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

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    1 Biochemistry: Concepts and Connections (Appling et al.) Chapter 1 Biochemistry and the Language of Chemistry 1) The water content in the human body is approximately: A) 90%. B) 80%. C) 70%. D) 60%. E) 50%. Answer: C 2) 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: B Objective: 1.2 3) Nearly all proteins contain: A) cobalt. B) phosphorus. C) selenium. D) sulfur. E) none of the above. Answer: D Objective: 1.2 Global LO: G7 4) 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: E Objective: 1.2 Global LO: G7

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    2 5) Which of the following is NOT classed as a lipid? A) Cholesterol B) Palmitic acid C) Glycerol D) Phosphatidyl serine E) Triacylglycerol Answer: C Objective: 1.2 Global LO: G7 6) Amino acids and simple organic compounds like carbon dioxide and hydrogen cyanide cannot be produced without the use of enzymes. Answer: FALSE Objective: 1.2 Global LO: G7 7) Oxidation - reduction reactions, which are the basis of many biochemical reactions and pathways, cannot take place in the absence of oxygen. Answer: FALSE Objective: 1.2 Global LO: G7 8) Many biochemical reactions that form biopolymers from monomeric units involve the removal of water. Answer: TRUE Objective: 1.2 Global LO: G7 9) The principle component of a biological membrane is a triglyceride. Answer: FALSE Objective: 1.2 Global LO: G7 10) The chemical element ________ has a role in both transfer of energy as well as in the structure of nucleic acids. Answer: phosphorus Objective: 1.2 Global LO: G7 11) List the four major classes of biological macromolecules. Answer: lipids, carbohydrates, proteins, nucleic acids Objective: 1.2 Global LO: G7

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    3 12) An amphipathic molecule provides the foundation for biological membranes because they have both ________ and ________ functional groups. Answer: hydrophobic, hydrophilic Objective: 1.2 Global LO: G7 13) Genomics is concerned with the entire ________, while ________ is focused on identifying all of the proteins of a cell. Answer: genome, proteomics Objective: 1.5 Global LO: G1

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    1 Biochemistry: Concepts and Connections (Appling et al.) Chapter 2 The Chemical Foundation of Life: Weak Interactions in an Aqueous Environment 1) 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 a carboxylate group. D) a van der Waals interaction. E) an interaction between — NH 3 + and a water molecule. Answer: B Objective: 2.1 Global LO: G7 2) The most important noncovalent interaction in biochemistry is the ________ bond. Answer: hydrogen Objective: 2.1 Global LO: G7 3) 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: E Objective: 2.2 Global LO: G2 4) Which of the following in biological compounds are sufficiently electronegative to serve as strong donors in a hydrogen bond? A) Hydrogen and oxygen B) Oxygen and nitrogen C) Nitrogen and hydrogen D) Hydrogen and carbon E) Nitrogen and carbon Answer: B Objective: 2.2 Global LO: G7 5) Hydrogen bonds share features of both covalent and noncovalent bonds. Answer: TRUE Objective: 2.2 Global LO: G2

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    2 6) 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 above Answer: E Objective: 2.3 Global LO: G2 7) Water is both a hydrogen bond donor and acceptor. Answer: TRUE Objective: 2.3 Global LO: G2 8) Amphipathic molecules are not able to interact via van der Waals forces. Answer: FALSE Objective: 2.3 Global LO: G2 9) Ionic compounds can be readily dissolved in water because the high dielectric constant of water screens and decreases the ________ force between the oppositely charged ions. Answer: electrostatic Objective: 2.3 Global LO: G7 10) The ________ describes the tendency for hydrophobic molecules to aggregate because of the exclusion of water with the consequent increase of entropy of the solvent. Answer: hydrophobic effect Objective: 2.3 Global LO: G7 11) Glycine cannot serve as a buffer because it has two ionizable groups. Answer: FALSE Objective: 2.4 Global LO: G7 12) The average charge on an amino acid below its pI will be positive. Answer: TRUE Objective: 2.4 Global LO: G2 13) Calculate the acid dissociation constant K a of a 0.2 M solution of weak acid that is 0.1% ionized. Answer: 2 × 10 - 7 Objective: 2.4 Global LO: G4

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    3 14) Calculate the pH of a 0.1 M phosphate buffer (pKa = 6.86) that contains equal amounts of acid and conjugate base. Answer: 6.86 Objective: 2.4 Global LO: G4 15) Calculate the pH of a 0.2 M acetate buffer (pKa = 4.77) that contains twice as much acid as conjugate base. Answer: 4.47 Objective: 2.4 Global LO: G4 16) The pK a of each amino acid residue in a protein will not be influenced by the adjacent residue. Answer: FALSE Objective: 2.5 Global LO: G2 17) Calculate the pH at the end of an enzyme - catalyzed reaction if it were carried out in a 0.1 M phosphate buffer, pH 6.86 and 0.005 M of acid was produced during the reaction? Answer: 6.77 Objective: 2.5 Global LO: G4 18) If hydroxide is added to an amino acid it will become increasingly ________ charged. Answer: negatively Objective: 2.6 Global LO: G7 19) Calculate the pH of a weak acid that is 0.2% ionized in a 0.2 M solution. Answer: 3.39 Objective: 2.6 Global LO: G4 20) The net charge on an amino acid at its isoelectric point (pI) is ________. Answer: zero Objective: 2.7 Global LO: G7

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    4 21) 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 on proteins. C) the positively charged DNA is electrostatically attracted to negatively charged regions on proteins. D) proteins and DNA interact using mainly hydrophobic interactions. E) both proteins and DNA are at their isoelectric points at physiological pH and tend to aggregate. Answer: B Objective: 2.8 Global LO: G2 22) Small ions in biological fluids: A) encourage strong electrostatic interactions between oppositely charged macroions at low ionic strengths. B) encourage strong electrostatic interactions between oppositely charged macroions at high ionic 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: A Objective: 2.8 Global LO: G7

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    1 Biochemistry: Concepts and Connections (Appling et al.) Chapter 3 The Energetics of Life 1) Which of the following statements is FALSE? A) Organisms are open systems as they can exchange both energy and materials with their environments. 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: C Objective: 3.1 Global LO: G7 2) 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: C Objective: 3.2 Global LO: G2 3) A biochemical reaction will proceed in the direct ion as written if: A) △ G = zero. B) △ G > 0. C) △ G < 0. D) △ H > 0. E) △ H < 0. Answer: C Objective: 3.2 Global LO: G2 4) Life is an irreversible process, such that it never comes to equilibrium. Answer: TRUE Objective: 3.2 Global LO: G2

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    2 5) The equil ibrium 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 under non - standard conditions. Answer: D Objective: 3.3 Global LO: G7 6) The change in enthalpy ( △ H ) for the complete oxidation of a fatty acid is different depending on whether it occurs via a biochemical pathway or combustion to CO 2 and H 2 O. Answer: FALSE Objective: 3.3 Global LO: G7 7) A reaction at its lowest energy state for the system and wi th equal rates in the forward and reverse directions is said to be at ________. Answer: equilibrium Objective: 3.4 Global LO: G7 8) A reaction at equilibrium can be driven in one direction or the other by changing the ________ of reactants or products. Answer: concentration Objective: 3.4 Global LO: G7 9) A thermodynamically unfavorable reaction can become favorable if the mass action ratio is ________ than the equilibrium mass action ratio. Answer: less Objective: 3.4 Global LO: G7 10) 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: 199.8 Objective: 3.4 Global LO: G4

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    3 11) The △ G o of 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 the rmodynamically favorable under defined non - standard conditions. E) can predict whether a reaction will be thermodynamically favorable under standard conditions. Answer: D Objective: 3.5 Global LO: G7 12) Calculate the △ G ∘ ' for the reaction fructose - 6 - phosphate → glucose - 6 - phosphate given the equilibrium constant is 1.97 and the physiological relevant temperature is 37 ∘ C. Answer: - 1.75kJ/mol Objective: 3.5 Global LO: G4 13) A thermodynamically unfavorable reaction can become favorable when coupled to a highly endergonic reaction. Answer: FALSE Objective: 3.6 Global LO: G7 14) A reaction with a large negative free energy of hydrolysis can be coupled to the synthesis of ATP from ADP and P i . Answer: TRUE Objective: 3.6 Global LO: G7 15) In a general redox reaction, the reductant becomes oxidized and the oxidant becomes reduced. Answer: TRUE Objective: 3.8 Global LO: G7 16) The standard reduction potential is a measure of the ability of a reductant to ________ an electron. Answer: lose Objective: 3.8 Global LO: G7

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    4 17) The standard reduction potentials for the following reactions are given below. Pyruvate + 2H + + 2e - → lactate E ∘ = - 0.190 V NAD + + 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/mol Objective: 3.8 Global LO: G4

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    1 Biochemistry: Concepts and Connections (Appling et al.) Chapter 4 Nucleic Acids 1) 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: B Objective: 4.1 Global LO: G7 2) 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 solution D) RNA is not hydrolyzed in mild alkaline solution. E) Both A and B Answer: A Objective: 4.1 Global LO: G2 3) Nucleotides are all weak acids. Answer: FALSE Objective: 4.1 Global LO: G7 4) The nucleotide sequence of a polynucleotide chain is called the ________ structure. Answer: primary Objective: 4.3 Global LO: G7 5) Which of the following does NOT describe the secondary structure of DNA as proposed by Watson and Crick? A) The two strands of the double helix are stabilized by hydrogen - bonding between A and T and between 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 and the 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 180 o to the helix axis. Answer: E Objective: 4.5 Global LO: G7

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    2 6) An important observation that assisted in the elucidation of the secondary structure of DNA was that the mole percent adenine was almost always the same as the mole percent of thymine. Answer: TRUE Objective: 4.5 Global LO: G7 7) The mode of replication of DNA is BEST described as ________. Answer: semiconservative Objective: 4.6 Global LO: G6 8) 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: D Objective: 4.7 Global LO: G7 9) Supercoiled DNA has a lower mobility than relaxed DNA with the same number of base pairs when subjected to gel electrophoresis. Answer: FALSE Objective: 4.8 Global LO: G2 10) Single - stranded RNA molecules can have extensive regions of intramolecular base pairing leading to defined secondary and tertiary structure. Answer: TRUE Objective: 4.8 Global LO: G7 11) DNA in vivo is normally ________ supercoiled. Answer: negatively Objective: 4.8 Global LO: G7 12) Calculate the superhelix density of a circular DNA molecule with 210 base pairs and two negative supercoils, assuming that there are 10.5 bp per turn of the double helix. Answer: - 0.1 Objective: 4.8 Global LO: G4

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    3 13) Calculate the linking number in vivo for a plasmid that is 4200 bp in size if there is normally 1 negative supercoil in every 20 base pairs of a circular DNA. Assume there are 10.5 bp per turn of the double helix. Answer: 190 Objective: 4.8 Global LO: G4 14) Nucleic acids absorb light strongly in the ultraviolet region of the spectrum because they have ________ double - bond systems. Answer: conjugated Objective: 4.10 Global LO: G7 15) The melting temperature of DNA ________ with increasing G plus C content. Answer: increases Objective: 4.10 Global LO: G2 16) Expression of genetic information involves first ________ then ________. Answer: transcription, translation Objective: 4.11 Global LO: G7 17) 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 by DNA ligase. E) they can both cut and rejoin DNA molecules. Answer: A Objective: 4.12 Global LO: G7 18) Viral genomes cannot be used as vectors for making recombinant DNA molecules. Answer: FALSE Objective: 4.12 Global LO: G7 19) Dideoxynucleotide sequence analysis is a template - directed method that makes use of chain terminators that stop DNA synthesis because they lack a 2'OH group. Answer: FALSE Objective: 4.12 Global LO: G2

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    4 20) Which of the following is a feature of X - diffraction? A) Radiation passing through a structure will be scattered only if the structure contains repeating units. 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 than the spacings between the repeating units of the structure. Answer: C Objective: 4.13 Global LO: G2

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