Test Bank For The Molecules of Life, 1st Edition

Chapter 2—Atoms and Molecules: The Chemical Basis of Life MULTIPLE CHOICE 1. An organic compound differs from an inorganic compound in that an organic compound: a. contains carbon. b. contains two or more atoms. c. lacks valence electrons. d. lacks isotopes. e. is basic rather than acidic. ANS: A PTS: 1 REF: p. 27 OBJ: Bloom’s: Comprehension 2. An element is defined as a substance that: a. is composed of more than one kind of atom. b. is held together by covalent bonds. c. cannot be broken into simpler substances by chemical reactions. d. cannot burn. e. is soluble in both acid and base. ANS: C PTS: 1 REF: p. 27 OBJ: Bloom’s: Knowledge 3. Which of the following elements is NOT responsible for a significant portion of the mass of living organisms? a. O b. S c. N d. H e. C ANS: B PTS: 1 REF: p. 27 OBJ: Bloom’s: Comprehension 4. The particular type of element is determined by the number of: a. electrons b. protons c. neutrons d. valence electrons e. energy levels ANS: B PTS: 1 REF: p. 27 OBJ: Bloom’s: Knowledge 5. If atom X contains 14 protons, 13 electrons, and 12 neutrons, and atom Y contains 14 protons, 14 electrons, and 12 neutrons, then you conclude that: a. Y is an ion but X is not. b. X and Y are both ions. c. X and Y both have filled valence shells. d. X and Y are isotopes of the same element. e. X and Y are atoms of the same element. ANS: E PTS: 1 REF: p. 27 Chapter 2—Atoms and Molecules: The Chemical Basis of Life OBJ: Bloom’s: Application 16 6. An atom has six protons and eight neutrons. Its atomic mass is __________ atomic mass units. a. two b. four c. six d. eight e. fourteen ANS: E PTS: 1 REF: p. 29 OBJ: Bloom’s: Comprehension 7. The difference between a stable isotope and a radioisotope is that: a. the stable isotope emits radiation. b. the radioisotope emits radiation. c. the stable isotope emits light. d. the stable isotope absorbs radiation. e. the radioisotope has an unequal number of protons and electrons. ANS: B PTS: 1 REF: p. 29 OBJ: Bloom’s: Comprehension Figure 2-1 Use the figure below to answer the corresponding question(s). 8. The atomic mass of the atom identified as A in Figure 2-1 is: a. 2. b. 6. c. 8. d. 12. e. 18. ANS: D PTS: 1 REF: p. 29 OBJ: Bloom’s: Application REF: p. 29 OBJ: Bloom’s: Application 9. Figure 2-1 represents: a. two isotopes of the same element. b. two different elements. c. two different ions. d. an acid and a base. e. a cation and an anion. ANS: A PTS: 1 10. The difference between the two atoms in Figure 2-1 is: a. pH. b. the number of electrons. c. the number of protons. d. the number of neutrons. e. electrical charge. ANS: D PTS: 1 REF: p. 29 Chapter 2—Atoms and Molecules: The Chemical Basis of Life OBJ: Bloom’s: Application 17 11. Isotopes differ from each other with respect to the number of: a. protons only. b. electrons only. c. neutrons only. d. both protons and electrons. e. both neutrons and protons. ANS: C PTS: 1 REF: p. 29 OBJ: Bloom’s: Knowledge 12. Radioisotopes are used in all of the following scientific applications except: a. dating fossils. b. determining the sequence of genetic information in DNA. c. localization of a drug, such as marijuana. d. the treatment of cancer. e. measuring the pH of the blood. ANS: E PTS: 1 REF: p. 29-30 OBJ: Bloom’s: Comprehension 13. The chemical behavior of an atom is determined by most directly by the: a. atomic number. b. atomic weight. c. number of energy levels. d. number of valence electrons. e. number of neutrons. ANS: D PTS: 1 REF: p. 31 OBJ: Bloom’s: Comprehension 14. Which of the following statements is FALSE? a. The 1st principal energy level contains 1 orbital. b. The 2nd principal energy level contains 4 orbitals. c. The 1st principal energy level contains a maximum of 2 electrons. d. The 2nd energy level contains a maximum of 10 electrons. e. The 2nd energy level contains 1 spherical orbital and 3 dumbbell-shaped orbitals.. ANS: D PTS: 1 REF: p. 30 OBJ: Bloom’s: Comprehension 15. Chlorine has seven electrons in its valence shell. The number of electrons it must gain to complete its valence shell is: a. one. b. two. c. three. d. seven. e. eight. ANS: A PTS: 1 REF: p. 31 OBJ: Bloom’s: Application 16. Any chemical interaction between atoms: a. involves neutrons. b. may potentially involve any electron. c. involves protons. d. involves only valence electrons. e. involves only the nuclear subatomic particles. ANS: D PTS: 1 REF: p. 31 OBJ: Bloom’s: Comprehension Chapter 2—Atoms and Molecules: The Chemical Basis of Life 18 17. The representation H−O−H is known as: a. a structural formula. b. a simplest formula. c. a molecular formula. d. a Lewis structure. e. an orbital diagram. ANS: A PTS: 1 REF: p. 31 OBJ: Bloom’s: Knowledge 18. The molecular mass of C6H12O6 is 180 amu. 0.25 moles of this substance contain: a. 180 daltons. b. 45 g. c. 1.8 g. d. 45 daltons. e. 180 g. ANS: B PTS: 1 REF: p. 31-32 OBJ: Bloom’s: Application 19. How many molecules are present in one mole of C6H12O6? a. 1.7  10−10 molecules b. 1.3  1010 molecules c. 24 molecules d. 1.7  1022 molecules e. 6.02  1023 molecules ANS: E PTS: 1 REF: p. 32 OBJ: Bloom’s: Comprehension 20. Which of the following choices correctly identifies a reactant in the following chemical equation? CO2 + H2O  H2CO3 a. carbonic acid b. oxygen c. water d. sugar e. carbon monoxide ANS: C PTS: 1 REF: p. 32 OBJ: Bloom’s: Comprehension 21. In a chemical reaction, the product is: a. generally written on the right side of the equation. b. always in equilibrium with the reactants. c. the substance that is generated by the reaction. d. joined by an ionic bond only. e. generally written on the right side and is the substance generated by the reaction. ANS: E PTS: 1 REF: p. 32 OBJ: Bloom’s: Comprehension 22. When a chemical reaction is at equilibrium: a. the forward reaction is going faster. b. the reverse reaction is going faster. c. the forward and reverse reactions are proceeding at equal rates. d. the forward reaction stops. e. the reverse reaction stops. ANS: C PTS: 1 REF: p. 32 Chapter 2—Atoms and Molecules: The Chemical Basis of Life OBJ: Bloom’s: Knowledge 19 Figure 2-2 Use the figure below to answer the corresponding question(s). 23. Figure 2-2 represents: a. elemental helium. b. molecular hydrogen. c. molecular helium. d. a water molecule. e. molecular oxygen. ANS: B PTS: 1 REF: p. 33 OBJ: Bloom’s: Comprehension REF: p. 33 OBJ: Bloom’s: Comprehension 24. The type of bond illustrated in Figure 2-2 is: a. an ionic bond. b. a polar bond. c. a single covalent bond. d. a hydrogen bond. e. a double covalent bond. ANS: C PTS: 1 25. Which covalent bond involves only 2 electrons: a. single b. double c. triple d. single and double. e. single and triple. ANS: A PTS: 1 REF: p. 33 OBJ: Bloom’s: Knowledge 26. A covalent bond: a. forms only between identical atoms. b. involves a sharing of only one pair of electrons. c. is always polar. d. may be polar or nonpolar depending on the atoms involved. e. always forms between identical molecules. ANS: D PTS: 1 REF: p. 33-34 OBJ: Bloom’s: Comprehension 27. In a water molecule, because oxygen is more electronegative than hydrogen, the shared electrons are more commonly found around the __________ nucleus than the __________ nucleus. a. oxygen; hydrogen b. hydrogen; oxygen c. hydrogen; other hydrogen d. oxygen; nitrogen e. nitrogen; oxygen ANS: A PTS: 1 REF: p. 34 OBJ: Bloom’s: Comprehension Chapter 2—Atoms and Molecules: The Chemical Basis of Life 20 28. The covalent bond between a hydrogen atom and the oxygen atom in water is formed when: a. hydrogen gains an electron from oxygen. b. hydrogen and oxygen share an electron pair. c. hydrogen and oxygen both lose electrons from their outer shells. d. hydrogen and oxygen both gain electrons in their outer shells. e. hydrogen gains an electron from oxygen. ANS: B PTS: 1 REF: p. 34 OBJ: Bloom’s: Comprehension 29. Covalently bonded atoms with similar electronic negativities are: a. ionic. b. polar. c. nonpolar. d. partially positive. e. partially negative. ANS: C PTS: 1 REF: p. 34 OBJ: Bloom’s: Comprehension 30. An atom becomes a cation if: a. it gains one or more electron. b. it loses one or more electron. c. it shares electrons. d. one or more of its electrons changes energy levels. e. it emits radiation. ANS: B PTS: 1 REF: p. 34 OBJ: Bloom’s: Application 31. The difference between an electrically neutral atom and an ion is that: a. an ion has an unequal number of protons and electrons, while an atom has an equal number. b. an ion has an equal number of protons and electrons, while an atom has an unequal number. c. an atom has an unequal number of neutrons and protons, while an ion has an equal number. d. an atom has its electrons in orbitals, while an ion has its electrons in its nucleus. e. an atom must have an equal number of neutrons and electrons, while an ion does not. ANS: A PTS: 1 REF: p. 34 OBJ: Bloom’s: Comprehension 32. In the formation of common table salt, sodium and chlorine interact because: a. sodium and chlorine share a pair of electrons. b. sodium and chlorine share two pairs of electrons. c. chlorine donates seven electrons to sodium. d. there is no electron exchange. e. sodium donates one electron to chlorine. ANS: E PTS: 1 REF: p. 35 OBJ: Bloom’s: Comprehension Chapter 2—Atoms and Molecules: The Chemical Basis of Life 21 33. Table salt dissolves easily in water because: a. water can form covalent linkages with salt molecules. b. water can remove electrons from the chloride ion, which causes the latter to dissociate from the sodium and dissolve. c. water can add electrons to the sodium ion. d. water is polar and salt is nonpolar. Nonpolar compounds are more soluble in polar solvents because they are able to form strong covalent bonds that result in a breaking up of the molecule being dissolved. e. the partial positive charge of the hydrogens in the water molecule can associate with the negative charge of the chloride ion, and the partial negative charge of the oxygen of the water molecule can associate with the positive charge of the sodium atom. ANS: E PTS: 1 REF: p. 36 OBJ: Bloom’s: Comprehension 34. Which of the following atoms would most likely be involved in an ionic bond? a. hydrogen b. oxygen c. sodium d. hydrogen and oxygen. e. hydrogen and sodium. ANS: C PTS: 1 REF: p. 35 OBJ: Bloom’s: Comprehension 35. The process whereby water molecules surround ions during the process of dissolving is called: a. reduction. b. hydration. c. buffering. d. oxidation. e. vaporization. ANS: B PTS: 1 REF: p. 36 OBJ: Bloom’s: Knowledge 36. Which of the following statements concerning van der Waal interactions is FALSE: a. They are attractive forces. b. They are very strong. c. They involve transient regions of positive and negative charges. d. They form between nonpolar molecules. e. They operate over very short distances. ANS: B PTS: 1 REF: p. 36 OBJ: Bloom’s: Knowledge 37. Which component becomes oxidized in the following chemical reaction? 4 Fe + 3 O2 → 2 Fe2O3 a. water b. iron c. oxygen d. rust e. hydrogen ANS: B PTS: 1 REF: p. 37 Chapter 2—Atoms and Molecules: The Chemical Basis of Life OBJ: Bloom’s: Application 22 38. Which component is the oxidizing agent in the following chemical reaction? 4 Fe + 3 O2 → 2 Fe2O3 a. water b. iron c. oxygen d. rust e. hydrogen ANS: C PTS: 1 REF: p. 37 OBJ: Bloom’s: Application 39. The cohesiveness between water molecules is due largely to: a. hydrogen bonds. b. polar covalent bonds. c. nonpolar covalent bonds. d. ionic bonds. e. hydrophobic interactions. ANS: A PTS: 1 REF: p. 38 OBJ: Bloom’s: Knowledge 40. A stalk of celery is placed in a solution of blue colored dye. After one hour, the leaves have blue fluid in their veins. Which property of water is being demonstrated? a. adhesion and cohesion b. evaporation and cooling c. lower density as a solid than as a liquid d. high specific heat e. surface tension ANS: A PTS: 1 REF: p. 38 OBJ: Bloom’s: Application 41. Which characteristic of water molecules directly contributes to the remarkable “water walking” success of the aquatic insects pictured in the accompanying figure? a. b. c. d. e. hydrogen bonds capillary action nonpolar covalent bonds ionic bonds adhesive forces ANS: A PTS: 1 REF: p. 38 OBJ: Bloom’s: Comprehension 42. Which of the following statements is not correct? a. Water heats up and cools down very quickly. b. The amount of heat required to raise the temperature of 1 g of water 1 C is one calorie. c. Due to hydrogen bonds, water has a high surface tension. d. Large bodies of water have relatively constant temperatures. e. When one gram of water evaporates, it removes heat. ANS: A PTS: 1 REF: p. 38-40 Chapter 2—Atoms and Molecules: The Chemical Basis of Life OBJ: Bloom’s: Comprehension 23 43. It takes 1 calorie of heat to raise the temperature of 1 gram of water 1 degree Celsius at sea level. This is referred to as the __________ of water. a. heat of fusion b. heat of vaporization c. specific heat d. heat of transformation e. heat of homeostasis ANS: C PTS: 1 REF: p. 40 OBJ: Bloom’s: Knowledge 44. Which property of water enables living things to survive in ponds covered with ice? a. high heat of vaporization b. high specific heat c. degree of surface tension d. cohesion e. greatest density at 4oC ANS: E PTS: 1 REF: p. 40 OBJ: Bloom’s: Comprehension 45. Evaporative cooling is a process whereby __________ moving __________ molecules vaporize, thus __________ large amounts of heat. a. slow; water; adding b. fast; water; removing c. slow; oxygen; adding d. fast; oxygen; removing e. fast; carbon dioxide; removing ANS: B PTS: 1 REF: p. 40 OBJ: Bloom’s: Comprehension REF: p. 40 OBJ: Bloom’s: Knowledge 46. At what temperature is water most dense? a. 0 degrees Celsius b. 1 degree Celsius c. 4 degrees Celsius d. 10 degrees Celsius e. 100 degrees Celsius ANS: C PTS: 1 47. In a mixture, which would be present in the least amount? a. solvent b. solute c. water d. both solvent and solute e. both solvent and water ANS: B PTS: 1 REF: p. 36 Chapter 2—Atoms and Molecules: The Chemical Basis of Life OBJ: Bloom’s: Knowledge 24 48. This characteristic of a molecule determines the ability of hydrogen bonds to form between it and hydrogen: a. A nonpolar atom. b. An atom with a partial positive charge. c. An atom with a partial negative charge. d. A hydrophobic molecule. e. An atom with a filled valence shell. ANS: C PTS: 1 REF: p. 36 OBJ: Bloom’s: Comprehension 49. Which characteristic of water makes the existence of pH possible? a. ionization b. polarity c. adhesion d. cohesion e. hydrophobicity ANS: A PTS: 1 REF: p. 40 OBJ: Bloom’s: Comprehension 50. A pH of 4 is __________ times more __________ than a pH of 7. a. 3; basic b. 3; acidic c. 1000; neutral d. 1000; basic e. 1000; acidic ANS: E PTS: 1 REF: p. 41 OBJ: Bloom’s: Application 51. What is the OH− concentration of a solution having a pH of 2? a. 1  10−12 b. 1  10−10 c. 1  10−7 d. 1  10−2 e. 1  10−1 ANS: A PTS: 1 REF: p. 41 OBJ: Bloom’s: Application 52. When a small amount of hydrochloric acid (HCl) is added to a solution of Na2HPO4, the pH of the solution does not change markedly. The pH also does not change drastically when a small amount of sodium hydroxide (NaOH) is added to this same solution. Based on these observations, the compound Na2HPO4 is: a. able to donate hydrogen atoms to HCl. b. able to remove hydrogen ions from the OH− of NaOH. c. acting as a buffer. d. an enzyme facilitating the reaction between HCl and NaOH. e. acting as a solvent. ANS: C PTS: 1 REF: p. 42 Chapter 2—Atoms and Molecules: The Chemical Basis of Life OBJ: Bloom’s: Application 25 53. A salt is a compound in which the hydrogen ion of __________ is replaced by some other cation. a. a base b. an acid c. an anion d. a hydroxide ion e. water ANS: B PTS: 1 REF: p. 42 OBJ: Bloom’s: Knowledge 54. A solution having a pH of 6 would: a. have equal concentrations of hydrogen ions and hydroxide ions. b. have a higher concentrations of hydroxide ions than hydrogen ions. c. be slightly acidic. d. be slightly basic. e. be neutral. ANS: C PTS: 1 REF: p. 41 OBJ: Bloom’s: Knowledge 55. Identify the chemical(s) that act(s) as a buffer in human blood: a. bicarbonate b. hydrogen ions c. carbon dioxide d. water e. hydroxide ions ANS: A PTS: 1 REF: p. 42 OBJ: Bloom’s: Knowledge 56. Identify the hydrogen ion concentration that represents the lowest pH from the following list: a. 1  10−3 b. 1  10−4 c. 1  10−7 d. 1  10−11 e. 1  10−14 ANS: A PTS: 1 REF: p. 41 OBJ: Bloom’s: Knowledge 57. Which of the following has a pH closest to that of human blood? a. beer b. coffee c. rain water d. sea water e. oven cleaner ANS: D PTS: 1 REF: p. 41 OBJ: Bloom’s: Knowledge 58. Which of the following would most likely form electrolytes in water? a. glucose b. ethanol c. an organic compound d. an inorganic compound e. a nonionic compound ANS: D PTS: 1 REF: p. 42 Chapter 2—Atoms and Molecules: The Chemical Basis of Life OBJ: Bloom’s: Knowledge 26 SHORT ANSWER 1. List the four elements that account for over 90% of the mass of living organisms and identify an important biological function of each element. ANS: Some examples from Table 2-1: Oxygen is required for cellular respiration, carbon forms the backbone of organic molecules, hydrogen is involved in some energy transfers, and nitrogen is a component of proteins and nucleic acids. PTS: 1 REF: p. 27 OBJ: Bloom’s: Knowledge 2. Explain how the number of valence electrons is related to the chemical properties of an atom. Use two specific examples in your explanation. ANS: Atoms having filled valence shells (e.g., helium and neon) are stable and unreactive; atoms having unfilled valence shells (e.g., chlorine and sodium) are unstable and reactive. PTS: 1 REF: p. 31 OBJ: Bloom’s: Comprehension 3. Compare and contrast the formation, properties, and characteristics of covalent and ionic bonds. ANS: Both covalent and ionic bonds result in each atom having a filled valence shell. Covalent bonds are formed via the sharing of electrons between neutral atoms; the resulting molecule is electrically neutral but can be polar or nonpolar. Ionic bonds are formed via the transfer of electrons; in the process ions are formed, and the resulting molecule is held together via the electrical attraction between those positive and negative ions. Unlike atoms joined by a covalent bond, atoms joined by an ionic bond tend to dissociate into their respective ions when placed in water. PTS: 1 REF: p. 34-35 OBJ: Bloom’s: Analysis 4. Diagram and carefully label two water molecules using a ball-and-stick model. Then use this diagram to demonstrate how hydrogen bonds form between them. ANS: The diagram should resemble Fig. 2-13 except only two water molecules are shown. Hydrogen bonds form as a result of the attraction between the partial positive charge of a hydrogen atom with the partial negative charge of the oxygen atom PTS: 1 REF: p. 38 OBJ: Bloom’s: Analysis MODIFIED TRUE/FALSE 1. An inorganic compound is one that contains carbon. __________________ ANS: F, organic PTS: 1 REF: p. 27 OBJ: Bloom’s: Knowledge Chapter 2—Atoms and Molecules: The Chemical Basis of Life 27 2. The atomic mass determines the type of element. __________________ ANS: F, number PTS: 1 REF: p. 28 OBJ: Bloom’s: Knowledge 3. An atom having a filled valence shell is stable and unreactive. __________________ ANS: T OBJ: Bloom’s: Knowledge PTS: 1 REF: p. 31 4. When atoms react to form an ionic bond, electrons are shared between those atoms. __________________ ANS: F, transferred PTS: 1 REF: p. 35 OBJ: Bloom’s: Knowledge 5. The tetrahedron shape of a methane molecule is the result of orbital hybridization. __________________ ANS: T OBJ: Bloom’s: Knowledge PTS: 1 REF: p. 34 6. An example of an anion is K+. __________________ ANS: F, a cation PTS: 1 REF: p. 34 OBJ: Bloom’s: Knowledge 7. Oxidation occurs when an atom gains one or more electrons. __________________ ANS: F, loses PTS: 1 REF: p. 37 OBJ: Bloom’s: Knowledge 8. Specific heat refers to the amount of energy required to change 1 gram of a substance from the liquid phase to the vapor phase. __________________ ANS: F, Heat of vaporization PTS: 1 REF: p. 39 OBJ: Bloom’s: Knowledge 9. Water is most dense at 4 C. __________________ ANS: T OBJ: Bloom’s: Knowledge PTS: 1 Chapter 2—Atoms and Molecules: The Chemical Basis of Life REF: p. 40 28 10. A solution having a pH of 8 is slightly acidic. __________________ ANS: F, basic PTS: 1 REF: p. 41 OBJ: Bloom’s: Knowledge 11. A substance that is resistant to changes in pH is called a buffer. __________________ ANS: T NOT: Bloom’s: Knowledge PTS: 1 REF: p. 42 MATCHING Match the type of bond or interaction with its description. a. hydrogen bond c. ionic bond b. van de Waals interaction d. covalent bond 1. 2. 3. 4. 5. 6. Strong attractive force resulting from the transfer of electrons between atoms Strong attractive force resulting from the sharing of electrons between atoms Weak attractive force joining a hydrogen atom with an electronegative atom such as oxygen In a structural formula this is represented by a straight line Very weak attractive force joining nonpolar molecules Holds adjacent water molecules together 1. 2. 3. 4. 5. 6. ANS: C ANS: D ANS: A ANS: D ANS: B ANS: A PTS: PTS: PTS: PTS: PTS: PTS: 1 1 1 1 1 1 Match the term with its description. a. adhesion b. cohesion REF: REF: REF: REF: REF: REF: p. 35 p. 32 p. 36 p. 33 p. 36 p. 37 OBJ: OBJ: OBJ: OBJ: OBJ: OBJ: Bloom’s: Knowledge Bloom’s: Knowledge Bloom’s: Knowledge Bloom’s: Knowledge Bloom’s: Knowledge Bloom’s: Comprehension c. surface tension d. capillary action 7. Sticking together of like molecules 8. Directly responsible for the ability of certain insects to walk on water 9. Responsible for the ability of water molecules to move in the microscopic spaces between soil particles 10. Sticking together of unlike molecules 11. Tendency of water to move in narrow tubes 7. 8. 9. 10. 11. ANS: B ANS: C ANS: D ANS: A ANS: D PTS: PTS: PTS: PTS: PTS: 1 1 1 1 1 REF: REF: REF: REF: REF: p. 38 p. 38 p. 38 p. 38 p. 38 Chapter 2—Atoms and Molecules: The Chemical Basis of Life OBJ: OBJ: OBJ: OBJ: OBJ: Bloom’s: Knowledge Bloom’s: Knowledge Bloom’s: Knowledge Bloom’s: Knowledge Bloom’s: Knowledge 29 ESSAY 1. As a researcher, you are charged with determining the side effects of a new drug. From previous observations, you suspect that this drug reduces the rate of DNA production (replication) within skin cells of patients using the drug. With the following materials, design an experiment that would answer your questions about the effect of the drug on DNA production. You know that: DNA contains phosphate groups. You have: radioactive isotopes of phosphate (32P), skin cell cultures from various patients, the drug in question, and a device that measures radioactivity. ANS: Concepts to Consider: Construction of an appropriate experiment with appropriate controls; use of the radioisotope to label DNA; isolation of the DNA using an unspecified technique; measuring radioactivity of the isolated DNA; comparing the treatment and control groups; making a conclusion. PTS: 1 REF: p. 29 TOP: Discussion or Thought Questions OBJ: Bloom’s: Synthesis 2. The hydrogen bonds of water play an important role in the ability of animals to regulate their body temperature. Explain how this occurs. ANS: Concepts to Consider: Transfer of energy to the hydrogen bonds; excess body heat is transferred to hydrogen bonds of water; heat is removed when water vaporizes at the body surface of the animal. PTS: 1 REF: p. 40 TOP: Discussion or Thought Questions OBJ: Bloom’s: Comprehension 3. Explain the role of carbon dioxide in maintaining blood pH levels. ANS: Concepts to Consider: Buffering capacity; reversible reactions; maintenance of equilibrium. PTS: 1 REF: p. 42 TOP: Discussion or Thought Questions OBJ: Bloom’s: Comprehension Chapter 2—Atoms and Molecules: The Chemical Basis of Life 30