Test Bank for Cell and Molecular Biology Concepts and Experiments 8th Edition Karp | Complete A ll Chapters 2024/2025

Which of the groups below is capable of only hydrophobic interactions? a) A b) B c) C d) D e) E Answer: e Difficulty: Medium Learning Objective: LO 2.3 Describe the role of noncovalent bonds in the structure of molecules such as water. Section Reference: Section 2.3 Noncovalent Bonds 2) Which of the following groups is capable of only hydrophilic interactions? d. H H C C C H H H H e.. H a.. OH b. C C C C C H H SH H H H H H H H H CH C C H H H H H NH 2 c.. C CH3 CH2 OH 2 C C C H H H NH H H OH 2 e. C C C C C H H H H H H H H H H H a. d. OH C C C H H H H H SH C O CH c. 3 OH b. C O Page 2 a) A b) B c) C d) D e) E Answer: b Difficulty: Medium Learning Objective: LO 2.3 Describe the role of noncovalent bonds in the structure of molecules such as water. Section Reference: Section 2.3 Noncovalent Bonds 3) Which of the following tripeptides would be most likely to be soluble in an organic (hydrophobic) solvent like benzene? a) N - phenylalanine - alanine - glycine – C b) N - leucine - alanine - lysine - C c) N - proline - phenylalanine - leucine - C d) N - arginine - lysine - proline - C e) N - glutamate - aspartate - glycine – C Answer: c Difficulty: Hard Learning Objective: LO 2.5 Describe the general structure and functions of biological molecules. Section Reference: Section 2.5 The Nature of Biological Molecules 4) What kind of bond results from an unequal sharing of electrons? a) ionic bond b) polar covalent bond c) H bond d) nonpolar covalent bond Answer: b Difficulty: Easy Learning Objective: LO 2.1 Describe the role of electrons in the formation of covalent bonds. Section Reference: Section 2.1 Covalent Bonds 5) Under which circumstances would electrons be most likely to be shared equally? a) when they are equidistant from nuclei b) when they are equidistant from each other Page 3 c) when atoms of the same element are sharing them d) when the atoms sharing them are different Answer: c Difficulty: Easy Learning Objective: LO 2.1 Describe the role of electrons in the formation of covalent bonds. Section Reference: Section 2.1 Covalent Bonds 6) The most electronegative atoms typically present in biological molecules are ____ and ____. a) O, C b) O, P c) O, N d) C, N e) C, Na Answer: c Difficulty: Easy Learning Objective: LO 2.1 Describe the role of electrons in the formation of covalent bonds. Section Reference: Section 2.1 Covalent Bonds 7) The most stable atoms and thus those that are typically nonreactive are the atoms that have _______. a) equal numbers of electrons and protons b) equal numbers of electrons and neutrons c) full inner shells d) full outer shells e) all covalent bonds Answer: d Difficulty: Easy Learning Objective: LO 2.1 Describe the role of electrons in the formation of covalent bonds. Section Reference: Section 2.1 Covalent Bonds 8) Why are free ionic bonds of little importance and relatively unlikely to form in living organisms? 1)Cells are composed mostly of water, which interferes with ionic bonds between free ions. 2)Cells are largely hydrophobic. 3)They are crystals. a) 1 b) 2 Page 4 c) 3 d) 1 and 2 e) 2 and 3 Answer: a Difficulty: Easy Learning Objective: LO 2.3 Describe the role of noncovalent bonds in the structure of molecules such as water. Section Reference: Section 2.3 Noncovalent Bonds 9) In a living organism, where are ionic bonds most likely to be found? a) in the cytoplasm b) between DNA strands c) deep in a protein's core where water is excluded d) on the surface of a protein e) on the surface of a lipid Answer: c Difficulty: Medium Learning Objective: LO 2.3 Describe the role of noncovalent bonds in the structure of molecules such as water. Section Reference: Section 2.3 Noncovalent Bonds 10) Which interaction is most important in enhancing the solubility of macromolecules in water? a) hydrophobic interactions b) nonpolar covalent bonds c) H bonds d) van der Waals forces e) Both hydrophobic interactions and nonpolar covalent bonds Answer: c Difficulty: Medium Learning Objective: LO 2.3 Describe the role of noncovalent bonds in the structure of molecules such as water. Section Reference: Section 2.3 Noncovalent Bonds 11) Where are hydrophobic interactions most likely to occur? a) on the surface of a water-soluble protein b) the core of a water-soluble protein c) in contact with water molecules d) between two charged molecules Page 5 e) between two ions Answer: b Difficulty: Easy Learning Objective: LO 2.3 Describe the role of noncovalent bonds in the structure of molecules such as water. Section Reference: Section 2.3 Noncovalent Bonds 12) What kind of noncovalent interaction is typified by interactions between two molecules that are so close together that they can experience weak attractive forces bonding them together? a) H bonds b) ionic bonds c) hydrophobic interactions d) polar covalent bonds e) van der Waals forces Answer: e Difficulty: Medium Learning Objective: LO 2.3 Describe the role of noncovalent bonds in the structure of molecules such as water. Section Reference: Section 2.3 Noncovalent Bonds 13) A molecule that is capable of releasing or donating a hydrogen ion is termed a(n) _______. a) base b) hydrion c) acid d) anachronism e) pain Answer: c Difficulty: Easy Learning Objective: LO 2.4 Explain the characteristics of acids, bases, and buffers. Section Reference: Section 2.4 Acids, Bases, and Buffers 14) A release of hydrogen ions to a solution would most likely ____________. a) raise pH b) lower pH c) buffer pH d) change salinity e) keep pH steady Page 6 Answer: b Difficulty: Easy Learning Objective: LO 2.4 Explain the characteristics of acids, bases, and buffers. Section Reference: Section 2.4 Acids, Bases, and Buffers 15) Why is silicon not suitable for making covalent bonds stable and strong enough to form the basis of living organisms, even though it is just below carbon on the periodic table? a) Silicon is too large for its nucleus to attract the valence electrons of neighboring atoms enough to hold molecules together sufficiently. b) Silicon is too small for its nucleus to attract the valence electrons of neighboring atoms enough to hold molecules together sufficiently. c) Silicon is too large for its nucleus to attract the protons of neighboring atoms enough to hold molecules together. d) Silicon is too small for its nucleus to attract the protons of neighboring atoms enough to hold molecules together. Answer: a Difficulty: Hard Learning Objective: LO 2.1 Describe the role of electrons in the formation of covalent bonds. Section Reference: Section 2.1 Covalent Bonds 16) The low-molecular-weight building blocks of polymers are called _______. a) minipolymers b) monoblocks c) monomers d) portions e) octamers Answer: c Difficulty: Easy Learning Objective: LO 2.5 Describe the general structure and functions of biological molecules. Section Reference: Section 2.5 The Nature of Biological Molecules 17) What bond is responsible for the branch points in glycogen and amylopectin? a)  (1—>4) glycosidic linkages b)  (1—>4) glycosidic linkages Page 7 c)  (1—>6) glycosidic linkages d)  (1—>6) glycosidic linkages e) 3'-5' phosphodiester linkages Answer: c Difficulty: Medium Learning Objective: LO 2.6 Describe the structures and functions of carbohydrates. Section Reference: Section 2.6 Carbohydrates 18) Which polysaccharide bond cannot be broken by mammalian enzymes that normally digest polysaccharides? a)  (1—>4) glycosidic linkages b)  (1—>4) glycosidic linkages c)  (1—>6) glycosidic linkages d)  (1—>6) glycosidic linkages e) phosphate ester linkages Answer: b Difficulty: Hard Learning Objective: LO 2.6 Describe the structures and functions of carbohydrates. Section Reference: Section 2.6 Carbohydrates 19) Why do sugars tend to be highly water soluble? a) because they have only a few hydroxyl groups b) because of their large numbers of hydroxyl groups c) because of their large numbers of sulfhydryl groups d) because of their large numbers of methyl groups e) because of their small molecular weights Answer: b Difficulty: Medium Learning Objective: LO 2.6 Describe the structures and functions of carbohydrates. Section Reference: Section 2.6 Carbohydrates 20) Which of the following is not a macromolecule formed by polymerization? a) proteins b) lipids Page 8 c) polynucleotides d) polysaccharides e) DNA Answer: b Difficulty: Hard Learning Objective: LO 2.5 Describe the general structure and functions of biological molecules. Section Reference: Section 2.5 The Nature of Biological Molecules 21) What is the maximum number of 100 amino acid long polypeptides that could be made? a) 10020 b) 2,000 c) 20100 d) 20101 e) 20 Answer: c Difficulty: Hard Learning Objective: LO 2.9 Explain the basis of the primary and secondary structure of a protein. Section Reference: Section 2.9 Primary and Secondary Structures of Proteins 22) How do amino acids like hydroxylysine and thyroxine, which are not among the 20 amino acids that are inserted into proteins, get into proteins? a) They are inserted directly. b) They are the result of the alteration of R groups of the 20 amino acids after their incorporation into the polypeptide. c) They are the result of the alteration of R groups of the 20 amino acids before their incorporation into the polypeptide. d) There are more than the 20 amino acids that are said to be inserted into proteins. e) Their atoms are altered by insertion into the polypeptide. Answer: b Difficulty: Medium Learning Objective: LO 2.8 Explain why the R group largely determines the properties of an amino acid. Section Reference: Section 2.8 Building Blocks of Proteins 23) Which amino acid is most likely to be found in the core of a protein? a) methionine Page 9 b) asparagine c) serine d) threonine e) glutamic acid Answer: a Difficulty: Medium Learning Objective: LO 2.8 Explain why the R group largely determines the properties of an amino acid. Section Reference: Section 2.8 Building Blocks of Proteins 24) What type of protein secondary structure is characterized as being highly extensible because of its coiled structure? a) -pleated sheet b) double helix c) -helix d) supercoiling Answer: c Difficulty: Medium Learning Objective: LO 2.9 Explain the basis of the primary and secondary structure of a protein. Section Reference: Section 2.9 Primary and Secondary Structures of Proteins 25) The  -pleated sheet is characterized by orientation of ______ the molecular axis. a) H bonds parallel to b) H bonds perpendicular to c) ionic bonds parallel to d) ionic bonds perpendicular to e) peptide bonds perpendicular to Answer: b Difficulty: Easy Learning Objective: LO 2.9 Explain the basis of the primary and secondary structure of a protein. Section Reference: Section 2.9 Primary and Secondary Structures of Proteins 26) Proteins are often composed of two or more distinct modules that fold up independently of one another. They often represent parts of a protein that function in a semi-independent manner. These modules are called ______. a) protein motifs Page 10 b) functionals c) domains d) dominoes Answer: c Difficulty: Easy Learning Objective: LO 2.10 Discuss the basis and significance of the tertiary structure of proteins. Section Reference: Section 2.10 Tertiary Structure of Proteins 27) What level of structure in proteins is held together by intermolecular R group interactions? a) primary structure b) secondary structure c) tertiary structure d) quaternary structure Answer: d Difficulty: Medium Learning Objective: LO 2.11 Describe how the structure of hemoglobin exemplifies quaternary protein structure. Section Reference: Section 2.11 Quaternary Structure of Proteins 28) Which of the following is a nucleotide? a) phosphate + ribose b) adenine + deoxyribose c) sugar + nitrogenous base d) adenine + ribose + phosphate Answer: d Difficulty: Medium Learning Objective: LO 2.18 Describe the structures and functions of nucleic acids. Section Reference: Section 2.18 Nucleic Acids Question Type: Essay 31) Which of the groups below is capable of only hydrophobic interactions? Explain your answer. Which is capable of only hydrophilic interactions? Explain your answer. Page 11 Answer: Difficulty: Medium Learning Objective: LO 2.3 Describe the role of noncovalent bonds in the structure of molecules such as water. Section Reference: Section 2.3 Noncovalent Bonds Solution: A is capable of only hydrophobic interactions. It contains no ionizable or hydrophilic groups. B is capable of only hydrophilic interactions, since it has no component with a long carbon chain or a carbon-containing ring and no nonpolar covalent linkages. It is also capable of ionization. 32) You treat a partially purified preparation of protein with a reagent that breaks bonds between sulfur atoms. Which level(s) of protein structure are likely to be affected the most? Answer: Difficulty: Medium Learning Objective: LO 2.12 Discuss the study of protein folding, including the role of molecular chaperones. Section Reference: Section 2.12 Protein Folding Solution: Both the tertiary and quaternary levels of structure would be affected since those levels are the only ones in which disulfide bonds are prominent. 33) Not all proteins are able to renature. Some proteins when exposed to heat or some other denaturing treatment are irreversibly denatured. What is an example of such a protein? Answer: Difficulty: Easy Learning Objective: LO 2.12 Discuss the study of protein folding, including the role of molecular chaperones. Section Reference: Section 2.12 Protein Folding Solution: Egg white protein and yolk are examples of proteins that are irreversibly denatured by heat. 34) You are working with an enzyme altase that you denature in the presence of urea. If altase were denatured no further by the addition of mercaptoethanol, what would that suggest to you about the enzyme? C C C C C H H H H H H H H H H H a. N H b. H C C C H H H C H H SH O OH c. OH d. C C C H H H NH H OH 2 e. H Page 12 Answer: Difficulty: Medium Learning Objective: LO 2.12 Discuss the study of protein folding, including the role of molecular chaperones. Section Reference: Section 2.12 Protein Folding Solution: The enzyme probably contained no disulfide linkages since mercaptoethanol breaks such linkages. 35) Would all proteins be likely to require exposure to mercaptoethanol in order to accomplish full denaturation? If not, what trait would a protein that did not require mercaptoethanol possess? Answer: Difficulty: Medium Learning Objective: LO 2.12 Discuss the study of protein folding, including the role of molecular chaperones. Section Reference: Section 2.12 Protein Folding Solution: Not all proteins would require mercaptoethanol to accomplish full denaturation. If a protein has no disulfide linkages, it probably would not require mercaptoethanol for full denaturation. 36) An enzyme is placed in a solution containing urea. Assuming that this protein contains no disulfide linkages, is it reasonable to suspect that it will be totally denatured by the treatment? How could you know that the enzyme has, in fact, been denatured? Why does the urea denature the tertiary structure of the enzyme? Answer: Difficulty: Hard Learning Objective: LO 2.12 Discuss the study of protein folding, including the role of molecular chaperones. Section Reference: Section 2.12 Protein Folding Solution: Placement in a urea solution should totally denature the enzyme, especially since there are no disulfide linkages. If there are extensive hydrophobic interactions between enzyme R groups, total denaturation may be difficult to accomplish. If the enzyme activity disappears, there is a good chance the enzyme has been denatured. Urea breaks up the tertiary structure by interfering with hydrophilic interactions, like H bonds. 37) Which of the following tripeptides would be most likely to be soluble in an organic (hydrophobic) solvent like benzene: N - phenylalanine - alanine - glutamine - C, N - leucine - alanine - lysine - C, N - proline - phenylalanine - leucine - C, N - arginine - lysine - proline - C, N - glutamate - aspartate - glycine - C? Explain your answer. Answer: Difficulty: Medium Page 13 Learning Objective: LO 2.8 Explain why the R group largely determines the properties of an amino acid. Section Reference: Section 2.8 Building Blocks of Proteins Solution: N - proline - phenylalanine - leucine - C would be most soluble in a hydrophobic solvent. All three amino acids are classed as nonpolar amino acids and could be soluble in benzene. In the other tripeptides, at least one of the amino acids does not belong to the nonpolar class. 40) Mammals lack the enzyme that hydrolyzes cellulose. Yet many mammals are herbivores and they eat grass and other plant material for nutrition. How can this be, given that they cannot digest the food they are eating? Answer: Difficulty: Easy Learning Objective: LO 2.6 Describe the structures and functions of carbohydrates. Section Reference: Section 2.6 Carbohydrates Solution: While these animals lack the enzyme that digests cellulose, bacteria that reside within their digestive tracts possess it. There is a symbiotic relationship between the two organisms. The herbivores seek out and eat the grass; the bacteria in their digestive tract digest it. What the bacteria don't use, the herbivore does. 42) What are some possible explanations for the branched structure of glycogen? Answer: Difficulty: Medium Learning Objective: LO 2.6 Describe the structures and functions of carbohydrates. Section Reference: Section 2.6 Carbohydrates Solution: First, branching allows more efficient storage of energy. More glucose monomers can be stored in a smaller space. Second, branching creates more free ends on the structure. This would allow glycogen to be disassembled more rapidly when free glucose is needed and would also allow quicker assembly when glycogen is being constructed. 43) Scientists have sequenced proteins by using specific proteases to "clip" a purified protein preparation between two specific amino acids, thus forming a number of moderately sized fragments; they have used acid hydrolysis to produce smaller fragments. Each fragment can then be sequenced by breaking the moderate fragments into dipeptides that are easily sequenced. The fragments below are obtained after the initial enzymatic cleavages. Can you deduce the sequence of the original polypeptide? (HINT: the original cleavages at specific locations differ depending on which proteolytic enzyme was used to create each fragment; this causes an overlap in the fragments' sequences.) The final polypeptide should have 18 amino acid residues. Page 14 N - ala - ala - gluN - aspN - met - C N - iso - pro - aspA - try - thr - C N - met - cys - leu - lys - phe - arg - aspA - C N - aspN - met - cys - leu - lys - C N - aspA - try - thr - phe - tyr - ala - ala - C Answer: Difficulty: Hard Learning Objective: LO 2.9 Explain the basis of the primary and secondary structure of a protein. Section Reference: Section 2.9 Primary and Secondary Structures of Proteins Solution: N- iso - pro - aspA - try - thr - phe - tyr - ala - ala - gluN - aspN - met - cys - leu - lys - phe - arg - aspA - C 44) Many so-called temperature-sensitive mutations have been discovered in a wide variety of organisms. These are proteins that are non-functional at higher temperatures, while, at lower temperatures (often just a few degrees lower), they function normally. For example, the coloration patterns in Siamese Cats arise from a temperature-sensitive mutation. An enzyme required for the synthesis of dark pigment is unable to function in areas close to the body where normal physiological temperatures prevail. However, at the tips of the ears, paws, the tip of the tail and other extremities where the temperature is slightly lower, the enzyme works correctly and dark pigment is produced. What is happening at the molecular level that explains this? Answer: Difficulty: Easy Learning Objective: LO 2.14 Trace the history of our understanding of the role of molecular chaperones in protein folding. Section Reference: Section 2.14 Experimental Pathways: Chaperones - Helping Proteins Reach Their Proper Folded State Solution: In warmer areas of the organism, the temperature is just high enough to denature the enzyme in question. Since it is denatured, it will not work properly and dark pigment will not be produced in those areas.