Fundamentals of Anatomy & Physiology, 9/E Frederic H. Martini, solutions manual and test bank
Fundamentals of Anatomy and Physiology, 9e (Martini)
Chapter 2 The Chemical Level of Organization
Multiple-Choice Questions
1) The smallest stable units of matter are
A) atoms.
B) molecules.
C) protons.
D) neutrons.
E) electrons.
Answer: A
Learning Outcome: 2-1
Bloom's Taxonomy: Knowledge
2) The "atomic number" of an atom is determined by the number of ________ it has.
A) electrons
B) protons
C) neutrons
D) protons + neutrons
E) protons + electrons
Answer: B
Learning Outcome: 2-1
Bloom's Taxonomy: Knowledge
3) The "atomic weight" of an atom reflects the average number of
A) protons.
B) neutrons.
C) electrons.
D) protons + neutrons.
E) protons + neutrons + electrons.
Answer: E
Learning Outcome: 2-1
Bloom's Taxonomy: Knowledge
4) One mole of any element
A) has the same mass.
B) has the same weight.
C) has the same number of atoms.
D) has the same number of electrons.
E) All of the answers are correct.
Answer: C
Learning Outcome: 2-1
Bloom's Taxonomy: Knowledge
5) The nucleus of an atom consists of
A) electrons.
B) protons.
C) neutrons.
D) protons + neutrons.
E) protons + electrons.
Answer: D
Learning Outcome: 2-1
Bloom's Taxonomy: Knowledge
6) Isotopes of an element differ in the number of
A) protons in the nucleus.
B) electrons in the nucleus.
C) neutrons in the nucleus.
D) electron clouds.
E) electrons in energy shells.
Answer: C
Learning Outcome: 2-1
Bloom's Taxonomy: Knowledge
7) The mass number represents the number of
A) protons in an atom.
B) electrons in an ion.
C) neutrons in an atom.
D) protons + neutrons.
E) neutrons + electrons.
Answer: D
Learning Outcome: 2-1
Bloom's Taxonomy: Knowledge
8) The innermost electron shell in an atom holds up to ________ electrons.
A) 1
B) 2
C) 4
D) 6
E) 8
Answer: B
Learning Outcome: 2-1
Bloom's Taxonomy: Knowledge
9) Radioisotopes have unstable
A) ions.
B) nuclei.
C) isotopes.
D) electron clouds.
E) protons.
Answer: B
Learning Outcome: 2-1
Bloom's Taxonomy: Knowledge
10) By weight, which element is the most plentiful in the human body?
A) sulfur
B) sodium
C) oxygen
D) potassium
E) carbon
Answer: C
Learning Outcome: 2-1
Bloom's Taxonomy: Knowledge
11) Indicate which of these lists contains only trace elements.
A) sulfur, chlorine, oxygen
B) selenium, hydrogen, calcium
C) boron, oxygen, carbon
D) silicon, fluorine, tin
E) cobalt, calcium, sodium
Answer: D
Learning Outcome: 2-1
Bloom's Taxonomy: Knowledge
12) The atomic number represents the number of
A) electrons in an atom.
B) protons in an atom.
C) neutrons in an atom.
D) protons and neutrons in an atom.
E) chemical bonds the atom may form.
Answer: B
Learning Outcome: 2-1
Bloom's Taxonomy: Knowledge
13) Helium (He) has an atomic number of 2. It is chemically stable because it
A) is neutral in electrical charge.
B) readily ionizes to react with other atoms.
C) has a full outer electron shell.
D) will form a covalent bond with another He atom.
E) lacks electrons, thus the He atom is stable.
Answer: C
Learning Outcome: 2-1
Bloom's Taxonomy: Comprehension
14) Which element commonly has only a proton as its nucleus?
A) helium
B) neon
C) argon
D) hydrogen
E) carbon
Answer: D
Learning Outcome: 2-1
Bloom's Taxonomy: Comprehension
15) By weight, which element is the second most abundant in the human body?
A) oxygen
B) carbon
C) hydrogen
D) nitrogen
E) calcium
Answer: B
Learning Outcome: 2-1
Bloom's Taxonomy: Comprehension
16) The mass of an atom is largely determined by the number of ________ it has.
A) electrons
B) protons
C) neutrons
D) protons + neutrons
E) protons + electrons
Answer: D
Learning Outcome: 2-1
Bloom's Taxonomy: Comprehension
17) If an isotope of oxygen has 8 protons, 10 neutrons, and 8 electrons, its mass number is
A) 26.
B) 16.
C) 18.
D) 8.
E) 12.
Answer: C
Learning Outcome: 2-1
Bloom's Taxonomy: Application
18) If an element is composed of atoms with an atomic number of 6 and a mass number of 14, then a neutral atom of this element contains
A) 6 protons.
B) 8 electrons.
C) 8 neutrons.
D) 6 protons and 8 electrons.
E) 6 protons and 8 neurons.
Answer: E
Learning Outcome: 2-1
Bloom's Taxonomy: Application
19) The molecule NO is known as
A) nitric oxide.
B) noxious oxide.
C) noxious oxygen.
D) nitric oxygen.
E) nitrous oxide.
Answer: A
Learning Outcome: 2-2
Bloom's Taxonomy: Knowledge
20) The molecule CO2 is known as
A) carbonized oxygen.
B) carbonated oxygen.
C) carbon monoxide.
D) carbon oxide.
E) carbon dioxide.
Answer: E
Learning Outcome: 2-2
Bloom's Taxonomy: Knowledge
21) The molecule H2 is known as
A) hydrohydrogen.
B) hydrogen.
C) hydroxide.
D) helium.
E) semi-water.
Answer: B
Learning Outcome: 2-2
Bloom's Taxonomy: Knowledge
22) When electrons are transferred from one atom to another, and the two atoms unite as a result of the opposite charges,
A) an ion is formed.
B) a molecule is formed.
C) a hydrogen bond is formed.
D) an ionic bond is formed.
E) a covalent bond is formed.
Answer: D
Learning Outcome: 2-2
Bloom's Taxonomy: Knowledge
23) Magnesium atoms have two electrons in the outermost shell. As a result, you would expect magnesium to form ions with a charge of
A) +1.
B) +2.
C) -1.
D) -2.
E) either +2 or -2.
Answer: B
Learning Outcome: 2-2
Bloom's Taxonomy: Comprehension
24) Which of the following statements about hydrogen bonds is false?
A) Hydrogen bonds are strong attractive forces between hydrogen atoms and negatively charged atoms.
B) Hydrogen bonds can occur within a single molecule.
C) Hydrogen bonds can form between neighboring molecules.
D) Hydrogen bonds are important for holding large molecules together.
E) Hydrogen bonds are responsible for many of the properties of water.
Answer: A
Learning Outcome: 2-2
Bloom's Taxonomy: Knowledge
25) The molecule O2 is known as
A) oxide.
B) oxygen.
C) organic.
D) oxate
E) a salt
Answer: B
Learning Outcome: 2-2
Bloom's Taxonomy: Knowledge
26) H2O is an example of a(n)
A) ionic formula.
B) glucose molecule.
C) compound.
D) ion.
E) covalent formula.
Answer: C
Learning Outcome: 2-2
Bloom's Taxonomy: Knowledge
27) Which of the following is not a cation?
A) Na+
B) Cl-
C) K+
D) Ca2+
E) Mg2+
Answer: B
Learning Outcome: 2-2
Bloom's Taxonomy: Knowledge
28) A dust particle floating on a water surface illustrates
A) surface tension.
B) chemical tension.
C) static electricity.
D) heat capacity.
E) hydrophilic attraction.
Answer: A
Learning Outcome: 2-2
Bloom's Taxonomy: Knowledge
29) In an aqueous solution, cations are attracted toward
A) sodium.
B) salt.
C) buffers.
D) anions.
E) hydrogen ions.
Answer: D
Learning Outcome: 2-2
Bloom's Taxonomy: Knowledge
30) In an aqueous solution, sodium ions would move toward
A) a negative terminal.
B) a positive terminal.
C) a pH terminal.
D) an organic terminal.
E) the bottom.
Answer: A
Learning Outcome: 2-2
Bloom's Taxonomy: Knowledge
31) The chemical behavior of an atom is determined by
A) the number of protons.
B) the number of neutrons.
C) the outermost electron shell.
D) the size of the atom.
E) the mass of the nucleus.
Answer: C
Learning Outcome: 2-2
Bloom's Taxonomy: Knowledge
32) Ions with a + charge are called
A) cations.
B) anions.
C) radicals.
D) positrons.
E) isotopes.
Answer: A
Learning Outcome: 2-2
Bloom's Taxonomy: Knowledge
33) The weakest bond between two atoms is the ________ bond.
A) ionic
B) covalent
C) polar
D) nonpolar
E) hydrogen
Answer: E
Learning Outcome: 2-2
Bloom's Taxonomy: Knowledge
34) When atoms complete their outer electron shell by sharing electrons, they form
A) ionic bonds.
B) covalent bonds.
C) hydrogen bonds.
D) anions.
E) cations.
Answer: B
Learning Outcome: 2-2
Bloom's Taxonomy: Knowledge
35) Ionic bonds are formed when
A) atoms share electrons.
B) an electron or electrons are completely transferred from one atom to another.
C) a pair of electrons is shared unequally by two atoms.
D) hydrogen forms bonds with negatively charged atoms.
E) two or more atoms lose electrons at the same time.
Answer: B
Learning Outcome: 2-2
Bloom's Taxonomy: Knowledge
36) If a pair of electrons is unequally shared between two atoms, a(n) ________ occurs.
A) single covalent bond
B) double covalent bond
C) triple covalent bond
D) polar covalent bond
E) hydrogen bond
Answer: D
Learning Outcome: 2-2
Bloom's Taxonomy: Knowledge
37) Elements that have atoms with full outer shells of electrons
A) will form many compounds.
B) will normally form anions.
C) will normally form cations.
D) frequently form hydrogen bonds.
E) are inert gases.
Answer: E
Learning Outcome: 2-2
Bloom's Taxonomy: Knowledge
38) Ions in an ionic molecule are held together due to
A) the sharing of electrons.
B) the attraction of opposite electrical charges.
C) each electron orbiting all of the ions in the molecule.
D) the presence of water molecules.
E) the attraction of similar charges of the ions' protons.
Answer: B
Learning Outcome: 2-2
Bloom's Taxonomy: Knowledge
39) An unequal sharing of electrons results in what type of chemical bonds?
A) polar covalent
B) covalent
C) ionic
D) hydrogen
E) peptide
Answer: A
Learning Outcome: 2-2
Bloom's Taxonomy: Knowledge
40) Sodium (Na) has an atomic number of 11. How many electrons are in the outer electron shell of a neutral sodium atom?
A) 1
B) 2
C) 3
D) 4
E) 8
Answer: A
Learning Outcome: 2-2
Bloom's Taxonomy: Comprehension
41) Oxygen (atomic number 8) requires how many additional electrons to fill its outer electron shell?
A) 1
B) 2
C) 4
D) 6
E) 8
Answer: B
Learning Outcome: 2-2
Bloom's Taxonomy: Comprehension
42) The formula for methane gas is CH4. What does the formula 4CH4 represent?
A) a molecule with 4 carbon atoms
B) a molecule with 4 carbon atoms and 16 hydrogen atoms
C) 4 molecules, each containing a carbon and a hydrogen atom
D) 4 molecules, each containing a carbon atom and 4 hydrogen atoms
E) an inorganic compound with ionic bonds
Answer: D
Learning Outcome: 2-2
Bloom's Taxonomy: Comprehension
43) In an ionic bond, the electron donor is the ________, whereas the electron acceptor is the ________.
A) acid, base
B) salt, ion
C) anion, cation
D) base, acid
E) cation, anion
Answer: E
Learning Outcome: 2-2
Bloom's Taxonomy: Comprehension
44) In a molecule of nitrogen, three pairs of electrons are shared by two nitrogen atoms. The type of bond that is formed is an example of a(n)
A) single trivalent bond.
B) double divalent bond.
C) triple covalent bond.
D) polar covalent bond.
E) hydrogen bond.
Answer: C
Learning Outcome: 2-2
Bloom's Taxonomy: Comprehension
45) In chemical notation, the symbol Ca2+ means ________.
A) two calcium atoms
B) a calcium ion that has lost two electrons
C) a calcium ion that has gained two protons
D) a calcium ion that has gained two electrons
E) a calcium ion that has lost two protons
Answer: B
Learning Outcome: 2-2
Bloom's Taxonomy: Comprehension
46) Magnesium atoms have two electrons in the outermost shell and chlorine atoms have seven. The compound magnesium chloride would contain
A) 1 magnesium and 1 chlorine.
B) 1 magnesium and 2 chlorine.
C) 2 magnesium and 1 chlorine.
D) 2 magnesium and 7 chlorine.
E) impossible to tell without more information
Answer: B
Learning Outcome: 2-2
Bloom's Taxonomy: Application
47) AB → A + B is to decomposition as A + B → AB is to
A) exchange.
B) synthesis.
C) combustion.
D) replacement.
E) metabolism.
Answer: B
Learning Outcome: 2-3
Bloom's Taxonomy: Knowledge
48) The reaction N2 + 3 H2 → 2 NH3 is an example of a(n)
A) exchange reaction.
B) decomposition reaction.
C) synthesis reaction.
D) enzyme reaction.
E) metabolic reaction.
Answer: C
Learning Outcome: 2-3
Bloom's Taxonomy: Comprehension
49) The reaction A + B + energy → AB is an example of a(n)
A) exergonic reaction.
B) endergonic reaction.
C) equilibrium reaction.
D) decomposition reaction.
E) exchange reaction.
Answer: B
Learning Outcome: 2-3
Bloom's Taxonomy: Knowledge
50) In hydrolysis reactions, compounds react with
A) hydrogen, causing decomposition.
B) glucose, causing decomposition.
C) water, causing decomposition.
D) carbon, causing decomposition.
E) water, causing synthesis.
Answer: C
Learning Outcome: 2-3
Bloom's Taxonomy: Knowledge
51) Which one of the following statements is not correct about the reaction H2 + Cl2 → 2 HCl?
A) H2 and Cl2 are the reactants.
B) HCl is the product.
C) One molecule of hydrogen contains two atoms.
D) Two molecules of HCl are formed in the reaction.
E) This reaction is easily reversible.
Answer: E
Learning Outcome: 2-3
Bloom's Taxonomy: Comprehension
52) In dehydration synthesis reactions, compounds
A) lose water molecules.
B) gain water molecules.
C) convert water molecules to hydrogen and oxygen.
D) convert hydrogen and oxygen to water.
E) gain electrons.
Answer: A
Learning Outcome: 2-3
Bloom's Taxonomy: Comprehension
53) In the reaction listed below, what coefficient needs to be added to balance the equation?
6 CO2 + 6 H2O → C6H12O6 + ________ O2
A) 2
B) 4
C) 6
D) 8
E) 10
Answer: C
Learning Outcome: 2-3
Bloom's Taxonomy: Application
54) Chemical reactions that yield energy, such as heat, are said to be
A) endergonic.
B) activated.
C) exergonic.
D) neutral.
E) thermonuclear.
Answer: C
Learning Outcome: 2-4
Bloom's Taxonomy: Knowledge
55) All of the following are true concerning enzymes, except that they
A) are proteins.
B) function as biological catalysts.
C) lower the activation energy required for a reaction.
D) affect only the rate of a chemical reaction.
E) are consumed during the reaction.
Answer: E
Learning Outcome: 2-4
Bloom's Taxonomy: Knowledge
56) Compounds that can be synthesized or broken down by chemical reactions inside the body are called
A) inorganic compounds.
B) organic compounds.
C) nutrients.
D) metabolites.
E) enzymes.
Answer: D
Learning Outcome: 2-5
Bloom's Taxonomy: Knowledge
57) Each of the following is an example of an inorganic compound, except
A) water.
B) acids.
C) bases.
D) salts.
E) carbohydrates.
Answer: E
Learning Outcome: 2-5
Bloom's Taxonomy: Knowledge
58) Identify which of the following is both an anion and a compound:
A) Na+
B) Cl-
C) K+
D) HCO3-
E) NaCl
Answer: D
Learning Outcome: 2-5
Bloom's Taxonomy: Knowledge
59) Nonpolar organic molecules are good examples of
A) electrolytes.
B) molecules that will dissociate when placed into water.
C) hydrophobic compounds.
D) hydrophilic compounds.
E) solutes.
Answer: C
Learning Outcome: 2-6
Bloom's Taxonomy: Knowledge
60) During ionization, water molecules disrupt the ionic bonds of a salt to produce a mixture of ions. These ions can carry a current and so are called
A) cations.
B) anions.
C) acids.
D) electrolytes.
E) counterions.
Answer: D
Learning Outcome: 2-6
Bloom's Taxonomy: Knowledge
61) Oppositely charged ions in solution are prevented from combining by
A) heat capacity of water.
B) hydration spheres.
C) water's nonpolar nature.
D) free radicals.
E) hydrogen bonding.
Answer: B
Learning Outcome: 2-6
Bloom's Taxonomy: Knowledge
62) An example of an inorganic substance is
A) fructose.
B) water.
C) glycerol.
D) carbon dioxide.
E) water and carbon dioxide.
Answer: E
Learning Outcome: 2-6
Bloom's Taxonomy: Knowledge
63) Hydrophilic molecules readily associate with
A) lipid molecules.
B) hydrophobic molecules.
C) water molecules.
D) acids.
E) salts.
Answer: C
Learning Outcome: 2-6
Bloom's Taxonomy: Knowledge
64) Which of the following statements about water is not correct?
A) It is composed of polar molecules.
B) It is responsible for much of the mass of the human body.
C) It has a relatively low heat capacity.
D) It can dissolve many substances.
E) It contains hydrogen bonds.
Answer: C
Learning Outcome: 2-6
Bloom's Taxonomy: Knowledge
65) Which property of water helps keeps body temperature stabilized?
A) kinetic energy
B) lubrication
C) surface tension
D) reactivity
E) thermal inertia
Answer: E
Learning Outcome: 2-6
Bloom's Taxonomy: Knowledge
66) Of the list below, which has the highest concentration of hydroxide ions?
A) pH 1
B) pH 14
C) pH 7
D) pH 10
E) pH 2
Answer: B
Learning Outcome: 2-7
Bloom's Taxonomy: Knowledge
67) Which pH is closest to normal body pH?
A) pH 7
B) pH 8
C) pH 4
D) pH 3
E) pH 2
Answer: A
Learning Outcome: 2-7
Bloom's Taxonomy: Knowledge
68) A(n) ________ removes hydrogen ions and a(n) ________ releases hydrogen ions.
A) acid; base
B) base; acid
C) compound; element
D) element; compound
E) molecule; acid
Answer: B
Learning Outcome: 2-7
Bloom's Taxonomy: Knowledge
69) An excess of hydrogen ions in the body fluids can have fatal results because this can
A) break chemical bonds.
B) change the shape of large complex molecules, rendering them nonfunctional.
C) disrupt tissue functions.
D) change body fluid pH.
E) All of the answers are correct.
Answer: E
Learning Outcome: 2-7
Bloom's Taxonomy: Knowledge
70) A solution containing equal numbers of hydrogen ions and hydroxide ions is
A) acidic.
B) basic.
C) neutral.
D) alkaline.
E) in equilibrium.
Answer: C
Learning Outcome: 2-7
Bloom's Taxonomy: Knowledge
71) The chemical notation that indicates concentration is represented as
A) ().
B) <>.
C) [ ].
D) {}.
E) ||.
Answer: C
Learning Outcome: 2-7
Bloom's Taxonomy: Knowledge
72) If a substance has a pH that is greater than 7, it is
A) neutral.
B) acidic.
C) alkaline.
D) a buffer.
E) a salt.
Answer: C
Learning Outcome: 2-7
Bloom's Taxonomy: Knowledge
73) Which pH of the following is the most acidic?
A) pH 2
B) pH 6
C) pH 4
D) pH 3
E) pH 1
Answer: E
Learning Outcome: 2-7
Bloom's Taxonomy: Knowledge
74) Which pH of the following is the least acidic?
A) pH 2
B) pH 6
C) pH 4
D) pH 3
E) pH 1
Answer: E
Learning Outcome: 2-7
Bloom's Taxonomy: Knowledge
75) An important buffer in body fluids is
A) NaCl.
B) NaOH.
C) HCl.
D) NaHCO3.
E) H2O.
Answer: D
Learning Outcome: 2-7
Bloom's Taxonomy: Knowledge
76) Which of the following substances would be most acidic?
A) lemon juice, pH = 2
B) urine, pH = 6
C) tomato juice, pH = 4
D) white wine, pH = 3
E) stomach secretions, pH = 1
Answer: E
Learning Outcome: 2-7
Bloom's Taxonomy: Comprehension
77) Of the following choices, the pH of the least acidic solution is
A) 6.0.
B) 4.5.
C) 2.3.
D) 1.0.
E) 12.0.
Answer: E
Learning Outcome: 2-7
Bloom's Taxonomy: Comprehension
78) Which has the greater concentration of hydrogen ions, a substance with a pH of 5 or a substance with a pH of 4?
A) A pH of 4 is greater.
B) A pH of 5 is greater.
C) They are both equal; 4 and 5 are relative values.
D) pH 9, if you mixed the solutions.
E) There is not enough information to determine.
Answer: A
Learning Outcome: 2-7
Bloom's Taxonomy: Comprehension
79) In the body, inorganic compounds
A) can serve as buffers.
B) can make up proteins.
C) are made from organic compounds.
D) are structural components of cells.
E) are metabolized for cellular energy.
Answer: A
Learning Outcome: 2-8
Bloom's Taxonomy: Knowledge
80) When placed in water, an inorganic compound dissociates 99 percent, forming hydrogen ions and anions. This compound would be
A) a strong base.
B) a weak base.
C) a strong acid.
D) a weak acid.
E) a salt.
Answer: C
Learning Outcome: 2-8
Bloom's Taxonomy: Comprehension
81) When a small amount of HCl or NaOH is added to a solution of Na2HPO4, the pH of the solution barely changes. Based on these observations, all of the following are true concerning the compound Na2HPO4, except
A) Na2HPO4 is able to accept extra hydrogen ions from the HCl.
B) Na2HPO4 is able to donate hydrogen ions to the OH- from NaOH.
C) Na2HPO4 adsorbs excess H+ and OH- directly onto the surface of its crystalline structure.
D) Na2HPO4 is a salt formed from reacting a strong base with a weak acid.
E) Na2HPO4 acts as a buffer.
Answer: C
Learning Outcome: 2-8
Bloom's Taxonomy: Comprehension
82) Carbohydrates, lipids, and proteins are classified as
A) organic molecules.
B) inorganic molecules.
C) acids.
D) salts.
E) bases.
Answer: A
Learning Outcome: 2-9
Bloom's Taxonomy: Knowledge
83) A functional group is best described as reoccurring clusters of
A) elements that occur in a salt.
B) atoms that greatly influence the chemical properties of molecules they are part of.
C) atoms that function in the body.
D) elements that form at high pH.
E) amino acids in a globular protein.
Answer: B
Learning Outcome: 2-9
Bloom's Taxonomy: Knowledge
84) Artificial sweeteners
A) are naturally similar to sugars.
B) are always some form of carbohydrate.
C) are usually not broken down by the body.
D) are inorganic sugar substitutes.
E) provide the same number of calories as an equivalent amount of sucrose.
Answer: C
Learning Outcome: 2-9
Bloom's Taxonomy: Knowledge
85) Fructose is
A) a hexose.
B) an isomer of glucose.
C) found in male reproductive fluids.
D) a carbohydrate.
E) All of the answers are correct.
Answer: E
Learning Outcome: 2-9
Bloom's Taxonomy: Knowledge
86) Molecules that have the same molecular formula but different structural formulas are called
A) isotopes.
B) isomers.
C) isozymes.
D) isotypes.
E) isomoles.
Answer: B
Learning Outcome: 2-9
Bloom's Taxonomy: Knowledge
87) The most important metabolic fuel molecule in the body is
A) sucrose.
B) caffeine.
C) protein.
D) vitamins.
E) glucose.
Answer: E
Learning Outcome: 2-9
Bloom's Taxonomy: Knowledge
88) A polysaccharide that is formed in liver and muscle cells to store glucose is
A) lactose.
B) cellulose.
C) glycogen.
D) sucrose.
E) fructose.
Answer: C
Learning Outcome: 2-9
Bloom's Taxonomy: Knowledge
89) The group of organic compounds containing carbon, hydrogen, and oxygen in a near 1:2:1 ratio is defined as a
A) carbohydrate.
B) lipid.
C) protein.
D) nucleic acid.
E) saturated fat.
Answer: A
Learning Outcome: 2-9
Bloom's Taxonomy: Knowledge
90) An example of an organic substance is:
A) sucrose
B) carbonic acid
C) sodium chloride
D) oxygen
E) nitric oxide
Answer: A
Learning Outcome: 2-9
Bloom's Taxonomy: Knowledge
91) Carbohydrate molecules
A) are the building blocks of cellular membranes.
B) form the regulatory molecules known as enzymes.
C) are the body's most readily available source of energy.
D) are composed of C, H, O, and N atoms.
E) contain the genetic information found in cells.
Answer: C
Learning Outcome: 2-9
Bloom's Taxonomy: Knowledge
92) When two monosaccharides undergo a dehydration synthesis,
A) two new monosaccharides are formed.
B) a disaccharide is formed.
C) a polysaccharide is formed.
D) a starch is formed.
E) hydrolysis occurs.
Answer: B
Learning Outcome: 2-9
Bloom's Taxonomy: Comprehension
93) To bond two monomers together, a molecule of water must be ________ to/from from monomers. This process is called ________.
A) added; hydrolysis
B) removed; dehydration synthesis
C) removed; crenation
D) added; denaturation
E) added; ionization
Answer: B
Learning Outcome: 2-9
Bloom's Taxonomy: Comprehension
94) Lipids
A) form essential structural components of cells.
B) provide a significant energy reserve.
C) help to maintain body temperature.
D) cushion organs against shocks.
E) All of the answers are correct.
Answer: E
Learning Outcome: 2-10
Bloom's Taxonomy: Knowledge
95) A fatty acid that contains two or more double covalent bonds is said to be
A) saturated.
B) monounsaturated.
C) polyunsaturated.
D) hydrogenated.
E) carboxylated.
Answer: C
Learning Outcome: 2-10
Bloom's Taxonomy: Knowledge
96) Alaska Natives have a lower incidence of heart disease even though their diets are high in fat and cholesterol. This may be due to the large amount of ________ in their diets.
A) vitamins
B) triglycerides
C) prostaglandins
D) omega-3 fatty acids
E) oleic acid
Answer: D
Learning Outcome: 2-10
Bloom's Taxonomy: Knowledge
97) Which of the following is/are needed to form a triglyceride molecule?
A) 3 glycerol molecules
B) 1 glycerol molecule
C) 3 fatty acid molecules
D) 3 glycerol molecules and 3 fatty acid molecules
E) 3 fatty acid molecules and 1 glycerol molecule
Answer: E
Learning Outcome: 2-10
Bloom's Taxonomy: Knowledge
98) A shortage of steroids in the body would result in a shortage of
A) sex hormones.
B) proteins.
C) plasma membranes.
D) glycogen.
E) sex hormones and plasma membranes.
Answer: E
Learning Outcome: 2-10
Bloom's Taxonomy: Knowledge
99) Most of the fat found in the human body is in the form of
A) cholesterol.
B) phospholipids.
C) triglycerides.
D) prostaglandins.
E) monoglycerides.
Answer: C
Learning Outcome: 2-10
Bloom's Taxonomy: Knowledge
100) Lipids that are produced by nearly every tissue in the body and act as local regulators are the
A) prostaglandins.
B) steroids.
C) monoglycerides.
D) phospholipids.
E) glycolipids.
Answer: A
Learning Outcome: 2-10
Bloom's Taxonomy: Knowledge
101) Cholesterol, phospholipids, and glycolipids are examples of
A) dietary fats.
B) prostaglandins.
C) structural lipids.
D) lipid drugs.
E) steroids.
Answer: C
Learning Outcome: 2-10
Bloom's Taxonomy: Knowledge
102) A fatty acid with no double bonds between carbon atoms is
A) unsaturated.
B) polyunsaturated.
C) dehydrated.
D) saturated.
E) denatured.
Answer: D
Learning Outcome: 2-10
Bloom's Taxonomy: Knowledge
103) Lipids are composed of fatty acids and
A) glycerol.
B) amino acids.
C) sugars.
D) monosaccharides.
E) polypeptides.
Answer: A
Learning Outcome: 2-10
Bloom's Taxonomy: Knowledge
104) The monomers of protein are
A) glucose.
B) fatty acids.
C) amino acids.
D) nucleotides.
E) nitrogen base.
Answer: C
Learning Outcome: 2-11
Bloom's Taxonomy: Knowledge
105) Substrate molecules bind to enzymes at the ________ sites.
A) amino
B) active
C) carboxyl
D) reactant
E) neutral
Answer: B
Learning Outcome: 2-11
Bloom's Taxonomy: Knowledge
106) You would expect a peptide bond to link
A) two simple sugars.
B) two amino acids.
C) two nucleotides.
D) a sugar and a peptide.
E) a peptide and a fatty acid.
Answer: B
Learning Outcome: 2-11
Bloom's Taxonomy: Knowledge
107) Each amino acid differs from another in the
A) number of central carbon atoms.
B) size of the amino group.
C) number of carboxyl groups.
D) nature of the side chain.
E) number of peptide bonds in the molecule.
Answer: D
Learning Outcome: 2-11
Bloom's Taxonomy: Knowledge
108) The term ________ means each enzyme catalyzes only one type of reaction.
A) saturation
B) specificity
C) inertia
D) activation
E) monoreactive
Answer: B
Learning Outcome: 2-11
Bloom's Taxonomy: Knowledge
109) A side chain on an amino acid is sometimes called ________.
A) fibrous or globular
B) a polypeptide chain
C) an R group
D) an isozyme
E) nucleic acid
Answer: C
Learning Outcome: 2-11
Bloom's Taxonomy: Knowledge
110) The alpha-helix and pleated sheet are examples of ________ protein structure.
A) primary
B) secondary
C) tertiary
D) quaternary
E) pentanary
Answer: B
Learning Outcome: 2-11
Bloom's Taxonomy: Knowledge
111) Interaction between individual polypeptide chains to form a protein complex is ________ structure.
A) primary
B) secondary
C) tertiary
D) quaternary
E) pentagonal
Answer: D
Learning Outcome: 2-11
Bloom's Taxonomy: Knowledge
112) Glycoproteins and proteoglycans are combinations of amino acids and
A) carbohydrates.
B) fatty acids.
C) lipids.
D) nucleic acids.
E) inorganic compounds.
Answer: A
Learning Outcome: 2-11
Bloom's Taxonomy: Knowledge
113) Which of the following is the symbol for an amino group?
A) -COOH
B) -PO3
C) -NH2
D) -AMO
E) -OH
Answer: C
Learning Outcome: 2-11
Bloom's Taxonomy: Knowledge
114) The maximum rate of an enzyme reaction occurs at
A) dehydration.
B) hydrolysis.
C) synthesis.
D) reversible.
E) saturation limit.
Answer: E
Learning Outcome: 2-11
Bloom's Taxonomy: Knowledge
115) How would the lack of a cofactor for an enzyme affect that enzyme's function?
A) The enzyme's function would not be altered.
B) The enzyme would function more slowly.
C) The enzyme would function more quickly.
D) The enzyme would not be able to function.
E) The enzyme would cease to function after reaching a maximum rate.
Answer: D
Learning Outcome: 2-11
Bloom's Taxonomy: Comprehension
116) An example of an organic substance is:
A) lipid
B) nucleic acid
C) protein
D) lipid and protein
E) lipid, nucleic acid, and protein
Answer: E
Learning Outcome: 2-12
Bloom's Taxonomy: Knowledge
117) Molecules that store and process genetic information are the
A) proteins.
B) nucleic acids.
C) carbohydrates.
D) lipids.
E) steroids.
Answer: B
Learning Outcome: 2-12
Bloom's Taxonomy: Knowledge
118) An amino acid is to a protein as ________ is to a nucleic acid.
A) a purine
B) a nucleotide
C) a protein
D) a proton
E) a neutron
Answer: B
Learning Outcome: 2-12
Bloom's Taxonomy: Knowledge
119) A nucleotide consists of
A) a five-carbon sugar and phosphate group.
B) a five-carbon sugar and a nitrogenous base.
C) a phosphate group and a nitrogenous base.
D) a five-carbon sugar, a nitrogenous base, and a phosphate group.
E) a five-carbon sugar and an amino acid.
Answer: D
Learning Outcome: 2-12
Bloom's Taxonomy: Knowledge
120) According to the rules of complementary base pairing in nucleic acids, cytosine would pair with the base
A) thymine.
B) adenine.
C) uracil.
D) cytosine.
E) guanine.
Answer: E
Learning Outcome: 2-12
Bloom's Taxonomy: Knowledge
121) Adenine and guanine are
A) purines represented by T and C.
B) pyrimidines represented by A and G.
C) purines represented by A and G.
D) pyrimidines represented by T and C.
E) nucleotides represented by A and G.
Answer: C
Learning Outcome: 2-12
Bloom's Taxonomy: Knowledge
122) The structure of RNA differs from DNA in that
A) the backbone of RNA contains ribose.
B) RNA contains pyrimidines but not purines.
C) RNA contains purines but not pyrimidines.
D) DNA contains pyrimidines but not purines.
E) DNA contains purines but not pyrimidines.
Answer: A
Learning Outcome: 2-12
Bloom's Taxonomy: Knowledge
123) The most abundant high-energy compound in cells is
A) DNA.
B) adenosine diphosphate.
C) adenosine monophosphate.
D) adenosine triphosphate.
E) RNA.
Answer: D
Learning Outcome: 2-13
Bloom's Taxonomy: Knowledge
124) A high-energy bond in ATP is present
A) between adenine and ribose.
B) between adenine and a phosphate group.
C) between the first and second phosphate group.
D) between the second and third phosphate group.
E) between phosphate groups 1 and 2 and between phosphate groups 2 and 3.
Answer: E
Learning Outcome: 2-13
Bloom's Taxonomy: Knowledge
125) The phosphorylation of adenosine forms
A) ADP.
B) ATP.
C) AMP.
D) 2ATP.
E) ribose.
Answer: C
Learning Outcome: 2-13
Bloom's Taxonomy: Application
126) Identify the product formed from the phosphorylation of ADP.
A) adenosine diphosphate
B) adenine
C) adenosine triphosphate
D) deoxyribonucleic acid
E) ribose
Answer: C
Learning Outcome: 2-13
Bloom's Taxonomy: Knowledge
127) AMP + P →
A) ADP
B) 2ADP
C) DNA
D) ATP
E) adenine
Answer: A
Learning Outcome: 2-13
Bloom's Taxonomy: Knowledge
128) The average time between synthesis and breakdown is known as the ________ time.
A) metabolism
B) anabolism
C) catabolism
D) specificity
E) turnover
Answer: E
Learning Outcome: 2-14
Bloom's Taxonomy: Knowledge
129) Muscle proteins are destroyed after 17 days and then replaced. This is an example of
A) metabolic turnover.
B) surveillance.
C) surface tension.
D) disease.
E) specificity.
Answer: A
Learning Outcome: 2-14
Bloom's Taxonomy: Knowledge
130) Continuous breakdown and replacement of cellular molecules is termed
A) metabolism.
B) metabolic turnover.
C) anabolic turnover.
D) catabolic turnover.
E) organic chemistry
Answer: B
Learning Outcome: 2-14
Bloom's Taxonomy: Knowledge
Short Answer Questions
131) A(n) ________ is a pure substance composed of atoms of only one kind.
Answer: element
Learning Outcome: 2-1
Bloom's Taxonomy: Knowledge
132) The center of an atom is called the ________.
Answer: nucleus
Learning Outcome: 2-1
Bloom's Taxonomy: Knowledge
133) Electrons whirl around the center of the atom at high speed, forming a(n) ________.
Answer: electron cloud
Learning Outcome: 2-1
Bloom's Taxonomy: Knowledge
134) Electrons in an atom occupy an orderly series of electron shells or ________.
Answer: energy levels
Learning Outcome: 2-1
Bloom's Taxonomy: Knowledge
135) The actual mass of an atom is known as its ________ ________.
Answer: atomic weight
Learning Outcome: 2-1
Bloom's Taxonomy: Knowledge
136) Atoms of the same element whose nuclei contain the same number of protons, but different numbers of neutrons, are called ________.
Answer: isotopes
Learning Outcome: 2-1
Bloom's Taxonomy: Knowledge
137) The ________ of a radioactive substance is the time required for 50 percent of a given amount of radioisotope to decay.
Answer: half-life
Learning Outcome: 2-1
Bloom's Taxonomy: Knowledge
138) Ions with a positive charge are called ________.
Answer: cations
Learning Outcome: 2-2
Bloom's Taxonomy: Knowledge
139) Ions with a negative charge are called ________.
Answer: anions
Learning Outcome: 2-2
Bloom's Taxonomy: Knowledge
140) Kinetic energy is stored as ________ energy when a spring is stretched.
Answer: potential
Learning Outcome: 2-3
Bloom's Taxonomy: Knowledge
141) Chemical reactions that release energy are called ________.
Answer: exergonic
Learning Outcome: 2-3
Bloom's Taxonomy: Knowledge
142) Chemical reactions that absorb energy are called ________.
Answer: endergonic
Learning Outcome: 2-3
Bloom's Taxonomy: Knowledge
143) The three familiar states of matter are solids, liquids, and ________.
Answer: gases
Learning Outcome: 2-3
Bloom's Taxonomy: Knowledge
144) Chemical reactions that occur in the body are accelerated by ________.
Answer: enzymes
Learning Outcome: 2-4
Bloom's Taxonomy: Knowledge
145) In living cells, complex metabolic reactions proceed in a series of steps called a(n) ________.
Answer: pathway
Learning Outcome: 2-4
Bloom's Taxonomy: Knowledge
146) Compounds that contain carbon as the primary structural atom are called ________ molecules.
Answer: organic
Learning Outcome: 2-5
Bloom's Taxonomy: Knowledge
147) Compounds that do not usually contain carbon as the primary structural atom are called ________ molecules.
Answer: inorganic
Learning Outcome: 2-5
Bloom's Taxonomy: Knowledge
148) A(n) ________ is a homogeneous mixture containing a solvent and a solute.
Answer: solution
Learning Outcome: 2-6
Bloom's Taxonomy: Knowledge
149) Soluble inorganic compounds whose solutions will conduct an electric current are called ________.
Answer: electrolytes
Learning Outcome: 2-6
Bloom's Taxonomy: Knowledge
150) Molecules that do not readily interact with water are called ________.
Answer: hydrophobic
Learning Outcome: 2-6
Bloom's Taxonomy: Knowledge
151) The ________ of a solution is the negative logarithm of the hydrogen ion concentration expressed in moles per liter.
Answer: pH
Learning Outcome: 2-7
Bloom's Taxonomy: Knowledge
152) All fatty acids contain a functional group at one end called the ________.
Answer: carboxylic acid group
Learning Outcome: 2-10
Bloom's Taxonomy: Knowledge
153) In water, phospholipids tend to form tiny droplets with hydrophobic tails buried inside called ________.
Answer: micelles
Learning Outcome: 2-10
Bloom's Taxonomy: Knowledge
154) Molecules with two fatty acid chains and a phosphate group that form biological membranes are called ________.
Answer: phospholipids
Learning Outcome: 2-10
Bloom's Taxonomy: Knowledge
155) Individual steroids differ in the ________ attached to the carbon rings.
Answer: side chains
Learning Outcome: 2-10
Bloom's Taxonomy: Knowledge
156) The molecule DNA contains a five-carbon sugar called ________.
Answer: deoxyribose
Learning Outcome: 2-12
Bloom's Taxonomy: Knowledge
157) The purines found in DNA are ________ and guanine.
Answer: adenine
Learning Outcome: 2-12
Bloom's Taxonomy: Knowledge
158) The pyrimidine bases found in DNA are ________ and cytosine.
Answer: thymine
Learning Outcome: 2-12
Bloom's Taxonomy: Knowledge
159) The three structural components of a nucleotide are a pentose, a phosphate group, and a _______ base.
Answer: nitrogenous
Learning Outcome: 2-12
Bloom's Taxonomy: Knowledge
160) A(n) ________ is a covalent bond that stores an unusually large amount of energy.
Answer: high-energy bond
Learning Outcome: 2-13
Bloom's Taxonomy: Knowledge
161) In the process of ________ a phosphate group is transferred to a molecule.
Answer: phosphorylation
Learning Outcome: 2-13
Bloom's Taxonomy: Knowledge
162) The hydrolysis of ATP yields ADP, phosphate ion, and ________.
Answer: energy
Learning Outcome: 2-13
Bloom's Taxonomy: Knowledge
Essay Questions
163) The element sulfur has an atomic number of 16 and mass number of 32. How many neutrons are in the nucleus of a sulfur atom? If sulfur forms covalent bonds with hydrogen, how many hydrogen atoms can bond to one sulfur atom?
Answer: The number of neutrons in an atom is equal to the mass number minus the atomic number. Thus, sulfur has 32 - 16 = 16 neutrons. The atomic number indicates the number of protons, so a neutral sulfur atom contains 16 protons plus 16 electrons to balance the protons electrically. The electrons would be distributed as follows: 2 in the first electron shell, 8 in the second, and the remaining 6 in the third. To achieve a full 8 electrons in the third (outermost) electron shell, the sulfur atom can accept 2 electrons in an ionic bond or can share 2 electrons in a covalent bond. Because hydrogen atoms can share one electron in a covalent bond, the sulfur atom can form two covalent bonds with hydrogen, one with each of two hydrogen atoms. In chemical notation, this is H2S.
Learning Outcome: 2-2
Bloom's Taxonomy: Application
164) What role do buffer systems play in the human body?
Answer: Buffer systems help maintain pH within normal limits by removing or replacing hydrogen ions as needed.
Learning Outcome: 2-7
Bloom's Taxonomy: Comprehension
165) Blood has a very narrow normal pH range but urine has a very broad normal pH range. What does that indicate about the physiology of pH?
Answer: Homeostasis requires that the pH of body fluids be maintained almost constant to avoid disruptions of healthy function. To accomplish this, the urinary system eliminates or retains hydrogen ion as needed. These actions cause the pH of urine to vary widely, depending on whether there is too much or not enough hydrogen ion in the body.
Learning Outcome: 2-7
Bloom's Taxonomy: Application
166) Explain the role of water molecules in polysaccharide formation.
Answer: Water molecules are removed in the dehydration synthesis of polysaccharides.
Learning Outcome: 2-9
Bloom's Taxonomy: Comprehension
167) How does the DNA molecule control the appearance and function of a cell?
Answer: The DNA molecule controls the synthesis of enzymes and structural proteins. By controlling the synthesis of structural proteins, the DNA is able to influence the physical appearance of a cell. By controlling the production of enzymes, the DNA is able to control all aspects of cellular metabolism and thus control the activity and biological functions of the cell.
Learning Outcome: 2-12
Bloom's Taxonomy: Application
of Organization
Introduction to the Chapter
The molecular level of organization is the smallest that we study in anatomy and physiology. Occurring all around us and inside our cells are atomic and molecular reactions that we are unable to see in daily life, and yet you need to make it clear to your students that these reactions are profoundly important. They need to understand that all thought, movement, and memory rest upon ions interacting with protein molecules suspended in a boundless sea of fluid phospholipids, the plasma membrane. The enzymatic breakdown of sugars and fats yields the energy that powers our bodies and enables adding new molecules to the body during growth, development, and repair. The endocrine system is built around chemical signals.
Biotechnology has enabled us to sequence the human genome to discover our relatedness to the rest of life on Earth. With the information from the genome, we are now working to determine which gene produces which protein so we may begin to track the development of disease and other disorders to which humans are susceptible. We know the nucleotide sequence of our chromosomes and we can see the genetic information that makes us human. With this information, it will be possible to further “type” humans into subgroups that are susceptible to specific diseases and disorders. This will allow doctors to prescribe medication that is more specific and works faster than the medications we use today. Hopefully, this will alleviate the number of side effects that can occur with various medications. Progress has been made in diseases such as breast cancer, diabetes, certain heart conditions, blood pressure regulation, and prostate cancer. It will take time and money, but the eventual goal is to be able to
“personalize” treatment and medication based on each individual’s genetic makeup.
Chapter Learning Outcomes
2-1 Describe an atom and how atomic structure affects interactions between atoms.
2-2 Compare the ways in which atoms combine to form molecules and compounds.
2-3 Distinguish among the major types of chemical reactions that are important for
studying physiology.
2-4 Describe the crucial role of enzymes in metabolism.
2-5 Distinguish between organic and inorganic compounds.
2-6 Explain how the chemical properties of water make life possible.
2-7 Discuss the importance of pH and the role of buffers in body fluids.
2-8 Describe the physiological roles of inorganic compounds.
2-9 Discuss the structures and functions of carbohydrates.
2-10 Discuss the structures and functions of lipids.
2-11 Discuss the structures and functions of proteins.
2-12 Discuss the structures and functions of nucleic acids.
2-13 Discuss the structures and functions of high-energy compounds.
2-14 Explain the relationship between chemicals and cells.
Teaching Strategies
1. Lecture Ideas and Key Points to Emphasize
a. Chemistry is often a difficult subject for students. It involves quite a bit of math;
therefore, many students avoid it. But if they are planning on a career in the health field, they have to understand certain chemical concepts. It is a challenge to get
students to understand the importance of what you are teaching them. It’s a good idea to start with the smaller, easier to comprehend topics before moving on to reactions and equations. Start with atomic number, chemical symbol, element, and atomic weight, and slowly work up to the periodic table. In terms of electron orbitals, explain the horizontal and vertical arrangement of the elements, and point out the periodicity. In support of the crucial role that careful observation plays, you can point out that Mendeleev, the author of the best-accepted periodic table in the 1860s, lacked a
comprehensive structural model of the atom, commonplace today, but still saw and
ordered the periodicities.
b. Present chemical bonds on a need-to-know basis. The most important in physiology are ionic bonds, covalent bonds, and hydrogen bonds. Even though a single hydrogen bond possesses only about 1/100 of the bonding energy of a covalent bond, the total energy of all the hydrogen bonds within a single molecule or between molecules
can be quite significant. H bonds maintain the 3-D shape of large molecules and
supramolecular ensembles such as proteins and nucleic acids. It is the H bonds that are disrupted when pH drops or temperature rises during denaturation reactions.
c. It is important to illustrate that H bonds occur between separate molecules (or distant regions of a large molecule) whose atoms are joined by covalent bonds. A board
drawing of several water molecules, with both the polar covalent bonds and the
H bonds clearly labeled, will emphasize this point.
d. Figure 2–7 on chemical notation is a lot of information for beginning A&P students. However, knowledge of chemical notation will become an essential tool in their professional “toolkit,” needed now and down the road in their future training and practice. Dosage and calculations, pharmacology, and many other advanced classes require a good knowledge of chemistry. The health care fields require more than just a passing knowledge of chemistry and chemical notation. Getting the dosage wrong can result in many problems. Even something as simple as an injection for allergies can be measured wrong and too much can send a patient into anaphylactic shock. It is important to teach this material slowly and thoroughly, making sure all students are involved in what you are saying. Clicker cases may help, but don’t overwhelm them. You may find that when you teach chemistry a little slower with an application emphasis, your students will pick it up better.
e. It is hard to overemphasize the significance of enzymes. In the first case, it is the first form of molecular recognition students will encounter in the course. The lock-and-key fit between enzyme and substrate molecule is what confers specificity on the catalyzed reaction. Later examples include hormone receptors, channels, carriers, pumps, second messengers, cell adhesion molecules, and neurotransmission. Enzymes are what make life possible. Living organisms cannot survive at temperatures much higher than 120°C. Point out that most reactions require a lot of heat to go forward. Enzymes
function by lowering the amount of energy a reaction needs in order to take place. The chemical reactions in our bodies can occur at 37ºC due to the presence of enzymes. Chemical reactions start with reactants that are rearranged to form different end products. For a reaction to go forward, energy is required and enzymes lower the amount of energy required. While a reaction results in chemically rearranged end products, the enzyme itself still retains its original shape and can carry out the same reaction over and over.
f. When presenting the different classes of reactions, anticipate their roles in metabolism (catabolic vs. anabolic). Also, link each with an important physiological example, such as dissociation/association to the chemistry of carbonic acid dissociation/association. This connects to buffering reactions as well.
2. Analogies
a. Anthropomorphize molecules by describing them as both “greedy” and “lazy.” They want their outer energy level complete, and will look around for someone else’s excess electrons. However, they are lazy; they won’t take on more than half the number of electrons required to fill the level. In those cases, they would just as soon give up the electrons in the outer energy level but will be left with one less energy level. A few molecules are lucky enough to come equipped with completed outer energy levels. The noble gases do not interact with anyone! Likewise, if atoms can’t agree on who is
going to give up an electron to make an ionic bond, they may form even stronger covalent bonds by simply sharing the electron in their outer shells. Some atoms express electronegativity when in a compound. This means that bonding electrons spend more time in their neighborhood, conferring a partial negative on them. This induces a corresponding electropositivity on other atoms within a compound. “Hydrogen bonds” form between the partly-charged oxygen atom and a hydrogen atom of two neighboring water molecules and confer many of water’s unusual properties.
b. Compare the primary structure of a protein to a toy train made up of many types of cars (amino acids). When hooking the cars together, there is a definite front and back, just like the C- and N-terminus of a polypeptide chain. The chain of cars may be made as long as you wish and of very different form and function by assembling boxcars, passenger cars, club cars, baggage cars, tank cars, and so on. The hydrolytic digestive enzymes can be analogized to railroad workers that separate the cars at their couplings, thus making the cars available to form new trains.
c. Enzymes will work at their optimum rate as long as there is plenty of substrate, and other conditions are favorable. Think of a roofer fixing a roof. He pounds in nails to hold down shingles (combining two substrates to produce a product), and can use the same hammer again and again (enzymes are catalysts not consumed in the reaction). This process can continue as long as there are nails and shingles.
d. Compare one strand of DNA to a spiral staircase: The alternating sugar and phosphate groups make up the helical supports, while the bases are analogous to the steps. Of course, DNA is made of two antiparallel helices, which would be a very confusing stairway!
e. Enzymes can be thought to work like helpers getting a car from down in one valley, over the hill, and down into a lower valley. The enzyme “lowers the hill,” making it easier to get from one side to the other with much less kinetic (heat) energy. Enzymes don’t change where you start or where you finish but just make it easier (and thus faster) to get over the hill. Refer to Figure 2–8 during this analogy.
3. Demonstrations
a. Compare the different levels of protein structure with ribbon used to wrap a package. A ribbon can be stretched out straight (primary), coiled in a spiral (secondary), or stripped with scissors so that it develops many overlapping curls (tertiary). You can even bunch several of the curly ribbons together to make a wreath (quaternary). You can also use an old-fashioned phone cord to represent the coiling of the protein molecule (secondary, tertiary, and quaternary structures).
b. To make dramatically clear and concrete the difficult concept of the mole as an Avogadro’s number of particles (and to introduce the value of the “gedanken
experiment” [thought experiment] in scientific reasoning), try this simple but interesting lecture or lab exercise. Ask the students how they could count out 6.023 ´ 1023
water molecules. Answer: by weighing exactly 18 grams of water! Spell it out:
1 mole of oxygen (16 grams) + 2 moles of hydrogen (2 grams) = 18 grams
Ask them to visualize how much water this is (a bit over ½ ounce). Repeat for other molecules, such as the monosaccharide fructose or glucose (180 grams). How big a pile would this make? (about 120 mL) How much for the disaccharide sucrose? (342 grams, about 207 mL) Why not 360 (180 ´ 2)? Because sucrose is formed in a condensation reaction (a loss of one water molecule, 18 grams). How much would a mole of hemoglobin weigh? Answer: 64 kg (141 lb)! Ask them to imagine that. Very
different-sized piles of molecules, but yet all have the same number of particles, an Avogadro’s number of them, 6.023 ´ 1023. This thought exercise should impress on them the physical meaning of “mole” (and the power and importance of imagination in scientific thinking).
4. Applications
a. During the discussion of free radicals, mention the strong evidence that eating plentiful amounts of fruits and vegetables high in antioxidants (and thus, presumably better able to quench free radicals) protect against cancer, heart disease, and possibly other grave illnesses. Oddly, little benefit, and sometimes harm, results when the antioxidant nutrients are consumed in pure form, away from the foods in which they naturally occur in goodly amount.
b. Indicate that prostaglandins are found in most cells. Stress that their importance as chemical signals will become clear later in the text. They are also considered tissue hormones. They help with inflammation and pain but do not get into the blood supply.
c. Explain the role of cholesterol, both as a membrane component and as starting material for steroid hormones. Also mention that there are two sources for cholesterol. One is diet, and the other is genetic. If someone has high cholesterol, diet and exercise may work to reduce it. But for some unlucky few, they can exercise and diet and there will be no reduction in their cholesterol level. There is a genetic factor that causes the liver
to produce more cholesterol than normal. This affects mostly people from the area of the Mediterranean Sea.
d. Explain the structural and functional roles of phospholipids and glycolipids. You can use Figure 2–18c to anticipate the phospholipid bilayer by asking the students to imagine what would result if a spherical micelle were flattened.
e. Solutions are very important in biology and medicine. Be sure they are clear about how a solution forms, which is the solute, and which the solvent. The cell cytoplasm and the blood plasma are good examples of complex biological solutions.
5. Common Student Misconceptions and Problems
a. Each integer change in pH value represents a tenfold change in the concentration of hydrogen ions. The lower the pH value, the higher the concentration of hydrogen ions. If the blood pH is 7.3, although an alkaline pH, it is slightly more acidic than the
normal pH of blood (7.35–7.45). Hydrogen ions affect the pH only if they are in
solution. A buffer acts like an ion sponge, binding or releasing hydrogen ions and so limits changes in pH if hydrogen ions are added or removed from solution.
b. Anticipate the possible confusion between the alpha helix in the secondary structure of proteins and the double helix of the two complementary antiparallel strands in DNA.
c. Clarify that “cholesterol” is not merely a “bad” thing but an important body chemical. It is a component of many cell membranes, plasma lipoproteins, and the source of
steroid hormones. However, it is particular cholesterol compounds that promote cardiovascular disease.
6. Terminology Aids
a. For mnemonics for cation vs. anion (that is, positive ion vs. negative ion), let the “t” in cation remind you of a “1”: ca1ion. Also, let ANion remind you of A Negative ion.
b. To distinguish hydrophilic from hydrophobic, remember that “phobia” is a fear, in this case, molecules that fear (or hate) water. Also, hydrophilic ends with “lic,” which
resembles “like,” that is, water-liking molecules.
c. Let them see that carbohydrates are literally “hydrated water” or “carbo-” +
“-hydrate”; that is, their chemical formula is an integral number of “C–H2O”. Thus
glucose, galactose, and fructose are all C6H12O6, that is, 6 × C•H2O. Disaccharides, of any class, are all C12H22O11. A molecule of water is lost when the chemical bond is created. Here is a way to challenge your students: put the formula C12H22O11 on the board and ask them to apply their knowledge of the chemical formula for a disaccharide to this formula. Ask them to point out what is missing. If they correctly understand the chemical notation, they will see that there are 2 hydrogens and one oxygen missing from the formula on the board. This is the molecule of water that is lost when a disaccharide bonds with another sugar molecule. It would be a challenge for students to see the missing water molecule. C12H24O12 minus a molecule of water is H2O = C12H22O11.
No comments:
Post a Comment