydrogenase?
A) It blocks the binding of fumarate. B) It is a competitive inhibitor. C) It is an allosteric regulator.
39) Some bacteria are metabolically active in hot
springs because
A) their enzymes have high optimal temperatures.
B) their enzymes are completely insensitive to
temperature.
C) they use molecules other than proteins or RNAs as
their main catalysts.
D) they are able to maintain a lower internal
temperature.
40) Which of these is exhibiting kinetic energy?
A) a rock on a mountain ledge B) a space station orbiting
Earth
C) a person sitting on a couch while watching TV D) an archer with a with a flexed bow
41) Which of the following would be unlikely
to contribute to the substrate specificity of an enzyme?
A) A similar shape exists between a pocket on the
surface of the enzyme and a functional group on the substrate
B) A hydropobic group on the substrate interacts
with several hydrophobic amino acids on the enzyme
C) A positive charge on the substrate is attached to
a negative charge in the active site of the enzyme.
D) The enzyme has the ability to change its
confirmation in response to the substrate binding.
42) Which of the following is NOT a
way in which an enzyme can speed up the reaction that it catalyzes?
A) The enzyme binds a cofactor that
interacts with the substrate to facilitate the reaction.
B) Binding of the substrate to the
active site can streatch bonds in the substrate that need to be broken.
C) The active site of the enzyme
can provide a microenvironment with a different pH that facilitates the
reaction.
D) The binding of two substrates in
the active site provides the correct orientation for them to react to form the
product.
E) The active site can provide heat
from the environment that raises the energy content of the substrate.
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43) Aerobic means with ______.
44) The waste products of cellular respiration
include ______.
A) carbon dioxide B)
water C) glucose D) water and carbon dioxide E) water and glucose
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45) The binding of a compound to an
enzyme is observed to slow down or stop the rate of the reaction catalyzed by
the enzyme. Increasing the substrate concentration reduces the inhibitory
effects of this compound. Which of the following could account for this
observation?
A) The compound is a competitive
inhibitor.
B) The compound is a negative
allosteric regulator.
C) The compound causes a cofactor
to be lost from the enzyme.
D) The compound forms a bond with
one of the amino acid residues needed for enzyme activity.
E) The compound reduces disulfide
bonds, causing the enzyme molecules to partially unfold.
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46) What compound directly provides energy for
cellular work?
47) Respiration ______, and cellular respiration
______.
A) produces glucose . . . produces oxygen B) is gas exchange . . . produces ATP
C) produces ATP . . . is gas exchange D) produces glucose . . . is gas
exchange
48) Which of these equations describes aerobic
cellular respiration?
A) glucose + lactose → galactose + water B) glucose → lactic acid +
energy
C) energy + carbon dioxide + water → glucose + oxygen
+ water
D) glucose → ethyl alcohol + carbon dioxide + energy
49) The energy released from glucose by the process
of cellular respiration is in the form of ______.
50) During cellular respiration, the energy in
glucose is ______.
A) transferred to starch B) carried by electrons C)
used to manufacture glucose by exergonic reactions
51) During redox reactions, ______.
A) the loss of electrons from one substance is
called reduction
B) electrons are lost from one substance and added
to another substance
C) a substance that gains electrons is said to be
oxidized
D) protons from one molecule replace the electrons
lost from another molecule
52) Which of the following statements is completely
true?
A) Lactic acid is a product of aerobic respiration;
ethyl alcohol is a product of fermentation.
B) Oxygen is a product of cellular respiration;
carbon dioxide is a product of photosynthesis.
C) Oxidation is the loss of electrons; reduction is
the gain of electrons.
D) Glucose is a product of aerobic respiration;
lactic acid is a product of anaerobic respiration.
53) The final electron acceptor of aerobic
respiration is ______.
54) A product of glycolysis is ______.
55) Where in the cell does glycolysis occur?
A) along the outside of the outer mitochondrial
membrane B) ER C) cytosol
D) between the inner and outer mitochondrial
membrane
E) within the fluid just inside the inner
mitochondrial membrane
56) Which of the following is a correct sequence of
stages in cellular respiration?
A) citric acid cycle, glycolysis, electron transport
chain
B) electron transport chain, citric acid cycle,
glycolysis
C) citric acid cycle, electron transport chain,
glycolysis
D) electron transport chain, glycolysis, citric acid
cycle
57) What must pyruvic acid be converted to before it
can enter the citric acid cycle?
A) ethyl alcohol B)
acetyl CoA C) citric acid D) NADH E)
lactic acid
58) Energy is transferred from ATP to other
molecules by transferring a(n) ______.
A) adenosine B)
phosphate group C) heat D) photon E) spring
59) Which part of cellular respiration produces the
most NADH?
A) electron transport chain B) Calvin cycle C) citric
acid cycle D) hydrogenation E) glycolysis
60) In cellular respiration, most ATP is produced
directly as a result of ______.
A) glycolysis B)
the electron transport chain C)
fermentation D) the citric acid
cycle
E) the movement of hydrogen ions across the inner
mitochondrial membrane
61) Anaerobic respiration produces a maximum of
______ ATP per glucose.
A) 36 B)
4 C) 2 D) 38 E) 10
62) Some friends are trying to make wine in their
basement. They've added yeast to a sweet grape juice mixture and have allowed
the yeast to grow. After several days they find that sugar levels in the grape
juice have dropped, but there's no alcohol in the mixture. The most likely
explanation is that ______.
A) the mixture needs less oxygen; yeast only produce
alcohol in the absence of oxygen
B) the mixture needs less sugar; high sugar
concentrations stimulate cellular respiration, and alcohol is not a by-product
of cellular respiration
C) the mixture needs more oxygen; yeast need oxygen
to break down sugar and get enough energy to produce alcohol
D) the mixture needs more sugar; yeast need a lot of
energy before they can begin to produce alcohol
E) none of the above
63) What waste product do yeast produce under
anaerobic conditions?
A) ethyl alcohol B)
lactic acid C) pyruvic acid
D) creatine E) glucosamine
64) If you were able to stop the process of cellular
respiration after completion of electron transport but prior to chemiosmosis,
you would find the pH of a mitochondrion to be at its lowest ______.
A) in the cytoplasm B)
on the inner membrane C) in the
intermembrane space
D) in the mitochondrial matrix E) on the outer membrane
This graph
represents an exergonic reaction with and without an enzyme catalyst.
65) Which letter represents the ΔG of the reaction?
66) Which letter represents the activation energy
required for the enzyme-catalyzed reaction?
67) Which letter represents the activation energy
required for a noncatalyzed reaction?
68) Which letter represents the difference between the free-energy content of the reaction and the free-energy content of the products?
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