Test Bank For Principles Of Biochemistry, 4th Edition

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Contents
Chapter 1 Introduction to Biochemistry 1
Chapter 2 Water 10
Chapter 3 Amino Acids and the Primary Structures of Proteins 27
Chapter 4 Proteins: Three-Dimensional Structure and Function 46
Chapter 5 Properties of Enzymes 65
Chapter 6 Mechanisms of Enzymes 85
Chapter 7 Coenzymes and Vitamins 104
Chapter 8 Carbohydrates 119
Chapter 9 Lipids and Membranes 137
Chapter 10 Introduction to Metabolism 153
Chapter 11 Glycolysis 169
Chapter 12 Gluconeogenesis, The Pentose Phosphate Pathway,
and Glycogen Metabolism 185
Chapter 13 The Citric Acid Cycle 199
Chapter 14 Electron Transport and Oxidative Phosphorylation 213
Chapter 15 Photosynthesis 227
Chapter 16 Lipid Metabolism 241
Chapter 17 Amino Acid Metabolism 256
Chapter 18 Nucleotide Metabolism 269
Chapter 19 Nucleic Acids 284
Chapter 20 DNA Replication, Repair, and Recombination 300
Chapter 21 Transcription and RNA Processing 315
Chapter 22 Protein Synthesis 330
Chapter 23 Recombinant DNA Technology 348

Chapter 1 Introduction to Biochemistry
1) Which elements account for more than 97% of the weight of most organisms?
A) C, H, N, Mg, O, S
B) C, H, N, O, P, S
C) C, H, N
D) Fe, C, H, O, P
E) Ca2+, K+, Na+, Mg2+, Cl-
Answer: B
Page Ref: Section 2
2) Proteins in biological membranes may be
A) porous.
B) attached to the membrane surface.
C) span the membrane.
D) All of the above
E) B and C only
Answer: D
Page Ref: Section 3
3) Which statement about cellulose is false?
A) It is the most abundant polysaccharide in nature.
B) Its monomers are joined by glycosidic bonds.
C) It is present in the stems of flowering plants.
D) The hydroxyl groups of neighboring cellulose molecules interact to form strong, insoluble
fibers.
E) It is a branched polymer of glucose.
Answer: E
Page Ref: Section 3
1

4) When Keq of a reaction = 1, then
A) the forward reaction is faster than the reverse reaction.
B) the reverse reaction is faster than the forward reaction.
C) the forward and reverse reaction rate constants are equal.
D) more products are formed than reactants.
E) fewer products are formed than reactants.
Answer: C
Page Ref: Section 4
5) Which statement is true about a reaction with an equilibrium constant, Keq, equal to 1000?
A) The forward rate constant is 1000 times greater than the reverse rate constant.
B) The forward rate constant is 3 times greater than reverse rate constant.
C) The forward rate constant is 1000 times smaller than the reverse rate constant.
D) The forward rate constant is 3 times smaller than the reverse rate constant.
E) There is not enough information given to compare the forward and reverse rate constants.
Answer: A
Page Ref: Section 4
6) The study of the energy changes during metabolic reactions is called ________.
A) bioinformatics
B) metabodynamics
C) thermometrics
D) bioenergetics
E) biological heat dynamics
Answer: D
Page Ref: Section 4
7) A spontaneous chemical reaction always has a ________ change.
A) positive Gibbʹs free energy
B) negative Gibbʹs free energy
C) positive enthalpy
D) negative enthalpy
E) positive entropy
Answer: B
Page Ref: Section 4
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8) Prokaryotes are valuable tools for biochemists because
A) E. coli is well-studied and typical of prokaryotes.
B) they contain as many genes as eukaryotic cells.
C) many of their chromosomes are sequenced.
D) they are not very diverse organisms.
E) All of the above
Answer: C
Page Ref: Section 6
9) Which cellular component carries out oxidation reactions, some of which produce hydrogen
peroxide?
A) peroxisomes
B) mitochondria
C) chloroplasts
D) lysosomes
E) vacuoles
Answer: A
Page Ref: Section 8
10) Why is it important that the enzymes in lysosomes are more active at acidic pH than at neutral
pH?
A) Since lysosomes are primarily found in the stomach acid of mammals, their pH
dependence allows for maximum efficiency for the digestion of foodstuffs.
B) It prevents their diffusion out of the lysosomes.
C) It maximizes the interaction with their substrates which are always bases.
D) It prevents them from accidentally degrading the macromolecules in the cytosol.
E) It allows for regulation of their uptake by the mitochondria.
Answer: D
Page Ref: Section 8
11) Molecules from living cells cannot be synthesized outside of living cells.
Answer: FALSE
Page Ref: Section 1
12) Fermentation in the absence of cells demonstrated that metabolic processes were chemical in
nature.
Answer: TRUE
Page Ref: Section 1
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13) Enzymes are protein catalysts that form an intermediate with a substrate that fits into it.
Answer: TRUE
Page Ref: Section 1
14) The modified lock-and-key theory of enzyme action proposed by Emil Fischer has been
completely replaced by more modern ideas of catalysis.
Answer: FALSE
Page Ref: Section 1
15) Enzymes are not as efficient as most catalysts used in organic chemistry, since they must
function at body temperature.
Answer: FALSE
Page Ref: Section 1
16) Bioinformatics has permitted rapid advances in our understanding of structural
macromolecules from living cells.
Answer: TRUE
Page Ref: Section 1
17) The role of DNA as the genetic material was confirmed by transforming Streptococci in
experiments performed several years after the famous Watson and Crick description of DNA
structure.
Answer: FALSE
Page Ref: Section 1
18) Crick referred to the flow of information from nucleic acid to protein as the Central Dogma.
Answer: TRUE
Page Ref: Section 1
19) Functional groups describe one or more portions of organic compounds found in living cells.
Answer: TRUE
Page Ref: Section 2
20) A phosphate ester contains a phosphate functional group.
Answer: TRUE
Page Ref: Section 2
21) Under most biological conditions, acid groups and amino groups are fully protonated.
Answer: FALSE
Page Ref: Section 2
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22) Removal of water from residues of a macromolecule results in the formation of that
macromolecule.
Answer: TRUE
Page Ref: Section 3
23) Mr is the mass of a molecule relative to 1/12 the mass of an atom of the most common isotope of
carbon.
Answer: TRUE
Page Ref: Section 3
24) Biochemists describing the molecular weight of a protein really mean the atomic weight in
grams.
Answer: FALSE
Page Ref: Section 3
25) The absolute molecular mass of macromolecules is given in daltons, where 1 dalton = 1 atomic
mass unit.
Answer: TRUE
Page Ref: Section 3
26) A peptide bond is formed by the condensation of different functional groups from two amino
acids.
Answer: TRUE
Page Ref: Section 3
27) The conformation of a protein enzyme determines whether it is functional or not.
Answer: TRUE
Page Ref: Section 3
28) Lysozyme is an enzyme with a cleft or depression at its active site.
Answer: TRUE
Page Ref: Section 3
29) The Haworth projection of the ring form of a monosaccharide always shows a flat plane with
one edge projecting out of the page (using thicker lines).
Answer: TRUE
Page Ref: Section 3
30) Sugars with six carbons are the only ones capable of forming a ring structure as shown in a
Haworth projection.
Answer: FALSE
Page Ref: Section 3
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31) ATP contains both phosphoester and phosphoanhydride linkages.
Answer: TRUE
Page Ref: Section 3
32) A phosphodiester linkage in DNA contains two phosphorous atoms.
Answer: FALSE
Page Ref: Section 3
33) Lipids aggregate to form bilayers because some lipid molecules are hydrophobic and other
lipid molecules are hydrophilic.
Answer: FALSE
Page Ref: Section 3
34) Thermodynamics and its laws are obeyed by living cells.
Answer: TRUE
Page Ref: Section 4
35) The tendency of a metabolic reaction to proceed is due to the free energy of both the reactants
and products as well as the change in randomness of that reaction.
Answer: TRUE
Page Ref: Section 4
36) Biochemical reactions are more likely to proceed if the reaction has an increase in enthalpy (
△H) and a decrease in entropy (△S).
Answer: FALSE
Page Ref: Section 4
37) All prokaryotic cells are about 1/10 the size of an average eukaryotic cell or smaller.
Answer: FALSE
Page Ref: Section 5
38) All cells have kept the same general patterns of metabolism, a very similar genetic code and the
same monomers or residues.
Answer: TRUE
Page Ref: Section 5
39) Eukaryotes include plants, animals and bacteria.
Answer: FALSE
Page Ref: Section 5
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40) The only reason phages are not considered to be cells is because they do not contain a plasma
membrane.
Answer: FALSE
Page Ref: Section 6
41) Diffusion is an adequate means of distributing nutrients in prokaryotic cytoplasm because they
have more surface area than volume compared to most eukaryotes.
Answer: TRUE
Page Ref: Section 7
42) Eukaryotic cells are distinguished from prokaryotes by their usually larger size, a complex
cytoskeleton and membrane-bounded organelles.
Answer: TRUE
Page Ref: Section 7
43) Chloroplasts are organelles found in plants, algae and some protists and are the site of
photosynthesis.
Answer: TRUE
Page Ref: Section 7
44) The endoplasmic reticulum is the major site of RNA synthesis and the site of assembly of
ribosomes.
Answer: FALSE
Page Ref: Section 8
45) The nuclear envelope is a membrane that surrounds the nucleus and is continuous with the
endoplasmic reticulum.
Answer: TRUE
Page Ref: Section 8
46) Ribosomes on the surface of rough endoplasmic reticulum are the site of ATP synthesis.
Answer: FALSE
Page Ref: Section 8
47) The Golgi apparatus consists of flattened, fluid-filled, membranous sacs and is responsible for
chemical modification and sorting of some biomolecules.
Answer: TRUE
Page Ref: Section 8
48) Mitochondria are the main sites of energy transduction in aerobic eukaryotic cells.
Answer: TRUE
Page Ref: Section 8
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49) The mitochondria and Golgi apparatus are two organelles which originated from bacteria and
were incorporated into eukaryotic cells via symbiosis.
Answer: FALSE
Page Ref: Section 8
50) In an animal cell, DNA can be found only in the nucleus.
Answer: FALSE
Page Ref: Section 8
51) Actin has been shown to be one of the most evolutionarily conserved proteins. It is present in
all eukaryotic cells and frequently is the most abundant protein in the cell.
Answer: TRUE
Page Ref: Section 8
52) The mitotic spindles are formed from microtubule proteins.
Answer: TRUE
Page Ref: Section 8
53) The filament fibers in the cytoskeleton are composed primarily of carbohydrate molecules.
Answer: FALSE
Page Ref: Section 8
54) The diffusion of large molecules such as enzymes is significantly slowed by the presence of the
cytoskeleton.
Answer: TRUE
Page Ref: Section 8
55) In eukaryotic cells lysosomes are specialized digestive vesicles with a highly acidic interior.
Answer: TRUE
Page Ref: Section 8
56) The process of cell division that occurs in the tissues is called mitosis.
Answer: TRUE
Page Ref: Section 8
57) Photosynthesis involves capturing energy from light that is then used to drive the formation of
carbohydrates from carbon dioxide and water.
Answer: TRUE
Page Ref: Section 8
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Chapter 2 Water
1) Which is not a proper way to form a hydrogen bond? (The symbol ʺRʺ represents a general
organic group. The hydrogen bonding is represented by dashed lines.)
A) I B) II C) III D) IV
Answer: B
Page Ref: Section 1
2) Which statement does not explain the polarity of water?
A) Oxygen is more electronegative than hydrogen.
B) Water molecules have a bent geometry (V-shaped).
C) The oxygen in water has sp2 hybrid orbitals.
D) In water the hydrogen carries a partial positive charge (δ+).
Answer: C
Page Ref: Section 1
3) Which substance do you expect to be most soluble in water?
A) ammonia, NH3 B) methane, CH4
C) carbon dioxide, CO2 D) nitrogen, N2
Answer: A
Page Ref: Section 1
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4) What is the maximum number of hydrogen bonds that one water molecule can have with
neighboring water molecules?
A) 1 B) 2 C) 3 D) 4
Answer: D
Page Ref: Section 2
5) The abundance of water in the cells and tissues helps to minimize temperature fluctuations.
This is due to what property of water?
A) density B) viscosity C) specific heat D) boiling point
Answer: C
Page Ref: Section 2
6) Compounds that ionize when dissolved in water are called ________.
A) electrolytes B) polar compounds
C) hydrophobic compounds D) amphipathic compounds
Answer: A
Page Ref: Section 3
7) Electrolytes dissolve readily in water because
A) they are held together by electrostatic forces.
B) they are hydrophobic.
C) water molecules can cluster about cations.
D) water molecules can cluster about anions.
E) water molecules can cluster about cations and anions.
Answer: E
Page Ref: Section 3
8) A molecule or ion is said to be hydrated when it ________.
A) is neutralized by water
B) is surrounded by water molecules
C) reacts and forms a covalent bond to water
D) aggregates with other molecules or ions to form a micelle in water
Answer: B
Page Ref: Section 3
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9) Which would you expect to be most soluble in water?
A) I B) II C) III D) IV
Answer: A
Page Ref: Section 3
10) Solutes diffuse more slowly in cytoplasm than in water because of
A) the higher viscosity of water.
B) the higher heat of vaporization of water.
C) the presence of many crowded molecules in the cytoplasm.
D) the absence of charged molecules inside cells.
Answer: C
Page Ref: Section 3
11) The ________ pressure is the pressure required to prevent the flow of solvent through a
solvent-permeable membrane that separates two solutions of different solute concentration.
A) hydrostatic B) electromotive C) osmotic D) partial
Answer: C
Page Ref: Section 3
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12) Which is true about the solubility of electrolytes in water?
A) They are all insoluble in water.
B) They are usually only sparingly soluble in water.
C) They often form super-saturated aqueous solutions.
D) They readily dissolve and ionize in water.
Answer: D
Page Ref: Section 3
13) What is the difference between a particle being hydrated versus being solvated?
A) A hydrated particle is surrounded by a shell of water. A solvated molecule is surrounded
by a shell of solvent molecules, not necessarily water.
B) The terms hydrated and solvated mean exactly the same thing.
C) A hydrated particle has reacted with hydrogen. A solvated particle is dissolved in a
solvent.
D) The word hydrated is used only when the solute is an electrolyte.
Answer: A
Page Ref: Section 3
14) The osmotic pressure of an aqueous solution depends on
A) the chemical nature of the solute.
B) the molar concentration of solute.
C) the hydrophobic effect of the solute.
D) All of the above.
E) None of the above.
Answer: B
Page Ref: Section 3
15) The osmotic pressure of a 0.010 M sucrose (C12H22O11) solution at 25 °C is 0.24 atm. How does
the osmotic pressure of a 0.010 M glucose (C6H12O6) solution at 25 °C compare to this? Note
that neither solute is volatile or ionizable.
A) The glucose solution has a lower osmotic pressure because its molar mass is lower than
sucrose.
B) The glucose solution has a higher osmotic pressure because its molar mass is lower than
sucrose.
C) The osmotic pressures are equal because the solutions have the same molar concentration.
D) Nothing can be said about the osmotic pressure of the glucose solution without more
information.
Answer: C
Page Ref: Section 3
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16) Oil and water do not form a solution due to ________.
A) the hydrophobic effect
B) the inability of oil to hydrogen bond with water
C) the nonpolarity of oil
D) All of the above (A-C)
E) A and C only
Answer: D
Page Ref: Section 4
17) Molecules that are both hydrophobic and hydrophilic are ________.
A) amphipathic B) amphoteric C) bipolar D) not possible
Answer: A
Page Ref: Section 4
18) Which molecule or ion below is amphipathic?
A) H2NCH2COOH (glycine) B) H2O
C) CH3(CH2)14COO- D) CH3CH2CH2CH2CH3
Answer: C
Page Ref: Section 4
19) Which statement explains the cleaning action of soap on greasy dishes?
A) The soap changes the water-solubility of the grease so that it is easily dissolved by the
water.
B) The grease is trapped inside the hydrophobic interior of micelles made of soap molecules.
C) The soap chemically breaks down the grease into smaller, more water-soluble molecules.
D) The soap hydrates the grease with its polar head groups and holds it in suspension.
Answer: B
Page Ref: Section 4
20) Some ions such as thiocyanate that are poorly solvated in water and can enhance the solubility
of nonpolar compounds in water by disordering the water molecules are called ________.
A) azeotropes B) hydrophobic ions
C) zeolytes D) chaotropes
Answer: D
Page Ref: Section 4
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21) Which of the following is NOT a ʺweakʺ interaction?
A) hydrogen bonds
B) van der Waals forces
C) disulfide bonds
D) ionic interactions
E) hydrophobic interactions
Answer: C
Page Ref: Section 5
22) Which of the following weak interactions is not an electrostatic interaction?
A) hydrogen bonds B) charge-charge interactions
C) hydrophobic interactions D) van der Waals forces
Answer: C
Page Ref: Section 5
23) Which of these noncovalent forces in biological systems is usually the strongest?
A) hydrogen bonds B) London dispersion forces
C) hydrophobic interactions D) van der Waals forces
Answer: A
Page Ref: Section 5
24) Hydrogen bonds can occur when hydrogen is covalently bonded to atoms like nitrogen and
oxygen. What property of nitrogen and oxygen is important for this?
A) atomic mass B) ionizability
C) hydrophobicity D) electronegativity
Answer: D
Page Ref: Section 5
25) Attractions of oppositely charged functional groups of proteins are sometimes called ________.
A) salt bridges or ion pairing B) disulfide bridges
C) London bridges D) hydrophilic bridges
Answer: A
Page Ref: Section 5
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26) Which is true about hydrogen bonding for biological molecules?
A) Hydrogen bonds are strong enough to confer structural stability, for example in DNA.
B) Hydrogen bonds are weak enough to be easily broken (weaker than covalent bonds).
C) They contribute to the water solubility of many macromolecules.
D) All of the above
Answer: D
Page Ref: Section 5
27) London dispersion forces are attractive forces that arise due to
A) infinitesimal dipoles generated by the constant random motion of electrons.
B) permanent dipoles of molecules containing covalent bonds between atoms of very
different electronegativities.
C) the hydrophobic effect.
D) ion pairing between oppositely charged functional groups.
Answer: A
Page Ref: Section 5
28) The aggregation of nonpolar molecules or groups in water is thermodynamically due to the
A) increased entropy of the nonpolar molecules when they associate.
B) decreased enthalpy of the system.
C) increased entropy of the water molecules.
D) very strong van der Waals forces among the nonpolar molecules or groups.
Answer: C
Page Ref: Section 5
29) Water clustered about nonpolar molecules contribute to hydrophobic interactions because
A) Their number is minimized to increase the total entropy of water.
B) Nonpolar molecules are more highly organized than polar molecules.
C) Water molecules in the cell are more organized in the regions away from the nonpolar
molecule.
D) All of the above
E) B and C
Answer: A
Page Ref: Section 5
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30) The three dimensional structure of most proteins is largely determined by
A) other proteins which fold them.
B) weak noncovalent interactions.
C) denaturation.
D) hydrogen bonds.
E) All of the above
Answer: B
Page Ref: Section 5
31) The oxygen atom of water is nucleophilic because
A) it has a negative oxidation number.
B) it carries a partial positive charge.
C) it has two unshared pair of electrons.
D) it seeks electron-rich molecules.
E) All of the above
Answer: C
Page Ref: Section 6
32) Water is a nucleophile, yet it does not usually hydrolyze macromolecules in cells because
A) covalent bonds linking macromolecule subunits are stable at cell pH.
B) covalent bonds linking macromolecule subunits are stable at cell temperature.
C) the concentration of water is much too small in cells.
D) A and B
Answer: D
Page Ref: Section 6
33) Enzymes which condense subunits of macromolecules during their synthesis usually
A) transfer an acyl or carbonyl group to an electrophile.
B) exclude water from the active site.
C) contain inhibitors of hydrolases.
D) are catalyzing thermodynamically favored reactions.
E) All of the above
Answer: B
Page Ref: Section 6
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34) The ion-product constant for water, Kw, is
A) 1 x 10-7 M2. B) 1 x 10-7 M. C) 1 x 10-14 M2. D) 1 x 10-14 M.
Answer: C
Page Ref: Section 7
35) In pure water hydronium ions are formed by ________ attack of oxygen on a proton in an
adjacent water molecule.
A) ionic B) nucleophilic C) electrophilic D) covalent
Answer: B
Page Ref: Section 7
36) Pure water has a concentration of
A) 18 g/ml. B) 1 g/ml. C) 1000 g/ml. D) 55 M.
Answer: D
Page Ref: Section 7
37) Which statement best characterizes the distribution of charge in the hydronium ion, H3O+?
A) The positive charge is distributed over all of the atoms in the ion.
B) The positive charge is localized only on the oxygen atom.
C) The positive charge is distributed between the three hydrogen atoms only.
D) The positive charge is localized on only one of the hydrogen atoms.
Answer: A
Page Ref: Section 7
38) Which statement below is true about the relative lifetime of a hydrogen bond, compared to the
rate of waterʹs ionization to hydroxide ions and hydronium ions?
A) The strength of hydrogen bonding makes its dissociation much slower than the
ionization of water.
B) The rate of dissociation of a hydrogen bond is the same order of magnitude as the rate of
ionization of water.
C) The two rates are linked in such a way that the more the water is ionized, the stronger
and longer lasting hydrogen bonding will be.
D) The lifetime of a water molecule before it is ionized is about 109 greater than the lifetime
of a hydrogen bond.
Answer: D
Page Ref: Section 7
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39) The self-ionization of water is ________.
A) a unimolecular dissociation of a single water molecule to H+ and OH-
B) a biomolecular reaction between two water molecules to yield H3O+ and OH-
C) a result of hydrophobic interactions
D) a termolecular reaction involving the simultaneous collision of H2O, H+ and OH-
Answer: B
Page Ref: Section 7
40) How does the ion-product of water, Kw, relate to the equilibrium constant, Keq, for the
dissociation reaction of water?
A) Kw is found by multiplying Keq by the concentration of water.
B) Kw just another symbol for Keq , so they are equal.
C) Kw is found by dividing Keq by the ideal gas constant.
D) Kw is found by multiplying Keq by the concentrations of hydronium ion and hydroxide
ion.
Answer: A
Page Ref: Section 7
41) A solution containing 10-8 M HCl and 10-8 M acetic acid contains H+ which is supplied mostly
by
A) the strong acid.
B) the weak acid.
C) both the strong and the weak acids.
D) water.
E) All of the above
Answer: D
Page Ref: Section 8
42) Basic solutions form when chemicals are dissolved in water and remove
A) OH-.
B) H+.
C) Na+.
D) A and B
E) A, B and C
Answer: B
Page Ref: Section 8
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43) The pH of a 10-4 M solution of HCl is
A) 3.
B) 3.5.
C) 4.
D) 4.5.
E) greater than 4.5.
Answer: C
Page Ref: Section 8
44) Compare solution A with pH = 4 to solution B with pH = 6.
A) The concentration of hydronium ion in solution A is twice that in solution B.
B) Solution A has greater buffering capacity than solution B.
C) The concentration of hydronium ion in solution A is 100 times that in solution B.
D) The hydroxide concentrations are equal in the two solutions since pH only measures the
concentration of H+.
Answer: C
Page Ref: Section 8
45) If human blood is not maintained at close to pH = 7.4, a person can develop
A) acidosis.
B) alkalosis.
C) diabetes.
D) Both A and B
E) None of the above
Answer: D
Page Ref: Section 8
46) The Henderson-Hasselbalch equation can be used to calculate
A) the pH of a solution of an organic acid.
B) the amount of salt and acid to add to form a specific buffer.
C) the pKa of a weak acid.
D) All of the above
E) A and C only
Answer: D
Page Ref: Section 9
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47) The ratio of the concentration of a ________ over ________ describes the proportions of forms of
a weak acid necessary to satisfy the Henderson-Hasselbalch equation.
A) conjugate acid; conjugate base
B) conjugate base; conjugate acid
C) proton donor; proton acceptor
D) proton acceptor; proton donor
E) B and D
Answer: E
Page Ref: Section 9
48) At the midpoint of a titration curve
A) the concentration of a conjugate base is equal to the concentration of a conjugate acid
B) the pH equals the pKa
C) the ability of the solution to buffer is best
D) All of the above
E) A and B only
Answer: D
Page Ref: Section 9
49) Histidine contains an imidazole group which is titratable. A histidine buffer can be prepared
using
A) NaOH and histidine.
B) NaOH and imidazolium ion.
C) imidazolium ion and imidazole (conjugate base).
D) HCl and imidazole.
E) All of the above
Answer: E
Page Ref: Section 9
50) The imidazolium ion has a pKa = 7.0. Imidazolium buffers can be prepared for pH values of
A) 6.5 to 7.5. B) 6.1 to 7.1. C) 5.5 to 8.5. D) 6.0 to 8.0. E) 6.0 to 7.5.
Answer: D
Page Ref: Section 9
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51) Since HCl is a strong acid its value of Ka is ________.
A) effectively equal to infinity B) equal to Kw
C) zero D) dependent on the concentration of HCl
Answer: A
Page Ref: Section 9
52) For a weak acid with a pKa = 6.5, the effective buffering range is usually considered to be
A) pH 6 to pH 7.
B) pH 6.4 to pH 6.6.
C) pH 5.5 to pH 7.5.
D) dependent on the molarity of the acid.
E) B and C
Answer: C
Page Ref: Section 10
53) Blood pH is primarily regulated by
A) a protein buffer system.
B) the carbon dioxide - carbonic acid - bicarbonate buffer system.
C) the phosphate buffering system.
D) carbonic acid (H2CO3).
E) B and C
Answer: B
Page Ref: Section 10
54) Intracellular buffers include
A) proteins.
B) inorganic phosphate.
C) hemoglobin.
D) Both A and B
E) A, B and C
Answer: D
Page Ref: Section 10
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55) pKa values of phosphoric acid are 2.2, 7.2 and 12.7. A phosphate buffer of pH = 7.4 can be
prepared using
A) H2PO4- and HPO42-. B) HPO42- and PO43-.
C) H3PO4 and HCl. D) None of the above
Answer: A
Page Ref: Section 10
56) Acetic acid has a pKa of 4.8. How many milliliters of 0.2 M acetic acid and 0.1 M sodium acetate
are required to prepare 1 liter of 0.1 M buffer solution having a pH of 4.8?
A) 500 ml acetic acid and 500 ml sodium acetate
B) 250 ml acetic acid and 250 ml sodium acetate, then 500 ml water
C) 250 ml acetic acid and 500 ml sodium acetate, then 250 ml water
D) 500 ml acetic acid and 250 ml sodium acetate, then 250 ml water
Answer: B
Page Ref: Section 10
57) The pH of human blood is maintained at 7.4 by
A) buffering proteins.
B) carbon dioxide-carbonic acid buffer systems.
C) a bicarbonate buffer system.
D) B and C
E) A, B and C
Answer: D
Page Ref: Section 10
58) The solubility rule ʺlike dissolves likeʺ refers primarily to similarities in amphipathic nature
between the solute and solvent.
Answer: FALSE
Page Ref: Section 1
59) The hydrogen bonding between water molecules in ice gives water an unusually low melting
point compared to other molecules of similar size and molecular weight that cannot form
hydrogen bonds.
Answer: FALSE
Page Ref: Section 2
60) The water solubility of alcohols with a single hydroxyl group increases as a function of
molecular weight.
Answer: FALSE
Page Ref: Section 3
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61) A hydrated potassium ion is surrounded by a shell of water molecules oriented primarily with
their oxygen atoms toward the potassium ion.
Answer: TRUE
Page Ref: Section 3
62) In the detergent, sodium dodecyl sulfate, the sulfate groups are very hydrophobic.
Answer: FALSE
Page Ref: Section 4
63) Van der Waals forces are very strongly repulsive at short nuclear distances and very weak at
long internuclear distances.
Answer: TRUE
Page Ref: Section 5
64) The combined effect of many weak noncovalent interactions can be very significant in
determining factors such as three-dimensional structure for large biological molecules.
Answer: TRUE
Page Ref: Section 5
65) Water molecules that surround a less polar molecule in solution are immobile and ordered.
Answer: TRUE
Page Ref: Section 5
66) The strength of van der Waals forces between two molecules changes as the distance between
them changes.
Answer: TRUE
Page Ref: Section 5
67) The attractive force between two atoms is maximized when they are separated by the sum of
their van der Waals radii.
Answer: TRUE
Page Ref: Section 5
68) Salt bridges are often found on the surfaces of proteins where they are stabilized by water.
Answer: FALSE
Page Ref: Section 5
69) Hydrogen bonds in the interior of a protein or other macromolecule are stronger than those on
the exterior.
Answer: FALSE
Page Ref: Section 5
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70) Micelles are stabilized in water by interactions of nonpolar molecules with each other.
Answer: TRUE
Page Ref: Section 5
71) Hydrophobic interactions are sometimes called ʺbondsʺ, because each one is as strong as a
covalent bond.
Answer: FALSE
Page Ref: Section 5
72) Proteins dissolved in water can be hydrolyzed by nucleophilic attack from the water molecules.
Answer: TRUE
Page Ref: Section 6
73) An intermediate formed by the enzyme glutamine synthetase, gamma-glutamyl phosphate, is
rapidly hydrolyzed by water if the enzyme is not around to protect it.
Answer: TRUE
Page Ref: Section 6
74) When acid is added to pure water, Kw, the ion-product constant of water, changes.
Answer: FALSE
Page Ref: Section 7
75) The equilibrium constant of water (Keq) is the rate that dissociation of the molecule occurs at
room temperature.
Answer: FALSE
Page Ref: Section 7
76) The H+ (or H3O+) in cells is the same concentration as that of undissociated water.
Answer: FALSE
Page Ref: Section 8
77) Hyperventilation can result in alkalosis because there is excessive loss of carbon dioxide and,
therefore a loss of carbonic acid.
Answer: TRUE
Page Ref: Section 8
78) Since the pKa of acetic acid is 4.8, it can be used to prepare a buffer to maintain physiological
pH.
Answer: FALSE
Page Ref: Section 9
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Chapter 3 Amino Acids and the Primary Structures
of Proteins
1) Amino acids are named that because each one
A) is a unique carboxylic acid.
B) has a standard configuration.
C) is a carboxyl derivative of an amide acid.
D) is an amino derivative of a carboxylic acid.
Answer: D
Page Ref: Section 1
2) Amino acids found in meteorites and near stars are
A) D isomers only. B) L isomers only.
C) Both D and L isomers. D) not isomers.
Answer: C
Page Ref: Section 1
3) The last common ancestor of modern organisms must have used
A) both D and L amino acids. B) D amino acids.
C) L amino acids. D) either D or L amino acids.
Answer: C
Page Ref: Section 1
4) If the R group of an amino acid is -CH3, then the name of this compound is
A) methyl amino acid.
B) 2-aminopropanoic acid.
C) alanine.
D) All of the above
E) B and C
Answer: E
Page Ref: Section 1
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5) Amino acids with non-ionizable side chains are zwitterions when they are ________.
A) in any solution
B) at physiological pH, pH = 7.4
C) in acidic solutions only
D) in alkaline solutions only
E) All of the above
Answer: B
Page Ref: Section 1
6) Glycine is not a stereoisomer because
A) it has no chiral carbon.
B) it does not form enantiomers.
C) it does not exist in two non-superimposable mirror-image forms.
D) All of the above
E) A and B only
Answer: D
Page Ref: Section 1
7) An amino acid with two chiral carbon atoms
A) is unstable.
B) can exist in 4 forms all of which are superimposable.
C) can form three possible stereoisomers.
D) can form four possible stereoisomers.
E) can form five possible stereoisomers.
Answer: D
Page Ref: Section 1
8) The RS system of nomenclature describes
A) amino acids not easily described by the DL system.
B) the way the R groups are arranged.
C) the chiral carbon centers of amino acids.
D) the strength of the chemical groups in amino acids.
Answer: C
Page Ref: Section 1
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9) The R group of an amino acid determines if it is
A) hyrophilic or hydrophobic.
B) polar or nonpolar.
C) charged or uncharged.
D) an acid or a base.
E) All of the above
Answer: E
Page Ref: Section 1
10) Proline is distinct among the 20 commonly found amino acids because
A) it is a ring compound.
B) it is hydrophilic and ionic.
C) the nitrogen of the amino group is in a ring.
D) the carbon of the carboxyl group is in a ring.
E) it has little effect on protein structure.
Answer: C
Page Ref: Section 2
11) Tyrosine and tryptophan are less hydrophobic than phenylalanine because
A) phenylalanine has an indole group.
B) phenylalanine has no polar group in the side chain.
C) phenylalanine is a phenol.
D) tyrosine and tryptophan have smaller R groups.
E) All of the above
Answer: B
Page Ref: Section 2
12) Ultraviolet (UV) light can be used to estimate protein solution concentrations because
A) phenylalanine absorbs at 260 nm.
B) all the amino acids absorb UV light.
C) aromatic amino acids absorb at 280 nm.
D) tryptophan and tyrosine absorb at 280 nm.
E) All of the above
Answer: D
Page Ref: Section 2
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Test Bank For Principles Of Biochemistry, 4th Edition

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