OpenStax Microbiology Test Bank Chapter 7: Microbial Biochemistry | 2022 LATEST UPDATE

OpenStax Microbiology Test Bank Chapter 7: Microbial Biochemistry Chapter 7: Microbial Biochemistry * = Correct answer Multiple Choice 1. Which of the following is the best definition of a macronutrient? A. a trace element B. a vitamin C. an organic molecule necessary for life D. the most abundant elements found in living cells* Difficulty: Easy ASM Standard: N/A 2. Amino groups are an important component of which of the following macromolecules? A. carbohydrates B. lipids C. nucleic acids D. proteins* Difficulty: Easy ASM Standard: N/A 3. The building blocks of polymers are called which of the following? A. inorganic molecules B. macromolecules C. monomers* D. nucleic acids Difficulty: Easy ASM Standard: N/A 4. Which of the following is not one of the four major types of carbon-based macromolecules found in cells? A. carbohydrates B. lipids C. macronutrients* D. nucleic acids Difficulty: Easy ASM Standard: N/A 5. Which of the following is the typical, stable shape of glucose in cells? A. a branched chain B. a double ring Page 1 of 19 OpenStax Microbiology Test Bank Chapter 7: Microbial Biochemistry C. a ring* D. a tetrahedron Difficulty: Easy ASM Standard: N/A 6. In which form do plants generally store sugar molecules? A. cellulose B. chitin C. glycogen D. starch* Difficulty: Easy ASM Standard: N/A 7. Which term specifically describes fatty acids that do not have any double bonds, triple bonds, or rings? A. esterified B. polyunsaturated C. saturated* D. unsaturated Difficulty: Easy ASM Standard: N/A 8. Which of the following best describes the difference between steroids and sterols? A. Steroids are the most common type of sterol. B. Steroids contain rings, whereas sterols do not. C. Sterols are a type of steroid with an OH group.* D. Sterols are present in prokaryotes and steroids are not. Difficulty: Moderate ASM Standard: N/A 9. Which best describes oligopeptides? A. a molecule consisting of two amino acids B. long chains of amino acids C. polymers of about 20 amino acids* D. polymers of about 50 amino acids Difficulty: Easy ASM Standard: N/A 10. Which of the following is not a lipid? A. a fatty acid B. a glyceraldehyde* C. a wax Page 2 of 19 OpenStax Microbiology Test Bank Chapter 7: Microbial Biochemistry D. an isoprenoid Difficulty: Easy ASM Standard: N/A 11. How many single covalent bonds can oxygen form? A. one B. two* C. three D. four Difficulty: Moderate ASM Standard: N/A 12. Which of the following molecules is an organic molecule? A. CO2 B. CaCO3 C. CH3OH* D. H2O Difficulty: Moderate ASM Standard: N/A 13. Which of the following is the best example of a micronutrient? A. carbon B. nitrogen C. phosphorus D. potassium* Difficulty: Easy ASM Standard: N/A 14. Which of the following best describes glucose, fructose, and galactose? A. achiral B. enantiomers C. stereoisomers D. structural isomers* Difficulty: Moderate ASM Standard: N/A 15. Why does it matter which enantiomer of a molecule is used for a medication? A. Enantiomers can have different pharmacologic effects and only one may be effective.* B. It is usually easier to prepare one enantiomer than mixtures of both. C. The D form is typically more effective than the L form. D. The L form is typically more effective than the D form. Page 3 of 19 OpenStax Microbiology Test Bank Chapter 7: Microbial Biochemistry Difficulty: Moderate ASM Standard: N/A 16. Which of the following shows a ketone? A. a carboxylic acid B. an ester C. an internal carbonyl group* D. an internal ether Difficulty: Moderate ASM Standard: N/A 17. Which of the following types of bonds joins monosaccharides together to form a polysaccharide? A. glycosidic bonds* B. hydrogen bonds C. peptide bonds D. phosphodiester bonds Difficulty: Moderate ASM Standard: N/A 18. Which of the following best describes the molecule lactose? A. disaccharide* B. monosaccharide C. polysaccharide D. trisaccharide Difficulty: Moderate ASM Standard: N/A 19. Which of the following is an important component of insect exoskeletons? A. cellulose B. chitin* C. glycogen D. starch Difficulty: Moderate ASM Standard: N/A 20. Which describes the hydrocarbon tails in the plasma membrane? A. amphipathic B. hydrophilic Page 4 of 19 OpenStax Microbiology Test Bank Chapter 7: Microbial Biochemistry C. hydrophobic* D. polar Difficulty: Moderate ASM Standard: N/A 21. In a protein, which type of chemical linkage joins the amino acids? A. disulfide linkages B. glycosidic linkages or bonds C. hydrogen bonds D. peptide bonds* Difficulty: Moderate ASM Standard: N/A 22. Which is a common type of secondary structure of proteins? A. the α helix* B. the β helix C. the Δ helix D. the ω helix Difficulty: Moderate ASM Standard: N/A 23. Disulfide bridges are most important in which of the following? A. primary structure of proteins B. secondary structure of proteins C. structure of carbohydrates D. tertiary structure of proteins* Difficulty: Moderate ASM Standard: N/A 24. Which enantiomers rotate plane polarized light in a clockwise direction? A. + or d* B. + or l C. – or d D. – or l Difficulty: Moderate ASM Standard: N/A 25. C6H12O6 is an example of which type of molecule? A. amino acid B. fatty acid C. monosaccharide* Page 5 of 19 OpenStax Microbiology Test Bank Chapter 7: Microbial Biochemistry D. nucleotide Difficulty: Moderate ASM Standard: N/A 26. The phospholipid molecules in the plasma membrane are which of the following? A. amphipathic* B. hydrophilic only C. hydrophobic only D. in the shape of micelles Difficulty: Moderate ASM Standard: N/A 27. Amylose is a component of which of the following? A. cellulose B. disaccharides C. nucleotides C. starch* Difficulty: Moderate ASM Standard: N/A 28. Chitin is a polymer of which of the following? A. amylase and amylopectin B. glycosaminoglycan B. N-acetyl glucosamine* C. N-acetyl muramic acid Difficulty: Difficult ASM Standard: N/A 29. Dextromethorphan and levomethorphan are best described as which of the following? A. achiral B. biologically identical C. enantiomers* D. structural isomers Difficulty: Difficult ASM Standard: N/A 30. Which type of molecule is CH3(CH2)14COOH? A. amino acid B. fatty acid* C. monosaccharide D. nucleotide Page 6 of 19 OpenStax Microbiology Test Bank Chapter 7: Microbial Biochemistry Difficulty: Difficult ASM Standard: N/A 31. A triglyceride contains which subcomponents? A. a glycerol and two fatty acids B. a glycerol and two sugars C. a glycerol and three fatty acids* D. a glycerol and three sugars Difficulty: Moderate ASM Standard: N/A 32. The phospholipids of the plasma membrane contain which subcomponents? A. a wax, a glycerol, and a phosphate group B. two fatty acids, a glycerol, and a phosphate group* C. three fatty acids, a glycerol, and a phosphate group D. four sphingolipids and a phosphate group Difficulty: Difficult ASM Standard: N/A 33. Which monomers make up lipids? A. amino acids B. fatty acids C. lipids do not consist of monomers* D. monosaccharides Difficulty: Difficult ASM Standard: N/A 34. Which are the components found in starch? A. amylose and amylopectin* B. amylose and glycogen C. cellulose and glycogen D. glucosamine and muramic acid Difficulty: Difficult ASM Standard: N/A 35. Which of the following is not true of triglycerides? A. They are a type of phospholipid.* B. They are considered simple lipids. C. They are hydrophobic. D. They contain glycerol and three fatty acids. Difficulty: Difficult Page 7 of 19 OpenStax Microbiology Test Bank Chapter 7: Microbial Biochemistry ASM Standard: N/A 36. FAME analysis involves which of the following? A. gas chromatography* B. high-pressure liquid chromatography C. immunological testing D. mass spectrometry Difficulty: Difficult ASM Standard: N/A True/False 37. Polysaccharides generally have a sweet taste. Answer: False Difficulty: Easy ASM Standard: N/A 38. Cellulose is an important structural component of plant cell walls. Answer: True Difficulty: Easy ASM Standard: N/A 39. A denatured protein has lost its primary structure. Answer: False Difficulty: Moderate ASM Standard: N/A 40. The MALDI-TOF method includes irradiation of the sample. Answer: True Difficulty: Moderate ASM Standard: N/A 41. Proteins embedded within the plasma membrane are called integral proteins. Answer: True Difficulty: Moderate ASM Standard: N/A 42. Disulfide bridges are a major component of the secondary structure of a protein. Answer: False Page 8 of 19 OpenStax Microbiology Test Bank Chapter 7: Microbial Biochemistry Difficulty: Moderate ASM Standard: N/A 43. The structure of β-pleated sheets is maintained by covalent bonds and ionic interactions. Answer: False Difficulty: Moderate ASM Standard: N/A 44. The presence of poly-β-hydroxybutyrate granules is used in the classification of species of Pseudomonas bacteria. Answer: False Difficulty: Difficult ASM Standard: N/A 45. Some plants use leghemoglobin to bind oxygen. Answer: True Difficulty: Difficult ASM Standard: N/A 46. Xanthophylls are a type of isoprenoid. Answer: True Difficulty: Difficult ASM Standard: N/A Matching 47. Match each term with the best definition. A. primary protein structure i. created from localized folding that creates helices and sheets primarily stabilized by hydrogen bonding B. secondary protein structure ii. produced by joining more than one polypeptide chain by interactions including hydrogen bonding, hydrophobic interactions, disulfide bonds, and ionic interactions C. tertiary protein structure iii. created from interactions between relatively distant amino acids, including hydrogen bonding, hydrophobic interactions, disulfide bonds, and ionic interactions D. quaternary protein structure iv. refers to the sequence of amino acids connected by peptide bonds Answers: A. iv., B. i., C. iii., D. ii. Difficulty: Easy ASM Standard: N/A Page 9 of 19 OpenStax Microbiology Test Bank Chapter 7: Microbial Biochemistry 48. Match each molecule with the best description. A. FAME i. uses saponification to release fatty acids for further analysis to produce gas chromatograms B. MALDI-TOF ii. produces gas chromatograms of fatty acids to compare with references C. PLFA iii. uses HPLC, digestion, then mass spectrometry D. proteomic analysis iv. produces a mass spectrum to compare with references without requiring HPLC Answers: A. ii., B. iv., C. i., D. iii. Difficulty: Difficult ASM Standard: N/A 49. Match each molecule with type of monomer it exemplifies. A. adenosine triphosphate i. amino acid B. alanine ii. lipid C. cholesterol iii. monosaccharide D. ribose iv. nucleotide Answers: A. iv., B. i., C. ii., D. iii. Difficulty: Moderate ASM Standard: N/A 50. Match each molecule with a type of functional group it contains. A. NH2CH2CH3 i. ketone B. CH3COCH3 ii. carboxylic acid C. CH3CH2OH iii. amino D. CH3CH2COOH iv. sulfhydryl E. CH3CH2SH v. hydroxyl Answers: A. iii., B. i., C. v., D. ii., E. iv. Difficulty: Moderate ASM Standard: N/A 51. Match each molecule with the class of macromolecules it exemplifies. A. β-carotene i. protein B. chitin ii. lipid C. hemoglobin iii. nucleic acid D. RNA iv. carbohydrate Answers: A. ii., B. iv., C. i., D. iii. Difficulty: Difficult ASM Standard: N/A Fill in the Blank 52. ________ tissue stores energy in the form of triglycerides. Page 10 of 19 OpenStax Microbiology Test Bank Chapter 7: Microbial Biochemistry Answer: Adipose (fat) Difficulty: Easy ASM Standard: N/A 53. ________ fatty acids are usually liquid at room temperature. Answer: Unsaturated Difficulty: Easy ASM Standard: N/A 54. Another term for triglyceride is ________. Answer: triacylglycerol Difficulty: Moderate ASM Standard: N/A 55. Sulfhydryl groups in amino acids join together to form ________. Answer: disulfide bridges (disulfide bonds) Difficulty: Moderate ASM Standard: N/A 56. Sebum contains wax esters, triacylglycerol, and ________. Answer: squalene Difficulty: Difficult ASM Standard: N/A 57. ________ is a branched lipid that is a building block of β-carotene. Answer: Isoprene Difficulty: Moderate ASM Standard: N/A 58. Fungi produce ________ in their cell membranes, which serves a similar function as cholesterol in animal cell membranes. Answer: ergosterol Difficulty: Moderate ASM Standard: N/A 59. ________ is a hormone produced in response to stress; it is marketed in a synthetic form as hydrocortisone to reduce skin irritation and inflammation. Answer: Cortisol Page 11 of 19 OpenStax Microbiology Test Bank Chapter 7: Microbial Biochemistry Difficulty: Moderate ASM Standard: N/A 60. The presence or absence of the storage molecule ________ can be used to identify some species of Pseudomonas. Answer: poly-β-hydroxybutyrate Difficulty: Difficult ASM Standard: N/A 61. ________ is an important globular protein that has four subunits, including two α peptides and two β peptides. Answer: Hemoglobin Difficulty: Difficult ASM Standard: N/A Short Answer 62. Some lipid molecules have a distinctive four-ringed structure and often function as hormones. What is the name for this group of hormones, and what are two examples of molecules in this group? Sample Answer: Steroids, including sterols, have this structure. Cholesterol and steroid hormones are examples. Difficulty: Easy ASM Standard: N/A 63. What is the difference between a steroid and a sterol? Sample Answer: Steroids lack an –OH group present in sterols. Difficulty: Easy ASM Standard: N/A 64. What is a unit membrane? Sample Answer: A unit membrane is the standard membrane of plasma membranes and eukaryotic organelles. Unit membranes have a phospholipid bilayer structure. Difficulty: Moderate ASM Standard: N/A 65. Draw an example of a type of dehydration reaction (a chemical reaction) important in living organisms. Sample Answer: Polymers are often made using dehydration reactions. For example, amino acids are joined together by removing water (a dehydration reaction). Page 12 of 19 OpenStax Microbiology Test Bank Chapter 7: Microbial Biochemistry Difficulty: Easy ASM Standard: N/A 66. What is the function of cholesterol in cell membranes? Sample Answer: Cholesterol makes cell membranes more resilient. [While the chapter only mentions that cholesterol strengthens cell membranes, students may also say that cholesterol helps regulate membrane fluidity.] Difficulty: Moderate ASM Standard: N/A 67. How many glycosidic linkages are in the molecule below? Sample Answer: There are two glycosidic linkages in this molecule. Difficulty: Moderate ASM Standard: N/A 68. What type of chemical reaction is needed to separate this molecule into three fatty acids and glycerol? Sample Answer: To break down this molecule, water must be added (i.e., a hydrolysis reaction). Page 13 of 19 OpenStax Microbiology Test Bank Chapter 7: Microbial Biochemistry Difficulty: Moderate ASM Standard: N/A 69. Indicate the α carbon on the amino acid below. Sample Answer: The α carbon is the carbon to which the amino group, carboxyl group, hydrogen, and R group are joined. Difficulty: Moderate ASM Standard: N/A 70. Consider the molecule below. Of the four major types of important biological molecules, which type is this? How can you tell? Explain why it fits into that group and then explain why it does not fit into each of the other three groups. Sample Answer: This molecule is a lipid. It is nonpolar and consists of only carbon and hydrogen. It is not a monosaccharide, because it does not have –OH groups. Sugars do have –OH groups and an aldehyde or ketone (when linear). They can also form rings. It is not an amino acid, because it lacks an amino group and a carboxyl group. Finally, it is not a Page 14 of 19 OpenStax Microbiology Test Bank Chapter 7: Microbial Biochemistry nucleotide, because it lacks a phosphate group, a sugar, and a nitrogenous base (let alone any nitrogen). It does not contain a sugar for the reasons already discussed. Difficulty: Moderate ASM Standard: N/A 71. Identify the functional group or groups in this molecule: CH3CH2CHO Sample Answer: This molecule contains an aldehyde. Difficulty: Moderate ASM Standard: N/A 72. Why is glucose usually found in nature as a ring rather than as a linear structure? Sample Answer: Sugars can form a ring through the interaction of a hydroxyl group and a carbonyl group. When the ring is the right size for maintaining appropriate bond angles (reducing ring strain), then a ring is more stable than the linear molecule. Glucose has six carbons and can form either a six-membered ring or a five-membered ring. Difficulty: Moderate ASM Standard: N/A 73. Compare the structures of starch, glycogen, and cellulose. Explain why humans cannot use cellulose as a major source of energy even though it contains glucose molecules. Sample Answer: Although starch, glycogen, and cellulose are all polymers of glucose, they have different structures, resulting in different properties. Starch consists of two types of chains, a straight chain (amylose) and a branched chain (amylopectin). Glycogen consists of one type of chain, which is more branched than amylopectin. Cellulose is not branched but has linkages between its linear chains that make it strong. Because cellulose has different glycosidic linkages than those of starch and glycogen, a different enzyme is needed to break it down and human do not produce this enzyme. Difficulty: Difficult ASM Standard: N/A 74. What are micelles and why is it energetically favorable for them to form? Sample Answer: Micelles are spherical structures that assemble from phospholipids with the phosphate groups toward the outside and the lipid tails toward the inside. This is energetically favorable because the lipid tails are hydrophobic and it would take more energy to keep them in contact with water than in contact with each other. Difficulty: Difficult ASM Standard: N/A 75. Is the α carbon of this molecule chiral? Explain. Page 15 of 19 OpenStax Microbiology Test Bank Chapter 7: Microbial Biochemistry Sample Answer: Yes, the α carbon of this molecule is chiral because it has four different groups attached to it and, therefore, has two mirror image forms. Difficulty: Difficult ASM Standard: N/A Brief Essay Essay Question Rubric RATING Failing Below Average Competent Advanced Criteria for evaluati on Answer does not provide an argument. Answer contains inaccuracies. Writing is poor and contains numerous grammatical mistakes and misspellings. Answer fails to provide examples to support an argument. Writing is poor and grammatical errors are common. Answer is somewhat incoherent. Answer provides an argument with one or two examples that support it. Writing is acceptable for the college level but may contain one or two grammatical mistakes or misspellings. Answer clearly provides an argument with two or more excellent examples that support it; student makes the argument clearly and eloquently. Answer is well organized and free of grammatical errors and misspellings. POINT VALUE 0 1 2 3 Assume rating/grading scale for the question ranges from 0 to 3 points. 76. When a plasma membrane is damaged, it reseals to keep the lipid bilayer intact. Explain how this process happens and why it is energetically favorable. Answer: Student answers will vary but should include components of the following. The middle of the plasma membrane is a hydrophobic lipid layer. It is energetically favorable for the hydrophobic molecules to contact each other rather than being in contact with the watery material inside and outside the cell. For this reason, it is energetically favorable for the membrane to reseal itself when damaged. Difficulty: Moderate Page 16 of 19 OpenStax Microbiology Test Bank Chapter 7: Microbial Biochemistry ASM Standard: N/A 77. Explain how the structure of the plasma membrane affects what can pass through it. Answer: Student answers will vary but should include components of the following. The middle of the membrane is hydrophobic, so only small, uncharged molecules can pass through easily. Molecules that are polar, such as water, may pass through if they are sufficiently small. However, even very small ions, such as Na+ , are unable to pass without assistance (e.g., by passing through a protein channel). Larger, nonpolar molecules, such as steroid hormones, can pass through the membrane. Difficulty: Moderate ASM Standard: N/A 78. Compare the types of interactions that are responsible for the four different levels of protein structure. Answer: Student answers will vary but should include components of the following. Primary protein structure is determined by the sequence of amino acids, which are joined together by peptide bonds. Secondary structure results from hydrogen bonding between amino acids that are relatively close together, forming α-helices and β-pleated sheets. Tertiary structure involves interactions between amino acids that are farther apart and results from hydrogen bonding, hydrophobic interactions, disulfide bonds, and ionic interactions. Quaternary structure results from the same interactions as tertiary structure but involves more than one polypeptide chain. Difficulty: Moderate ASM Standard: N/A 79. Look at the phospholipid molecule below. Compare the shape of saturated and unsaturated fatty acids and think about what would happen if you packed together many phospholipids with a saturated fatty acids compared with packing together many phospholipids with unsaturated fatty acids. How do you think the plasma membrane might act differently if it has a higher proportion of saturated fatty acids versus a higher proportion of unsaturated fatty acids? Page 17 of 19 OpenStax Microbiology Test Bank Chapter 7: Microbial Biochemistry Answer: Student answers will vary but should include the following. Saturated fatty acids can pack tightly because they are straight. In contrast, unsaturated fatty acids are kinked and this causes them to pack less tightly. If the temperature were increased without any changes in the composition of the membrane, then the membrane would become too fluid if it had a high proportion of unsaturated fatty acids. By increasing the amount of saturation in the membrane, organisms can make the membrane more solid as the temperature increases. Organisms can also make the membrane more flexible as the temperature drops by increasing the amount of unsaturation. Difficulty: Moderate ASM Standard: N/A 80. Think about the structure of the plasma membrane and about how proteins form threedimensional structures. How do you think hydrophobic interactions affect an integral membrane protein? Where would hydrophobic amino acids be located on the protein? How would this differ from the location of hydrophobic amino acids in a protein that is loose in the cytoplasm, such as an enzyme? Answer: Student answers will vary but should include the following. Hydrophobic interactions make it energetically favorable for nonpolar amino acids to be in the center of a protein in the cytoplasm, where they will interact with each other instead of with the watery cytoplasm of the cell. The inner layer of the cell membrane is composed of the fatty acid tails of the phospholipids, so it is nonpolar. Therefore, hydrophobic amino acids would tend to be located where they would contact the fatty acid tails in center of the cell membrane rather than the polar phosphate groups on the inner and outer sides of the membrane. Within the hydrocarbon portion of the membrane, nonpolar amino acids would be toward the outside of Page 18 of 19 OpenStax Microbiology Test Bank Chapter 7: Microbial Biochemistry the protein and polar amino acids may be inside in the case of a protein channel. For parts of the protein toward the outside of the membrane, which interact with the polar heads of the phospholipids and extend into the cell, polar amino acids would be predicted to be on the outside and nonpolar amino acids would be toward the inside of the folded protein. Difficulty: Difficult ASM Standard: N/A 81. People often think of fats as unhealthy and something that they should avoid. What are some reasons that fats are important in the human diet? Give at least three reasons. Answer: Student answers may vary but should include at least some of the following. Fats are important in building cell membranes. There are phospholipids forming the membrane bilayer and cholesterol within the membrane. Adipose (fat) tissue provides insulation, cushioning, and contouring. Fats are important in energy storage. Because fat is hydrophobic, it can be very tightly packed and takes up less space than glycogen (which associates with water molecules). Animals obtain energy by oxidizing organic molecules. Because fats are more reduced than carbohydrates or proteins, more energy can be extracted from them. Fats also serve additional purposes while storing energy, such as providing cushioning and insulation. Difficulty: Difficult ASM Standard: N/A 82. What are similarities between cholesterol and hopanoids? What types of organisms use them? What are some other molecules with similar functions? Answer: Student answers will vary but should include components of the following. Both cholesterol and hopanoids are used to stabilize the cell membrane. Hopanoids are found in prokaryotic cell membranes and cholesterol is found in eukaryotic cell membranes. Other molecules with similar functions are phytosterols, used by plants, and ergosterols, used by fungi. Difficulty: Moderate ASM Standard: N/A This file is copyright 2017, Rice University. All rights reserved. Page 19 of 19