229 Exam 1 Practice Questions
Name___________________________________
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) Robert Hooke coined the term cell when studying thin slices of cork. These ________ were the
first cells observed because ________.
A) "little rooms"; they were 100 nm in diameter, much larger than most plant cells
B) dead plant cells; the thick cells walls did not require high resolution or magnification to
view
C) dead animal cells; they were immobile and did not need to be fixed before viewing
D) immune cells; they produce antibodies that embed in the cell membrane to make it visible
E) compartments; they were actually the result of multiple cells that had merged and died to
form large compartments that were easy to view
1)
2) Which organelle stores most of the DNA in plant and animal cells?
A) nucleus
B) lysosome
C) Golgi complex
D) chloroplast
E) mitochondrion
2)
3) Which of the following statements is false ?
A) All cells have a membrane -bound nucleus.
B) Cells come in a wide variety of sizes and shapes.
C) All organisms consist of one or more cells.
D) All cells arise from preexisting cells.
E) The cell is the basic unit of structure for all organisms.
3)
4) Which of the following is true of a nanometer?
A) A nanometer is about the size of a common bacterial cell.
B) The nanometer is the most common measurement used in measuring whole cells.
C) A nanometer is equivalent to 10 Angstroms (Å).
D) A nanometer is one millionth of a meter.
E) None of the above.
4)
5) Cell biology emerged from which of the following fields of biology?
A) cytology
B) biochemistry
C) biochemistry, cytology, and genetics
D) cytology and biochemistry
E) genetics
5)
6) Which of the following is smallest?
A) protein
B) ribosome
C) prokaryote
D) virus
E) mitochondrion
6)
1
7) You are working on a project that involves the direct observation of DNA molecules. The
microscope that would give you the best information at this time would be the
A) transmission electron microscope.
B) light microscope.
C) digital video microscope.
D) fluorescent microscope.
E) phase -contrast microscope.
7)
8) The limit of resolution can best be defined as
A) the inverse of the wavelength of light; it is greatest for black light.
B) the magnification power of a microscope.
C) the distance that an object must be moved to be distinguished from its background.
D) the solvent that must be available to remix a solution.
E) the distance that two objects must be apart to be distinguished as separate objects.
8)
9) Which of the following is an application of immunofluorescence microscopy?
A) Identifying which organelle or cellular compartment contains a particular protein.
B) Visualization of the surface structures of a specimen.
C) Construction of three -dimensional images of structures smaller than 10 nm.
D) Visualization of the natural fluorescence of a specimen under UV light.
E) Identification of specific components of the immune system.
9)
10) Which type of microscopy has the greatest resolving power?
A) fluorescence microscopy
B) confocal scanning microscopy
C) electron microscopy
D) digital video microscopy
E) phase -contrast microscopy
10)
11) Which of the following types of light microscopy improves the resolution of thick specimens by
illuminating one plane of the specimen at a time?
A) phase -contrast microscopy
B) differential interference contrast microscopy
C) fluorescence microscopy
D) confocal microscopy
E) brightfield microscopy
11)
12) You wish to obtain a purified sample of mitochondria from lysed cells. The best way to obtain
this sample would be
A) centrifugation.
B) chromatography.
C) both centrifugation and polyacrylamide gel electrophoresis.
D) agarose gel electrophoresis.
E) polyacrylamide gel electrophoresis.
12)
2
13) Which of the following biochemical techniques uses an electrical field to separate
macromolecules based on their mobility through a semisolid gel?
A) electrophoresis.
B) light microscopy.
C) chromatography.
D) mass spectrometry.
E) ultracentrifugation.
13)
MATCHING. Choose the item in column 2 that best matches each item in column 1.
Match the type of microscopy with the appropriate characteristic.
14) brightfield
A) detects electrons passing through a
specimen
15) fluorescence
14)
15)
B) shows specific molecules
16) phase -contrast
16)
C) amplifies variations in density
17) confocal
18) transmission electron microscopy
19) scanning electron microscopy
17)
D) uses a laser to view a single plane of a
specimen
E) detects electrons deflected from the
surface of the specimen
F) light passes directly through specimen
3
18)
19)
Match the organelle to its function.
20) nucleus
A) detoxification of hydrogen peroxide
20)
21) mitochondrion
B) protein synthesis
21)
22) chloroplast
C) ATP synthesis
22)
23) nucleolus
D) contains pigments in flowers
23)
24) rough endoplasmic reticulum
E) cell shape and movement of organelles
24)
25) cytoskeleton
F) storage of hydrolase
25)
26) chromoplast
G) information center
26)
27) Golgi complex
H) synthesis of secretory proteins
27)
28) lysosome
I) ribosome production
28)
29) peroxisome
J) turgor pressure
29)
30) central vacuole
K) synthesis of complex polysaccharides
30)
31) ribosome
L) photosynthesis
31)
32) plasma membrane
M) boundary of the cell
32)
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
33) Which of the following is characteristic of eukaryotic cells?
A) smaller than 5 µm in diameter
B) 70S ribosomes
C) binary fission
D) peptidoglycan cell wall
E) membrane -bounded nucleus
33)
34) The methanobacteria, halobacteria, and sulfobacteria are included in which domain?
A) protista
B) bacteria
C) archaea
D) eukarya
E) blue-green algae
34)
4
35) The size range of most plant and animal cells is
A) 50—100 mm.
B) 1—10 nm.
C) 0.1—0.5 mm.
D) 10—50 !m.
E) 1—5 !m.
35)
36) Which of the following is true of plant cells?
A) Plant cells may contain chloroplasts.
B) Plant cells are always much larger than animal cells.
C) The plant cell has no cell wall.
D) Chromosomes are found only in plant cells.
E) Only plant cells have a cell membrane.
36)
37) Which of the following organelles is not generally found in animal cells?
A) centriole
B) central vacuole
C) food vacuole
D) endoplasmic reticulum
E) mitochondrion
37)
38) When the size of a cell increases, the surface area/volume ratio
A) increases initially and then begins to decrease.
B) decreases.
C) increases.
D) decreases initially and then begins to increase.
E) remains the same.
38)
39) Which of the following would be attributed to a peroxisomal dysfunction?
A) accumulation of very long chain fatty acids
B) accumulation of ganglioside GM2
39)
C) accumulation of complex sugars
D) accumulation of N-acetylglucosamine phosphotransferase
E) accumulation of glucocerebroside
40) Membrane proteins may function in
A) temperature control.
B) information storage.
C) amphipathic modification.
D) receiving extracellular signals.
E) protein manufacture.
40)
41) Which of the following is least likely to be part of a cell membrane?
A) enzymes
B) peptidoglycans
C) phospholipids
D) glycoproteins
E) transport proteins
41)
5
42) The smooth endoplasmic reticulum functions in synthesis of
A) DNA.
B) lipids.
C) proteins.
D) polysaccharides.
E) lipids, polysaccharides, proteins, and DNA.
42)
43) Which of the following processes would be most likely to occur in the Golgi complex?
A) synthesis of DNA
B) production and packaging of lipids
C) glycosylation of proteins
D) synthesis of steroids
E) detoxification of drugs
43)
44) Which sequence reflects the locations that a secretory protein will visit on its way from its
production to its secretion outside the cell?
A) rough ER, ER vesicle, Golgi complex, secretory vesicle
B) rough ER, secretory vesicle, Golgi complex, ER vesicle
C) rough ER, Golgi complex, smooth ER, ER vesicle
D) smooth ER, rough ER, Golgi complex, secretory vesicle
E) nucleus, Golgi complex, rough or smooth ER, secretory vesicle
44)
45) Intermediate filaments are
A) composed of tubulin.
B) different in different cell types.
C) composed of globular proteins only.
D) smaller than actin filaments.
E) None of these are correct.
45)
46) The major structural elements of the cytoskeleton are
A) the extracellular matrix and the cell wall.
B) microtubules, microfilaments, and intermediate filaments.
C) cleavage furrows and G-actin.
D) proteoglycans and cellulose microfibrils.
E) the cytoplasm and cytosol.
46)
47) Communication between animal cells is facilitated by
A) tight junctions.
B) gap junctions.
C) plasmodesmata.
D) gap and adhesive junctions.
E) adhesive junctions.
47)
48) The main role of the central vacuole in plant cells is to
A) digest trapped food particles.
B) maintain turgor pressure in plant tissue.
C) synthesize and store proteins.
D) catalyze photorespiration in association with chloroplasts.
E) store glycogen for seed growth.
48)
6
49) In which of the following properties are the archaea more like eukaryotes than the bacteria?
A) mode of cell division
B) both translation initiation and mode of cell division
C) microtubules and microfilaments
D) translation initiation
E) size
49)
50) An enzyme
A) does not change the rate at which the equilibrium is achieved.
B) changes the position of the equilibrium of the reaction.
C) binds substrates in a manner that facilitates the formation of product.
D) decreases the rate of a reaction.
E) is always a protein.
50)
51) The extracellular matrix outside the plasma membrane of animal cells is typically composed of
A) collagen, proteoglycans, lipids, and peptidoglycan.
B) cellulose.
C) collagen and proteoglycans.
D) peptidoglycan.
E) lipids.
51)
52) The chromoplast is an organelle associated with
A) storage of chromium.
B) plant pigment storage.
C) ribosome production in primitive plants.
D) oxidation of sugars.
E) synthesis of secretory proteins.
52)
53) Individuals with the O blood group are known as universal donors because the Gal and GlcNAc
groups that are recognized by the antibodies in A, B, and AB in other individuals are missing.
Which of which of the following types of erythrocyte plasma membrane components lacks these
GlcNAc groups?
A) a glycolipid
B) a glycoprotein
C) a glycocalyx protein
D) glycophorin
E) a GPI-anchored protein
53)
54) Naturally occurring unsaturated fatty acids typically
A) are omega-3 fatty acids.
B) are highly branched.
C) contain double bonds primarily in the trans configuration.
D) contain double bonds primarily in the cis configuration.
E) contain an odd number of carbon atoms.
54)
7
55) Which of the following would best be used to determine the lipid content of an isolated
membrane fraction?
A) freeze -fracture analysis
B) ferretin-linked antibodies
C) SDS-PAGE
D) thin-layer chromatography
E) Western blot analysis
55)
56) Each of the following is a function of membranes except
A) regulation of transport.
B) information storage.
C) sites for specific biochemical functions.
D) defining cell and organelle boundaries.
E) cellcell communication.
56)
57) In response to temperature changes, cell membranes change state to become more solid or more
fluid by undergoing
A) membrane folding.
B) transverse diffusion.
C) differential scanning calorimetry.
D) lipid raft formation.
E) a phase transition.
57)
58) When a mouse cell and a human cell with different cell-surface protein markers are fused using
polyethylene glycol (PEG) and immediately placed at 0°C, what would you expect happens to
the mouse and human marker proteins?
A) The mouse and human markers will migrate to opposite poles of the fused membrane.
B) Only the mouse cell marker proteins will disperse throughout the fused membrane; the
human marker proteins will remain confined to the original human region of the fused
membrane.
C) Both mouse and human markers will be endocytosed by the fused cell and destroyed in
the fused cell.
D) Both the mouse and human marker proteins will rapidly disperse evenly throughout the
fused membrane.
E) The mouse and human markers will migrate little and remain confined to their original
membrane regions.
58)
59) Of the following molecules, which would you predict diffuses most readily across membranes?
A) serine
B) oxygen
C) water
D) hydrogen ions
E) glucose
59)
60) Each of the following is a type of cellcell junctions except
A) plasmodesmata.
B) tight.
C) gap.
D) adhesive.
E) All are cellcell junctions.
60)
8
61) The composition of lipids in the outer and inner monolayers of cell membrane lipid bilayers is
A) twice as concentrated in the inner monolayer as in the outer monolayer.
B) the same for all cell plasma membranes but different from the composition in
mitochondrial and chloroplast membranes.
C) identical in each monolayer.
D) asymmetrical; i.e., different in each monolayer.
E) highly random for each monolayer.
61)
62) The most prominent lipids in animal cell membranes are
A) phospholipids.
B) phytosterol.
C) cerebrosides.
D) glycolipids.
E) cholesterol.
62)
63) Which of the following lipids is found concentrated in lipid rafts in animal cell plasma
membranes?
A) phosphatidylserine
B) cholesterol
C) phosphatidylinositol
D) phophatidylethanolamine
E) phosphatidylcholine
63)
64) Cholesterol
A) increases permeability for Ca2+.
B) buffers membrane fluidity by increasing fluidity at low temperature and decreasing
fluidity at high temperature.
C) increases permeability for small polar molecules.
D) is found in abundance in prokaryotic cell membranes.
E) All of the above are correct.
64)
65) Using a laser beam to inactivate fluorescence dye molecules connected to proteins or lipids on a
cell membrane is called
A) liposome formation.
B) freeze -fracturing.
C) electrophoresis.
D) affinity labeling.
E) photobleaching.
65)
66) Which of the following is a sterol-like lipid associated with plant cell membranes?
A) phytosterol
B) palmitate
C) hopanoids
D) linoleate
E) stearate
66)
9
67) Lipid rafts are associated with which of the following activities?
A) responding to extracellular signals
B) transport of cholera toxin into cells
C) transport of nutrients across cell membranes
D) immune responses
E) All of the above are correct.
67)
68) The technique that separates denatured proteins based on size is
A) thin-layer chromatography.
B) freeze -fracture microscopy.
C) SDS-PAGE.
D) FRAP.
E) Western blotting.
68)
69) Localized regions of plasma membranes that contain cholesterol and proteins involved in cell
signaling are known as
A) arterial plaques.
B) plasmodesmata.
C) gap junctions.
D) cadherin junctions.
E) lipid rafts.
69)
70) The number and location of transmembrane segments in an integral membrane protein can be
inferred from the amino acid sequence of the protein by a computer-generated
A) Western blot.
B) DNA sequence.
C) hydropathy plot.
D) freeze -fracture replica.
E) prediction of glycosylation sites.
70)
71) Cell—cell communication in plants takes place via specialized structures called
A) lipid rafts.
B) chloroplast outer membrane pores.
C) gap junctions.
D) plasmodesmata.
E) connexons.
71)
72) Each of the following molecules move across membranes by simple diffusion except
A) carbon dioxide.
B) glucose.
C) water.
D) oxygen.
E) fatty acids.
72)
73) One way in which ions are specifically transported into the cell is via
A) uniport transporters.
B) ABC transporters.
C) gated channels.
D) carrier (permease) proteins.
E) simple diffusion.
73)
10
74) Which of the following protein types would you predict is defective in kidney water balance
disorders?
A) GLUT
B) porin
C) class ATPase
D) aquaporin
E) anion exchange protein
74)
75) Phosphorylation of glucose following its transport into a cell
A) decreases glucose transport into the cell by decreasing its concentration gradient across
the plasma membrane.
B) targets the glucose for transport back out of the cell.
C) increases glucose transport into the cell by increasing its concentration gradient across the
plasma membrane.
D) converts glucose into a form that can more easily be exported from the cell.
E) maintains a higher level of glucose outside the cell.
75)
76) Water moves across the plasma membrane into or out of a cell by osmosis when
A) water diffuses through a semipermeable membrane toward a higher solute concentration.
B) there is an equal solute concentration on both sides of the membrane.
C) ATP hydrolysis drives aquaporin transport.
D) a high solute concentration opens an aquaporin channel.
E) water diffuses through a semipermeable membrane toward a lower solute concentration.
76)
77) Which of the following types of transport occur across the erythrocyte membrane?
A) O 2 and CO 2 passive diffusion
77)
B)
C)
D)
E)
Cl− bicarbonate ion antiport
aquaporin water transport
glucose uniport
All of the above are correct.
78) Because the procedure you are using to modify plants requires their cell membranes to be pulled
away from the cell walls by plasmolysis, you place the cells in a(n)
A) isotonic solution.
B) hypotonic solution.
C) hypertonic solution.
D) acid solution.
E) basic solution.
78)
79) Which of the following is a characteristic of facilitated diffusion (passive transport) of a molecule
across a membrane?
A) It is highly specific for the molecule being transported.
B) Its rate is higher than that of simple diffusion of the molecule.
C) The direction of transport is determined by concentration and/or electrochemical
gradients.
D) The rate of transport is saturable.
E) All of the above are true.
79)
11
80) Each of the following is an example of facilitated diffusion except
A) chloride -bicarbonate exchange.
B) aquaporin transport.
C) glucose transport by GLUT1.
D) ion channel transport.
E) oxygen transport.
80)
81) Each of the following is true for the mechanism of the Na+/K+ ATPase pump except
A) Each E1-E2 cycle pumps 3 Na+ ions out and 2 K+ ions in.
B) K+ triggered dephosphorylation of the pump stabilizes the E2 conformation.
C) the E1 conformation is open to the inside of the cell and has high affinity for Na+.
D) the E2 conformation is open to the outside of the cell and has high affinity for K+.
E) Na+ triggered phosphorylation of the pump stabilizes the E2 conformation.
81)
82) Cystic fibrosis is the result of a malfunction of a cellular ABC transporter that transports
A) vitamin B12.
82)
B)
C)
D)
E)
Cl−.
a hydrophobic drug.
amino acids.
glucose.
83) Each of the following is a characteristic of active transport mechanisms except
A) coupling transport of a solute down its concentration with transport of another solute up
its concentration gradient via a symport or antiport mechanism..
B) sensitivity to inhibitors such as proton pump inhibitors.
C) coupling a thermodynamically unfavorable (endergonic) process with a favorable
(exergonic) process.
D) nondirectionality for moving a solute in either direction across a membrane depending on
the solute concentration gradient.
E) moving solutes away from equilibrium across a membrane.
83)
84) Binding and hydrolysis of ATP in a "cassette" domain is part of the transport mechanism of
which of the following types of transporters?
A) V type
B) P type
C) ABC type
D) type
E) All of the above are correct.
84)
85) The Na +/K+ ATPase pump actively moves
A) 2 Na+ in, 3 K+ out.
B) 3 Na+ out, 2 K+ in.
C) 2 Na+ out, 3 K+ in.
D) 1 Na+ out, 1 K+ in.
E) 3 Na+ in 2 K+ out.
85)
12
86) Which of the following is an example of indirect active transport?
A) Na+/K+ ATPase
B) glucose permease transport
C) aquaporin water transport
D) CFTR Cl− transport
E) Na+/glucose symport
86)
87) The primary difference between active transport and facilitated diffusion is that active transport
is the only one of the two in which
A) the direction of transport is [S]high → [S]low.
B) the S concentration gradient provides the energy necessary for S transport.
C) transporter proteins are required.
D) the mechanism is not saturable.
E) the direction of transport is [S]low → [S]high.
87)
88) ABC-type ATPases that inhibit the effectiveness of antitumor drugs by transporting the drugs
out of tumor cells are known as
A) multidrug resistance (MDR) transporters.
B) porins.
C) the cystic fibrosis transmembrane conductance regulator (CFTR).
D) Na+-drug antiporters.
E) None of the above; no such transporter has been identified in eukaryotes.
88)
89) Active transport makes it possible for cells to
A) establish an electrical potential across the membrane.
B) take up nutrients from the environment against concentrations gradients.
C) transport out secretory products and waste material against concentration gradients.
D) maintain nonequilibrium intracellular concentrations of ions such as Na+, K+, Ca2+, and
H+.
E) All of the above are correct.
89)
90) Which of the following types of ATPase pumps are sensitive to vanadate (which inhibits
phosphorylation of the pump during its activity mechanism)?
A) P type
B) ABC type
C) F type
D) V type
E) All are inhibited by vanadate.
90)
91) Which of the following types of work involves a change in position of the cell or a cell structure?
A) mechanical
B) concentration
C) electrical
D) synthetic
E) bioluminescent
91)
13
92) Animals that regulate their body temperature independently of the environment are called
A) homeotherms.
B) poikilotherms.
C) biotherms.
D) abiotherms.
E) heterotherms.
92)
93) Muscle contraction is an example of which of the following types of work?
A) electrical
B) concentration
C) heat
D) bioluminescent
E) mechanical
93)
94) Fireflies have the ability to convert the energy in ATP to light. Which of the following types of
work is performed by the firefly?
A) heat
B) electrical
C) bioluminescent
D) mechanical
E) concentration
94)
95) Which of the following is defined as "heat content"?
A) energy output
B) entropy
C) heat loss
D) enthalpy
E) solar radiation
95)
96) Bioenergetics can be simply defined as
A) a subdivision of biology.
B) holding constant the variables in the universe.
C) applied thermodynamics.
D) the units in which energy is expressed.
E) the application of biological principles to physics.
96)
97) Nerve impulses travel along neurons by the opening of channels that allow sodium ions to flow
inward, followed by an outward flow of potassium ions. In order to ensure that the impulse may
be produced at any time, sodium is actively transported out of the cell and potassium is
transported into the cell by the sodium/potassium pump. Which of the following types of work
is performed by the sodium/potassium pump?
A) electrical
B) bioluminescent
C) concentration
D) mechanical
E) synthetic
97)
14
98) Energy-requiring reactions can occur in biological systems because they can be coupled with
reactions that are
A) unlikely.
B) not spontaneous.
C) spontaneous and endergonic.
D) exergonic.
E) endergonic.
98)
99) Reduction involves the
A) loss of neutrons, gain of electrons, and an increase in oxidation state.
B) loss of neutrons.
C) increase in oxidation state.
D) gain of electrons and an increase in oxidation state.
E) gain of electrons.
99)
100) Oxidation
A) is rare in biological reactions.
B) occurs when an atom accepts electrons.
C) is endothermic.
D) involves the removal of oxygen atoms from a molecule.
E) occurs when oxygen atoms are added to a molecule and energy released.
100)
101) Which is true of heterotrophs?
A) They cannot be unicellular.
B) They can obtain energy by consuming phototrophs.
C) They capture light energy.
D) They store energy in the form of heat.
E) They can function as autotrophs in an emergency.
101)
102) In a biochemical reaction, reactants may be converted into products. The extent to which this
occurs spontaneously is expressed as which of the following?
A) ∆S
B) T∆S
C) ∆G
D) temperature
E) K
eq
102)
103) Energy is important to life forms because
A) energy is required to make specific alterations in the cell.
B) all life forms require a continuous supply of energy.
C) all life forms require a continuous supply of energy, energy is required to do work, and
energy is required to make specific alterations in the cell.
D) energy is required to do work.
E) all life forms require a continuous supply of energy and energy is required to do work.
103)
15
104) Under the conditions of a given reaction, a positive ∆G' means
A) the reaction will not occur.
B) the reaction is spontaneous.
C) work can be done.
D) the reaction is at equilibrium.
E) no energy needs to be added.
104)
105) Which process involves an increase in entropy of the system?
A) combustion of paper
B) freezing of ice
C) synthesis of cellulose
D) formation of raindrops
E) any spontaneous process
105)
106) When ∆G' = 0 in a chemical reaction, under standard conditions,
A) work can be done; energy is required.
B) reactants and products are at equilibrium.
C) reactants and products are at equilibrium; no work can be done; no energy required.
D) no work can be done; no energy is required.
E) the reaction is spontaneous to the left.
106)
107) Which of the following is not a basic need of the cell?
A) energy
B) molecular building blocks
C) information
D) chemical catalysts
E) 100% efficiency
107)
108) A spontaneous reaction
A) will never occur.
B) has to occur immediately.
C) has an overall positive free energy change.
D) is associated exclusively with homeothermic organisms.
E) could occur but might take a very long time.
108)
109) A negative free energy change indicates that
A) the reaction is at equilibrium.
B) the reaction is not possible.
C) the reaction is exothermic.
D) energy must be added to the reaction before it can proceed.
E) the reactant is predominant at equilibrium.
109)
110) In a chemical reaction, the standard free energy change (∆G°') is calculated to be 3.67 cal/mol.
What can be said of the chemical reaction?
A) The reaction is at equilibrium under standard conditions.
B) The reaction is not spontaneous under standard conditions.
C) Products predominate over reactants at equilibrium under standard conditions.
D) The reaction goes spontaneously to the right under standard conditions.
E) There can be no reaction.
110)
16
111) In a reversible chemical reaction at equilibrium, the concentration of X (the reactant) is 0.75
mol/L, and the concentration of Y (the product) is 2.25 mol/L. At 25°C, what would be the K ?
eq
A) 3.0
B) 1.69
C) 37.5
D) 0.33
E) 1.50
111)
112) "The total amount of mass -energy in the universe is constant," is a statement of
A) entropy.
B) the first law of thermodynamics.
C) enthalpy.
D) the second law of thermodynamics.
E) thermodynamic spontaneity.
112)
113) Which of the following is a chemoheterotroph?
A) a tree
B) a mushroom
C) grass
D) a photosynthetic bacterium
E) algae
113)
114) Which of the following is a phototroph?
A) an earthworm
B) a mushroom
C) a person
D) soil bacterium
E) a tree
114)
MATCHING. Choose the item in column 2 that best matches each item in column 1.
Match the symbol with the appropriate definition to the right.
115) ∆S
A) change in size
115)
116) K
B) equilibrium constant
116)
eq
117) ∆H
118) ∆G
C) change in entropy
D) change in enthalpy
E) equation constant
F) change in gas pressure
G) change in stored energy
H) change in free energy
17
117)
118)
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
119) The site on an enzyme that will bind the substrate is called the
A) activation site.
B) metastable site.
C) prosthetic group.
D) catalyst.
E) active site.
119)
120) Which of the following is a mechanism of substrate activation?
A) proton transfer
B) electron transfer
C) bond distortion, proton transfer, and electron transfer
D) neutron transfer
E) bond distortion
120)
121) An enzyme is active in the stomach of an animal but quickly loses its activity when it leaves the
stomach. This example illustrates that enzymes are
A) sensitive to changes in pH.
B) inactivated by movement.
C) consumed by the quantities of substrate in the small intestine.
D) specific to the organs in which they are produced.
E) digested in the small intestine.
121)
122) A sick person often has a fever, which can inhibit the growth of bacteria because
A) sweating removes prosthetic groups from biological enzymes.
B) enzymes do not function as well at temperatures other than the optimal temperature.
C) fever blocks synthesis of proteins in the bacterial nucleus.
D) bacteria reproduce more rapidly at higher body temperature.
E) the higher temperature increases the activity of lyases.
122)
123) The rate of a reaction catalyzed by an enzymes usually ________ with temperature; however, at
temperatures above the optimum range ________.
A) decreases; prosthetic groups are necessary
B) decreases; the reaction proceeds without the enzyme
C) increases; the reaction proceeds without the enzyme
D) increases; protein denaturation occurs
E) increases; the direction of the reaction reverses
123)
124) The equation AB + H O → A + B would be catalyzed by which of the following classes of
2
enzymes?
A) oxidoreductases
B) isomerases
C) transferases
D) hydrolases
E) ligases
124)
18
125) A noncompetitive inhibitor will
A) decrease V
.
max
B) bind to free product.
C) bind to free enzyme.
D) bind to free enzyme and decrease V
.
max
E) decrease K .
m
125)
126) Saturation can be defined as
A) the substrate concentration at which velocity reaches one -half maximum velocity.
B) inhibition of enzyme function by blocking the active site.
C) the inability to increase reaction velocity beyond a finite upper limit.
D) a characteristic of all uncatalyzed reactions.
E) denaturation of an enzyme.
126)
127) Which of the following variables is not part of the MichaelisMenten equation?
A) V
B) v
C) k
D) [S]
max
cat
127)
E) K
m
128) An allosteric inhibitor
A) binds at the regulatory site.
B) is converted to an activator by the enzyme.
C) increases the rate of substrate binding.
D) binds and activates the high-affinity state of the enzymes.
E) is identical to the active site.
128)
129) Feedback inhibition prevents cells from
A) making products that are not needed by inhibiting the activity of enzymes in biosynthetic
pathways allosterically.
B) accumulating unnecessary proteins.
C) destroying enzymes by proteolytic cleavage when they are needed in biosynthetic
pathways.
D) irreversibly inhibiting critical enzymes.
E) the harmful effects of enzyme activation by covalent modification of unneeded enzymes.
129)
130) Why is the Lineweaver—Burk plot important in enzyme kinetics?
A) It illustrates enzyme specificity.
B) It reveals the presence of prosthetic groups in enzymes.
C) It makes it easier to determine V
and K
max
m.
D) It is nonlinear.
E) It is a single -reciprocal plot.
130)
131) The induced-fit model
A) distorts the shape of the enzyme and the substrate.
B) was proposed by Hans Buchner.
C) states that enzyme—substrate interactions are rigid.
D) is also called the lock-and-key model.
E) proposes that very strong covalent bonds are formed upon substrate binding.
131)
19
132) Which of the following is not true of the enzyme—substrate interaction?
A) Cells are often able to carry out metabolic activity with only a handful of enzymes
because many are nonspecific.
B) Many enzymes cannot recognize a stereoisomer of their substrate.
C) Some enzymes accept any of a whole group of substrates.
D) Carboxypeptidase recognizes any of the amino acids from the carboxyl end of a
polypeptide.
E) Many enzymes are extremely specific regarding a substrate.
132)
133) The type of inhibitor that binds to the enzyme active site is a(n) ________ inhibitor.
A) coenzyme
B) competitive
C) noncompetitive
D) mixed-type
E) uncompetitive
133)
134) A noncompetitive inhibitor will affect the ________ of an enzymatic reaction.
A) K
m
B) V
max
C) S
D) P
E) both K and V
m
max
134)
135) A competitive inhibitor will affect the ________ of an enzymatic reaction.
A) K
m
B) V
max
C) S
D) P
E) both K and V
m
max
135)
136) An enzyme reduces the free energy of which of the following?
A) substrate
B) intermediate product
C) product
D) transition state
E) cofactor
136)
137) Which of the following is a unit of energy?
A) calorie
B) bond
C) watt
D) mole
E) both A and B
137)
20
138) While fishing, you make the following observations:
a. Water spiders appear to be able walk on the surface of the water.
b. Flat rocks may be made to skip across the water.
Which of the following properties of water can explain these observations?
A) Water is an excellent solvent.
B) Water molecules are heavy.
C) Water molecules are cohesive.
D) Water molecules are polar.
E) Both B and C
138)
139) Why do ionic substances such as NaCl dissolve so readily in water?
A) NaCl is a very dry powder, and the water is able to soak into the salt.
B) The sodium ions repel the negative end of the water molecule.
C) Water molecules form spheres of hydration around the sodium and chloride ions.
D) The charged ends of the water molecules are able to surround the oppositely charged salt
ion.
E) Both C and D
139)
140) Which of the following is an informational macromolecule?
A) glycogen
B) polypeptide
C) DNA
D) starch
E) ATP
140)
141) Monomers are removed from polymers by ________ reactions.
A) neutralization
B) substitution
C) condensation
D) hydrolysis
E) redox
141)
142) Why is a selectively permeable membrane so important to living things?
A) Proteins will avoid a selectively permeable membrane.
B) The membrane may absorb several times its weight in cholesterol.
C) It allows cells to attach to adjacent tissues.
D) It provides a good barrier between the inside and outside of the cell.
E) All of the above.
142)
143) Which of the following biomolecules are long polymers of repeating monomers?
A) lipids
B) proteins
C) nucleic acids
D) polysaccharides
E) polysaccharides, nucleic acids, and proteins
143)
21
144) An enzyme synthesized in the laboratory is found to have little activity when compared to the
enzyme extracted from cell culture. Both enzymes were examined and have identical amino acid
composition. What is the best explanation for the lack of activity of the synthesized enzyme?
A) The synthetic enzyme was not made of amino acids.
B) The synthesized enzyme was not folded correctly because molecular chaperones were not
present.
C) Denaturation of the synthesized enzyme was not complete.
D) The van der Waals radius was altered during laboratory synthesis.
E) The ATP required for self-assembly was present in the cell extract but not in the
laboratory synthesis.
144)
145) Which of the following sequences correctly lists the hierarchical nature of cellular structures,
from smallest to largest?
A) organic molecules, macromolecules, organelles, supramolecular structures, cells
B) organic molecules, macromolecules, supramolecular structures, organelles, cells
C) macromolecules, organic molecules, supramolecular structures, organelles, cells
D) organic molecules, supramolecular structures, macromolecules, organelles, cells
E) organelles, organic molecules, supramolecular structures, macromolecules, cells
145)
146) Which of the following macromolecules is insoluble in water?
A) amino acids
B) nucleic acids
C) disaccharides
D) lipids
E) sugars
146)
147) Which of the following is a structural polysaccharide?
A) starch
B) cellulose
C) fructose
D) glycogen
E) All of the above are structural polysaccharides.
147)
148) Which of the following statements about the polymerization of macromolecules is false?
A) A monomer is usually activated by the coupling of the monomer to a carrier.
B) The polymer chain usually has two different ends.
C) Water is added to join the monomers of the macromolecules.
D) Macromolecules are synthesized by the stepwise addition of monomers.
E) Often the energy needed for polymerization is supplied by ATP.
148)
149) Which one of the following biological polymers is mismatched with its monomer?
A) enzyme - amino acid
B) cellulose - amino acid
C) chitin - monosaccharide
D) protein - amino acid
E) DNA - nucleotide
149)
22
150) The cell membrane can be described most accurately as
A) impermeable to all polar molecules.
B) permeable to all molecules except water.
C) impermeable to larger molecules independent of their chemical characteristics.
D) permeable to all small molecules and ions.
E) permeable to some molecules and impermeable to others.
150)
151) How do large polar and charged molecules cross biological membranes?
A) Large polar and charged molecules can't cross biological membranes.
B) Large polar and charged molecules must be hydrolyzed before they can cross a biological
membrane.
C) Large polar and charged molecules cross biological membranes via diffusion through the
hydrophilic core of the membrane.
D) Large polar and charged molecules cross biological membranes via transport proteins that
form hydrophilic channels through the membrane.
E) Both A and C
151)
152) Which of the following molecules is most likely to cross the cell membrane directly by passive
diffusion?
A) insulin (a polypeptide)
B) Na+
152)
C) a steroid hormone (a hydrocarbon)
D) fructose (a sugar)
E) fructose and insulin
153) What are the three general types of amino acids?
A) positive, negative, and noncharged
B) α helices, β sheets, and looped segments
C) hydrophobic, polar (noncharged), polar (charged)
D) covalent, noncovalent, and van der Waals forces
E) acidic, basic, and neutral
153)
154) Disulfide bonds are often found to stabilize which of the following levels of protein structure?
A) secondary
B) primary
C) tertiary
D) primary, secondary, and tertiary
E) None of these structures involve disulfide bonds.
154)
155) A peptide bond
A) is a covalent bond between the carboxyl carbon of one amino acid and the amino nitrogen
of a second amino acid.
B) is a covalent bond between the NH group of one polypeptide and the CO group of an
adjacent polypeptide that holds together multimeric proteins.
C) is a covalent bond between adjacent glucose molecules in a peptide.
D) is a noncovalent bond that dictates the tertiary structure of a protein.
E) is a covalent bond between the functional R groups of adjacent amino acids.
155)
23
156) You are investigating the structure of the seeds of a newly discovered tropical plant. There is
storage material inside the seed. You treat the seed with peptidase (an enzyme that breaks
peptide bonds), glycoside hydrolases (an enzyme that breaks β glycosidic bonds), and amylase
(an enzyme that breaks α glycosidic bonds). Only the amylase appears to dissolve the storage
material in the seed. What does this tell you about the identity of the storage material?
A) The seed contains lipids to store carbon and energy.
B) The seed contains globular proteins to store carbon and energy.
C) The seed contains fibrous proteins to store carbon and energy.
D) The seed contains cellulose to store carbon and energy.
E) The seed contains starch to store carbon and energy.
156)
157) Cellulose belongs to which of the following groups of macromolecules?
A) nucleic acids
B) proteins
C) lipids
D) carbohydrates
E) none of these
157)
158) Which of the following pairs correctly matches the monomer with its polymer?
A) nucleotides; nucleic acids
B) terpenes; nucleic acids
C) peptides; proteins
D) amino acids; polysaccharides
E) glucose; proteins
158)
159) Complementary relationships between purines and pyrimidines
A) allow adenine to form two hydrogen bonds with thymine (or uracil) and guanine to form
three hydrogen bonds with cytosine to form double-stranded nucleic acids.
B) provide highly ordered, repetitive bonding to form α helices and β sheets within proteins.
C) allow adjacent bases in a nucleotide chain to stack tightly, stabilizing the DNA double
helix.
D) allow the interaction of the oppositely charged amino acids to form the tertiary structure
of proteins.
E) Both A and C are correct.
159)
160) RNA and DNA differ
A) in that RNA contains uracil and DNA contains thymine.
B) in that RNA contains nucleosides and DNA contains nucleotides.
C) in that RNA contains ribose and DNA contains deoxyribose.
D) both A and C.
E) All of these are correct.
160)
161) The two strands of DNA are held together by ________; thus ________.
A) hydrophobic interactions; double-stranded DNA separates into two separate strands
when dissolved in a hydrocarbon (hydrophobic) solvent
B) hydrogen bonds; double -stranded DNA separates into two separate strands at high
temperatures
C) antiparallel bonds; double-stranded DNA is amphipathic
D) covalent bonds; double -stranded DNA is very stable at a range of temperatures
E) ionic bonds; double-stranded DNA separates into two separate strands in water
161)
24
162) Cholesterol is a ________, which ________.
A) steroid; is a component of eukaryotic membranes
B) fatty acid; functions in energy storage
C) terpene; is the basis for many animal and plant vitamins
D) steroid; is a component of eukaryotic membranes and is the basis for many animal and
plant hormones
E) steroid; is the basis for many animal and plant hormones
162)
163) Which of the following is true of purines?
A) Adenine's bonding to thymine is stronger than is guanine's to cytosine.
B) Purines bind readily to deoxyribose but not to ribose.
C) Purines have a double -ringed structure.
D) Both adenine and thymine are purines.
E) Cytosine is a purine.
163)
164) Which of the following statements is true ?
A) Hormones are unsaturated fatty acids.
B) Unsaturated fatty acids are usually branched.
C) Saturated fatty acids have no double bonds between carbons.
D) Fatty acids are synthesized by the stepwise addition of three carbon units.
E) Fatty acids with 24 carbons are most common.
164)
165) Which of the following is true of glycolipids?
A) Fructose and sucrose are often part of glycolipids.
B) Usually more than 10 sugar units are attached to the glycolipid.
C) Glycolipids are found in plastids and are used to store energy.
D) Glycolipids contain steroids.
E) Glycolipids are usually found on the exterior surface of the plasma membrane.
165)
166) Which of the following is not a steroid?
A) cortisol
B) phenylalanine
C) estradiol
D) testosterone
E) aldosterone
166)
167) Which of the following is not a polymer of numerous monomer units?
A) a phospholipid
B) cellulose
C) a polypeptide
D) an RNA molecule
E) starch
167)
25
168) Lipid rafts are
A) regions where greater concentrations of sphingolipids are on the inner side of the
membrane.
B) regions of the membrane that are high in sphingolipids, which facilitate communication
with the external environment of the cell.
C) important regions of membrane structure comprised of phospholipids.
D) regions not typically associated with signal transduction.
E) rafts of lipids inside of the cell that serve to store energy.
168)
169) The chemical nature of each amino acid is determined by which of the following groups?
A) hydrogen
B) amino
C) carboxyl
D) R
E) hydroxyl
169)
170) The nucleoside triphosphate molecules in DNA are linked together in the 5'→3' by a(n) ________
bridge.
A) phosphodiester
B) peptide
C) phosphatidyl
D) covalent
E) phosphate
170)
171) The components of a nucleotide are
A) a three -carbon alcohol with a hydroxyl group on each carbon and three fatty acids.
B) a six-carbon sugar, an ester linkage, and a four-ringed hydrocarbon.
C) two six-carbon sugars attached with an α(1→4) glycosidic bond.
D) a carboxyl group, an amine group, and a variable R group.
E) a five-carbon sugar, a phosphate group, and a nitrogen-containing aromatic base.
171)
26