Test Bank For Biochemistry: Concepts and Connections, 1st Edition

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1Biochemistry: Concepts and Connections(Appling et al.)Chapter 1Biochemistry and the Language of Chemistry1) The water content in the human body is approximately:A) 90%.B) 80%.C) 70%.D) 60%.E) 50%.Answer: C2) The four most abundant chemical elements in living systems are:A) hydrogen, oxygen, sulfur and phosphorus.B) hydrogen, carbon, nitrogen and oxygen.C) sodium, potassium, carbon and oxygen.D) sodium, potassium, nitrogen and sulfur.E) carbon, nitrogen, oxygen and potassium.Answer: BObjective: 1.23) Nearly all proteins contain:A) cobalt.B) phosphorus.C) selenium.D) sulfur.E) none of the above.Answer: DObjective: 1.2Global LO: G74) Which of the following statements is FALSE?A) Proteins can be structural components of cells.B) Proteins can transmit signals between cells.C) Proteins can transport molecules within cells and between cells.D) Proteins can be both hormones and hormone receptors.E) Proteins are the only biological polymer that can catalyze biochemical reactions.Answer: EObjective: 1.2Global LO: G7

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25) Which of the following is NOT classed as a lipid?A) CholesterolB) Palmitic acidC) GlycerolD) Phosphatidyl serineE) TriacylglycerolAnswer: CObjective: 1.2Global LO: G76) Amino acids and simple organic compounds like carbon dioxide and hydrogen cyanide cannotbe produced without the use of enzymes.Answer: FALSEObjective: 1.2Global LO: G77) Oxidation-reduction reactions, which are the basis of many biochemical reactions andpathways, cannot take place in the absence of oxygen.Answer: FALSEObjective: 1.2Global LO: G78) Many biochemical reactions that form biopolymers from monomeric units involve theremoval of water.Answer: TRUEObjective: 1.2Global LO: G79) The principle component of a biological membrane is a triglyceride.Answer: FALSEObjective: 1.2Global LO: G710) The chemical element ________ has a role in both transfer of energy as well as in thestructure of nucleic acids.Answer: phosphorusObjective: 1.2Global LO: G711) List the four major classes of biological macromolecules.Answer: lipids, carbohydrates, proteins, nucleic acidsObjective: 1.2Global LO: G7

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312) An amphipathic molecule provides the foundation for biological membranes because theyhave both ________ and ________ functional groups.Answer: hydrophobic, hydrophilicObjective: 1.2Global LO: G713) Genomics is concerned with the entire ________, while ________ is focused on identifyingall of the proteins of a cell.Answer: genome, proteomicsObjective: 1.5Global LO: G1

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1Biochemistry: Concepts and Connections(Appling et al.)Chapter 2The Chemical Foundation of Life: Weak Interactions in an AqueousEnvironment1) Each of the following is a noncovalent interaction EXCEPT:A) a hydrogen bond.B) a carbon-hydrogen bond.C) the interaction between an amino and acarboxylate group.D) a van der Waals interaction.E) an interaction between—NH3+and a water molecule.Answer: BObjective: 2.1Global LO: G72) The most important noncovalent interaction in biochemistry is the ________ bond.Answer: hydrogenObjective: 2.1Global LO: G73) Which of the following is FALSE when considering van der Waals interactions?A) The van der Waals radius represents the most stable distance between two interacting centers.B) Van der Waals radii can determine molecular surfaces.C) Molecules that interact by van der Waals forces do not interpenetrate.D) The total interaction energy is the sum of the attractive and repulsive forces.E) They are not important in determining the stability of three-dimensional structures of proteins.Answer: EObjective: 2.2Global LO: G24) Which of the following in biological compounds are sufficiently electronegative to serve asstrong donors in a hydrogen bond?A) Hydrogen and oxygenB) Oxygen and nitrogenC) Nitrogen and hydrogenD) Hydrogen and carbonE) Nitrogen and carbonAnswer: BObjective: 2.2Global LO: G75) Hydrogen bonds share features of both covalent and noncovalent bonds.Answer: TRUEObjective: 2.2Global LO: G2

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26) Which of the following is TRUE of hydrophobic molecules?A) They have limited solubility in water.B) Water forms a cage-like structure around them.C) Dissolving in water decreases the entropy of the mixture.D) They self-associate by releasing some of the surrounding water molecules.E) All of the aboveAnswer: EObjective: 2.3Global LO: G27) Water is both a hydrogen bond donor and acceptor.Answer: TRUEObjective: 2.3Global LO: G28) Amphipathic molecules are not able to interact via van der Waals forces.Answer: FALSEObjective: 2.3Global LO: G29) Ionic compounds can be readily dissolved in water because the high dielectric constant ofwater screens and decreases the ________ force between the oppositely charged ions.Answer: electrostaticObjective: 2.3Global LO: G710) The ________ describes the tendency for hydrophobic molecules to aggregate because of theexclusion of water with the consequent increase of entropy of the solvent.Answer: hydrophobic effectObjective: 2.3Global LO: G711) Glycine cannot serve as a buffer because it has two ionizable groups.Answer: FALSEObjective: 2.4Global LO: G712) The average charge on an amino acid below its pI will be positive.Answer: TRUEObjective: 2.4Global LO: G213) Calculate the acid dissociation constantKaof a 0.2 M solution of weak acid that is 0.1%ionized.Answer: 2 × 10-7Objective: 2.4Global LO: G4

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314) Calculate the pH of a 0.1 M phosphate buffer (pKa = 6.86) that contains equal amounts ofacid and conjugate base.Answer: 6.86Objective: 2.4Global LO: G415) Calculate the pH of a 0.2 M acetate buffer (pKa = 4.77) that contains twice as much acid asconjugate base.Answer: 4.47Objective: 2.4Global LO: G416) The pKaof each amino acid residue in a protein will not be influenced by the adjacentresidue.Answer: FALSEObjective: 2.5Global LO: G217) Calculatethe pH at the end of an enzyme-catalyzed reaction if it were carried out in a 0.1 Mphosphate buffer, pH 6.86 and 0.005 M of acid was produced during the reaction?Answer: 6.77Objective: 2.5Global LO: G418) If hydroxide is added to an amino acid it will become increasingly ________ charged.Answer: negativelyObjective: 2.6Global LO: G719) Calculate the pH of a weak acid that is 0.2% ionized in a 0.2 M solution.Answer: 3.39Objective: 2.6Global LO: G420) The net charge on an amino acid at its isoelectric point (pI) is ________.Answer: zeroObjective: 2.7Global LO: G7

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421) Many proteins interact with DNA at physiological pH because:A) proteins are naturally attracted to DNA regardless of the pH.B) the negatively charged DNA is electrostatically attracted to positively charged regions onproteins.C) the positively charged DNA is electrostatically attracted to negatively charged regions onproteins.D) proteins and DNA interact using mainly hydrophobic interactions.E) both proteins and DNA are at their isoelectric points at physiological pH and tend toaggregate.Answer: BObjective: 2.8Global LO: G222) Small ions in biological fluids:A) encourage strong electrostatic interactions between oppositely charged macroions at low ionicstrengths.B) encourage strong electrostatic interactions between oppositely charged macroions at highionic strengths.C) have no effect on the interactions between oppositely charged macroions.D) tend to cluster around macroions of the same charge.E) have large effects on pH.Answer: AObjective: 2.8Global LO: G7

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1Biochemistry: Concepts and Connections(Appling et al.)Chapter 3The Energetics of Life1) Which of the following statements is FALSE?A) Organisms are open systems as they can exchange both energy and materials with theirenvironments.B) In an open system energy can be converted from one form into another.C) Organisms are open systems as they can create energy from their environments.D) Energy can be transferred between a system and the surroundings.E) In biochemical processes, energy can neither be created or destroyed.Answer: CObjective: 3.1Global LO: G72) Which of the following statements is FALSE?A) Entropy is a measure of disorder.B) The entropy of an isolated system will tend to increase to a maximum value.C) Biological systems are highly ordered so entropy changes are not relevant.D) Biological systems expend energy to overcome entropy.E) The entropy of a biological system can decrease.Answer: CObjective: 3.2Global LO: G23) A biochemical reaction will proceed in the direction as written if:A)△G= zero.B)△G> 0.C)△G< 0.D)△H> 0.E)△H< 0.Answer: CObjective: 3.2Global LO: G24) Life is an irreversible process, such that it never comes to equilibrium.Answer: TRUEObjective: 3.2Global LO: G2

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25) The equilibrium constant of a reaction:A) is not related to the change in free energy of the reaction.B) is the same as the mass action ratio when the reaction is displaced from equilibrium.C) can change if the concentration of reactants and products are changed.D) is related to the change in free energy of the reaction.E) cannot be used to determine whether a reaction will proceed in the direction as written undernon-standard conditions.Answer: DObjective: 3.3Global LO: G76) The change in enthalpy (△H) for the complete oxidation of a fatty acid is different dependingon whether it occurs via a biochemical pathway or combustion to CO2and H2O.Answer: FALSEObjective: 3.3Global LO: G77) A reaction at its lowest energy state for the system and with equal rates in the forward andreverse directions is said to be at ________.Answer: equilibriumObjective: 3.4Global LO: G78) A reaction at equilibrium can be driven in one direction or the other by changing the________ of reactants or products.Answer: concentrationObjective: 3.4Global LO: G79) A thermodynamically unfavorable reaction can become favorable if the mass action ratio is________ than the equilibrium mass action ratio.Answer: lessObjective: 3.4Global LO: G710) Calculate the equilibrium constant for the enzymatic hydrolysis of 0.1 M glucose-6-phosphate to glucose and inorganic phosphate given that 0.05% of the original glucose-6-phosphate remained after reaching equilibrium and the activity of water is unity.Answer: 199.8Objective: 3.4Global LO: G4

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311) The△Goof a reaction:A) will change if the temperature of the reaction is changed.B) will change if the concentration of reactants and products are changed.C) is not related to the equilibrium constant.D) can be used to calculate whether a reaction is thermodynamically favorable under definednon-standard conditions.E) can predict whether a reaction will be thermodynamically favorable under standardconditions.Answer: DObjective: 3.5Global LO: G712) Calculate the△G∘'for the reactionfructose-6-phosphate → glucose-6-phosphategiven the equilibrium constant is 1.97 and the physiological relevant temperature is 37∘C.Answer:-1.75kJ/molObjective: 3.5Global LO: G413) A thermodynamically unfavorable reaction can become favorable when coupled to a highlyendergonic reaction.Answer: FALSEObjective: 3.6Global LO: G714) A reaction with a large negative free energy of hydrolysis can be coupled to the synthesis ofATP from ADP and Pi.Answer: TRUEObjective: 3.6Global LO: G715) In a general redox reaction, the reductant becomes oxidized and the oxidant becomesreduced.Answer: TRUEObjective: 3.8Global LO: G716) The standard reduction potential is a measure of the ability of a reductant to ________ anelectron.Answer: loseObjective: 3.8Global LO: G7

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417) The standard reduction potentials for the following reactions are given below.Pyruvate + 2H++ 2e-→ lactateE∘=-0.190 VNAD++ 2H++ 2e-→ NADH/H+E∘=-0.320V.Calculate△G∘for the overall spontaneous reaction making use of the relationship between△E∘and△G∘.Answer:-25kJ/molObjective: 3.8Global LO: G4

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1Biochemistry: Concepts and Connections(Appling et al.)Chapter 4Nucleic Acids1) The difference between a nucleoside and a nucleotide is:A) the presence of uracil.B) a phosphate group.C) a phosphodiester bond.D) a 2'—H group.E) methylated cytosine.Answer: BObjective: 4.1Global LO: G72) Which statement is CORRECT?A) Both phosphodiester and glycosidic bonds in RNA and DNA are hydrolyzed in acid solution.B) Both RNA and DNA are hydrolyzed in mild alkaline solution.C) DNA is more unstable when dehydrated than when in solutionD) RNA is not hydrolyzed in mild alkaline solution.E) Both A and BAnswer: AObjective: 4.1Global LO: G23) Nucleotides are all weak acids.Answer: FALSEObjective: 4.1Global LO: G74) The nucleotide sequence of a polynucleotide chain is called the ________ structure.Answer: primaryObjective: 4.3Global LO: G75) Which of the following does NOT describe the secondary structure of DNA as proposed byWatson and Crick?A) The two strands of the double helix are stabilized by hydrogen-bonding between A and T andbetween G and C.B) The two strands of the double helix run in opposite directions.C) The distance between the 1' carbons of the deoxyribose units is the same between the A-T andthe G-C base pair.D) The phosphate deoxyribose backbones of the helix are on the outside.E) The base pairs are stacked on one other with their planes at 180oto the helix axis.Answer: EObjective: 4.5Global LO: G7

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26) An important observation that assisted in the elucidation of the secondary structure of DNAwas that the mole percent adenine was almost always the same as the mole percent of thymine.Answer: TRUEObjective: 4.5Global LO: G77) The mode of replication of DNA is BEST described as ________.Answer: semiconservativeObjective: 4.6Global LO: G68) Which of the following statements about nucleic acid secondary structure is FALSE?A) The width of the major and minor grooves is more equal in the A-from of DNA than in the B-form.B) Triple helices and G-quadruplexes can form at specific sequences in DNA.C) DNA can form cruciform structures at palindromic sequences.D) The A-form of DNA exists at high humidity, whereas the B-form exists at low humidity.E) Some nucleic acids can form a zig-zag structure or Z form.Answer: DObjective: 4.7Global LO: G79) Supercoiled DNA has a lower mobility than relaxed DNA with the same number of base pairswhen subjected to gel electrophoresis.Answer: FALSEObjective: 4.8Global LO: G210) Single-stranded RNA molecules can have extensive regions of intramolecular base pairingleading to defined secondary and tertiary structure.Answer: TRUEObjective: 4.8Global LO: G711) DNA in vivo is normally ________ supercoiled.Answer: negativelyObjective: 4.8Global LO: G712) Calculate the superhelix density of a circular DNA molecule with 210 base pairs and twonegative supercoils, assuming that there are 10.5 bp per turn of the double helix.Answer:-0.1Objective: 4.8Global LO: G4

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313) Calculate the linking numberin vivofor a plasmid that is 4200 bp in size if there is normally1 negative supercoil in every 20 base pairs of a circular DNA. Assume there are 10.5 bp per turnof the double helix.Answer:190Objective: 4.8Global LO: G414) Nucleic acids absorb light strongly in the ultraviolet region of the spectrum because theyhave ________ double-bond systems.Answer: conjugatedObjective: 4.10Global LO: G715) The melting temperature of DNA ________ with increasing G plus C content.Answer: increasesObjective: 4.10Global LO: G216) Expression of genetic information involves first ________ then ________.Answer: transcription, translationObjective: 4.11Global LO: G717) Restriction endonucleases are useful in gene cloning because:A) they can cut DNA at specific sequences.B) they can join DNA molecules that have been cut at specific sequences.C) they all make cohesive ends when they cut DNA.D) they all make 5' phosphate extensions and recessed 3' OH groups that can be rejoined byDNA ligase.E) they can both cut and rejoin DNA molecules.Answer: AObjective: 4.12Global LO: G718) Viral genomes cannot be used as vectors for making recombinant DNA molecules.Answer: FALSEObjective: 4.12Global LO: G719) Dideoxynucleotide sequence analysis is a template-directed method that makes use of chainterminators that stop DNA synthesis because they lack a 2'OH group.Answer: FALSEObjective: 4.12Global LO: G2

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420) Which of the following is a feature of X-diffraction?A) Radiation passing through a structure will be scattered only if the structure contains repeatingunits.B) Scattered radiation from repeating units in a structure will be weakened by interference.C) Scattered radiation from repeating units in a structure will be strengthened by interference.D) Short spacings in repeating structures will result in short spacings in diffraction patterns.E) The wavelength of radiation used to generate diffraction patterns must be slightly longer thanthe spacings between the repeating units of the structure.Answer: CObjective: 4.13Global LO: G2

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