Biochemistry 4th Edition by Donald Voet Test Bank

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Biochemistry 4th Edition by Donald Voet Test Bank

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WITH ANSWERS

Biochemistry 4th Edition by Donald Voet Test Bank

Chapter 2: Water

 

 

Matching

 

A) hydrogen bond
B) rotational
C) H3PO4
D) H2PO4
E) HPO4 2
F) disordered
G) positive entropy
H) negative entropy
I) higher electronegativity
J) insoluble
K) tetrahedral arrangement
L) acid
M) base
N) only partially ionized

 

 

  1. Translational and ______ thermal motion causes liquid water molecules to reorient approximately every 1012 seconds.

 

Ans:  B

Level of Difficulty:  Easy

Section:  2.1.A

Learning objective: Physical Properties of Water

 

 

  1. The 104.5 bond angle in the water molecule is the result of the ______ of electron orbitals around oxygen.

 

Ans:  K

Level of Difficulty:  Easy

Section:  2.1.A

Learning objective: Physical Properties of Water

 

 

  1. The polarity of the OH bond is caused by the ______ of oxygen relative to that of hydrogen.

 

Ans:  I

Level of Difficulty:  Easy

Section:  2.1.A

Learning objective: Physical Properties of Water

 

  1. For the ______ represented by DHA, the donor D is weakly acidic and the acceptor A is weakly basic.

 

Ans:  A

Level of Difficulty:  Easy

Section:  2.1.A

Learning objective: Physical Properties of Water

 

 

  1. Octane molecules dispersed in water tend to aggregate because that allows water molecules to be more ______.

 

Ans:  F

Level of Difficulty:  Easy

Section:  2.1.C

Learning objective: Physical Properties of Water

 

 

  1. The insolubility of nonpolar molecules in water is due to the large ______, which is the result of water molecules forming an ordered network surrounding nonpolar molecules.

 

Ans:  H

Level of Difficulty:  Moderate

Section:  2.1.C

Learning objective: Physical Properties of Water

 

 

  1. A strong acid is completely ionized in water, whereas a weak acid is ______.

 

Ans:  N

Level of Difficulty:  Easy

Section:  2.2.B

Learning objective: Chemical Properties of Water

 

 

  1. Phosphate (pK1 = 2.15, pK2 = 6.82, and pK3 = 12.38) will be mostly in the HPO42 form at pH 7.2. At pH 5.82 it is mostly in the ______ form.

 

Ans:  D

Level of Difficulty:  Moderate

Section:  2.2.C

Learning objective: Chemical Properties of Water

 

  1. A solution containing a weak acid (pK = 7.5) and its conjugate base at pH of 8.5 has a good capacity to buffer the addition of ______.

 

Ans:  L

Level of Difficulty:  Moderate

Section:  2.2.C

Learning objective: Chemical Properties of Water

 

 

  1. A phosphate buffer solution at pH = pK1 = 2.15 would have equal amounts of phosphate in the ______ form and the H2PO4 form.

 

Ans:  C

Level of Difficulty:  Easy

Section:  2.2.C

Learning objective: Chemical Properties of Water

 

 

Multiple Choice

 

  1. Rank the following interactions in order of increasing strength (start with the weakest interaction).
  2. A) ionic interactions, hydrogen bonds, London dispersion forces, covalent bonds
  3. B) London dispersion forces, hydrogen bonds, ionic interactions, covalent bonds
  4. C) London dispersion forces, ionic interactions, hydrogen bonds, covalent bonds
  5. D) covalent bonds, London dispersion forces, ionic interactions, hydrogen bonds
  6. E) hydrogen bonds, London dispersion forces, ionic interactions, covalent bonds

 

Ans:  B

Level of Difficulty:  Easy

Section:  2.1.A

Learning objective: Physical Properties of Water

 

 

  1. The strongest noncovalent interactions are
  2. A) ionic interactions.
  3. B) hydrogen bonds.
  4. C) dipole-dipole interactions.
  5. D) London dispersion forces.
  6. E) van der Waals forces.

 

Ans:  A

Level of Difficulty:  Easy

Section:  2.1.A

Learning objective: Physical Properties of Water

 

  1. Hydrogen bonds within liquid water
  2. A) are attractions between protons and oxygen nuclei.
  3. B) are attractions between two hydrogen atoms.
  4. C) are attractions between protons and hydroxide ions.
  5. D) are ion-induced dipole attractions.
  6. E) are dipole-dipole attractions.

 

Ans:  E

Level of Difficulty:  Easy

Section:  2.1.A

Learning objective: Physical Properties of Water

 

 

  1. Urea is a water-soluble product of nitrogen metabolism. How many hydrogen bonds can one urea molecule donate to surrounding water molecules?

 

 

  1. A) 2
  2. B) 3
  3. C) 4
  4. D) 5
  5. E) 6

 

Ans:  C

Level of Difficulty:  Moderate

Section:  2.1.A

Learning objective: Physical Properties of Water

 

  1. Methanol can act both as a H-bond donor and as a H-bond acceptor. What is the maximal number of H-bonds a single molecule of methanol can form with surrounding water molecules.

 

  1. A) 1
  2. B) 2
  3. C) 3
  4. D) 4
  5. E) 5

 

Ans:  C

Level of Difficulty:  Moderate

Section:  2.1.A

Learning objective: Physical Properties of Water

 

 

  1. In a hydrogen bond between a water molecule and another biomolecule
  2. A) a hydrogen ion on the water molecule forms an ionic bond with a hydride ion on the other molecule.
  3. B) the partial charge on a hydrogen of the water molecule interacts with the partial charge on a hydrogen of the other molecule.
  4. C) the hydrogen bond will typically form between a hydrogen atom of the water molecule and either a nitrogen, sulfur, or oxygen atom of the other molecule.
  5. D) a hydrogen on the water molecule forms a covalent bond with a hydrogen atom on the other molecule.
  6. E) the hydrogen atom is located between an oxygen atom of the water and a carbon atom of the other molecule.

 

Ans:  C

Level of Difficulty:  Easy

Section:  2.1.A

Learning objective: Physical Properties of Water

 

 

  1. Which of the following statements about water is not true?
  2. A) It has a high dielectric constant.
  3. B) It dissolves salts and polar substances.
  4. C) It can form two hydrogen bonds per water molecule.
  5. D) It packs in a hexagonal (honeycomb) shaped lattice when the temperature falls below 0C.
  6. E) In the liquid state it is only 15% less hydrogen bonded than in the solid state at 0

 

Ans:  C

Level of Difficulty:  Easy

Section:  2.1.A

Learning objective: Physical Properties of Water

 

  1. Which of the following statements about water is not true?
  2. A) The electron-rich oxygen atom of one water molecule can interact with the electron-poor proton on another water molecule to form a hydrogen bond.
  3. B) Liquid water is only 15% less hydrogen bonded than ice.
  4. C) Water is a nonpolar molecule that with a bent molecular geometry.
  5. D) Water can form highly ordered, cage-like, structures around nonpolar molecules.
  6. E) Water is a key player in the energetics of hydrophobic interactions.

 

Ans:  C

Level of Difficulty:  Easy

Section:  2.1.A

Learning objective: Physical Properties of Water

 

 

11.
  1. Which of the following statements about water is incorrect?
  2. A) Water is an excellent solvent for polar molecules.
  3. B) Pure water has a concentration of approximately 55.5 M.
  4. C) Cations are solvated by shells of water molecules oriented with their hydrogen atoms pointed toward the ions.
  5. D) Nonpolar molecules do not dissolve in water, but form a separate phase.
  6. E) Amphiphilic detergents often form micelles with the polar groups on the outside exposed to water (solvent) and the nonpolar groups sequestered in the interior.

 

Ans:  C

Level of Difficulty:  Easy

Section:  2.1.A

Learning objective: Physical Properties of Water

 

 

  1. Which of the following statements about water is incorrect?
  2. A) It is a small, polar molecule with a low dielectric constant.
  3. B) It has a marked dipole moment.
  4. C) It is largely hydrogen bonded, although any single H-bond exists only for a very short period of time (~10-12 s ).
  5. D) Acid-base reactions are very fast due to the mobility of hydronium ions in water which is a consequence of the ability of individual protons to jump from one water molecule to another.
  6. E) It has a bent geometry with each OH bond approximately 0.958 long and with an OH bond energy of approximately 460 kJ/mol.

 

Ans:  A

Level of Difficulty:  Easy

Section:  2.1.A

Learning objective: Physical Properties of Water

 

  1. Ice
  2. A) is a crystal of water molecules packed in an open structure stabilized by hydrogen bonds.
  3. B) is less dense than liquid water.
  4. C) contains 17% more hydrogen bonds then water.
  5. D) All of the statements above are true.
  6. E) None of the statements above are true.

 

Ans:  D

Level of Difficulty:  Easy

Section:  2.1.A

Learning objective: Physical Properties of Water

 

 

  1. Covalent CC and CH bonds have bond strengths that are approximately ____ times higher than those of H-bonds.
  2. A) 2
  3. B) 5
  4. C) 10
  5. D) 20
  6. E) 100

 

Ans:  D

Level of Difficulty:  Easy

Section:  2.1.A

Learning objective: Physical Properties of Water

 

 

  1. The boiling point of water is 264C higher than the boiling point of methane because
  2. A) the molecular mass of methane is much lower than that of water.
  3. B) methane molecules tend to avoid contact with each other.
  4. C) water molecules are connected to each other by H-bonds.
  5. D) methane molecules do not undergo London dispersion forces.
  6. E) all of the above

 

Ans:  C

Level of Difficulty:  Easy

Section:  2.1.A

Learning objective: Physical Properties of Water

 

  1. _____ is exceptionally soluble in water due to the formation of hydrogen bonds.
  2. A) NaCl
  3. B) Benzene
  4. C) Sodium palmitate
  5. D) Ethanol
  6. E) Oxygen

 

Ans:  D

Level of Difficulty:  Easy

Section:  2.1.B

Learning objective: Physical Properties of Water

 

 

  1. Molecules such as methanol and ethanol are very soluble in water because
  2. A) they tend to avoid contact with each other.
  3. B) they contain CH groups that donate H-bonds to water.
  4. C) they contain CH groups that accept H-bonds from water
  5. D) they contain OH groups that can form multiple H-bonds with water.
  6. E) they do not form intermolecular H-bonds

 

Ans:  D

Level of Difficulty:  Easy

Section:  2.1.B

Learning objective: Physical Properties of Water

 

 

  1. Hydrophobic interactions between nonpolar molecules
  2. A) result from the tendency of water to maximize contact with nonpolar molecules.
  3. B) are the result of strong attractions between nonpolar molecules.
  4. C) are the result of strong repulsion between water and nonpolar molecules.
  5. D) depend on strong permanent dipoles in the nonpolar molecules.
  6. E) require the presence of surrounding water molecules.

 

Ans:  E

Level of Difficulty:  Easy

Section:  2.1.C

Learning objective: Physical Properties of Water

 

  1. Fatty acids such as palmitate and oleate are usually characterized as
  2. A)
  3. B)
  4. C)
  5. D) water soluble.
  6. E)

 

Ans:  E

Level of Difficulty:  Easy

Section:  2.1.C

Learning objective: Physical Properties of Water

 

 

  1. Amphiphilic molecules
  2. A) have both oxidizing and reducing groups.
  3. B) are micelles.
  4. C) have chromophores in two different wavelength regions.
  5. D) have both acidic and basic groups.
  6. E) have both hydrophilic and hydrophobic groups.

 

Ans:  E

Level of Difficulty:  Easy

Section:  2.1.C

Learning objective: Physical Properties of Water

 

 

  1. Which of the following statements about hydrophobic interactions is not true?
  2. A) They are caused by hydrophobic molecules interacting strongly with each other.
  3. B) They are the driving force for micelle formation.
  4. C) When nonpolar molecules come in contact with water, a highly-ordered shell of water molecules forms at the interface between the nonpolar molecules and water. A hydrophobic interaction is caused by the desire of water molecules to regain the entropy lost during this organization around the nonpolar substance by excluding the substance from interaction with water molecules.
  5. D) They are entropy driven.
  6. E) They are the main driving force for protein folding into three dimensional structures.

 

Ans:  A

Level of Difficulty:  Easy

Section:  2.1.C

Learning objective: Physical Properties of Water

 

  1. Which of the following is the best explanation for the hydrophobic effect?
  2. A) It is caused by an affinity of hydrophobic groups for each other.
  3. B) It is caused by the affinity of water for hydrophobic groups.
  4. C) It is an entropic effect, caused by the desire of water molecules to increase their entropy by forming highly ordered structures around the hydrophobic groups.
  5. D) It is an entropic effect, caused by the desire of water molecules to increase their entropy by excluding hydrophobic groups, which they must otherwise surround with highly ordered structures.
  6. E) It is an entropic effect caused by the desire of hydrophobic groups to increase their entropy by associating with other hydrophobic groups.

 

Ans:  D

Level of Difficulty:  Difficult

Section:  2.1.C

Learning objective: Physical Properties of Water

 

 

  1. In the energetics of transferring hydrocarbons from water to nonpolar solvents, the factor TDS is commonly
  2. A)
  3. B)
  4. C)
  5. D)
  6. E) assumed to be zero.

 

Ans:  B

Level of Difficulty:  Easy

Section:  2.1.C

Learning objective: Physical Properties of Water

 

 

  1. Globules of up to several thousand amphiphilic molecules arranged with the hydrophilic groups on the surface and the hydrophobic groups buried in the center that form in water are called
  2. A)
  3. B)
  4. C)
  5. D) bilayer membranes.
  6. E) none of the above

 

Ans:  A

Level of Difficulty:  Easy

Section:  2.1.C

Learning objective: Physical Properties of Water

 

  1. Sheets composed of two layers of amphipathic molecules arranged with the hydrophilic groups on the surface and the hydrophobic groups buried in the center that form in water are called
  2. A)
  3. B)
  4. C)
  5. D) bilayer membranes.
  6. E) none of the above

 

Ans:  D

Level of Difficulty:  Easy

Section:  2.1.C

Learning objective: Physical Properties of Water

 

 

  1. Physical properties that depend on the amounts of various species, rather than the identities of those species, are called
  2. A) osmotic properties.
  3. B) hydrophobic properties.
  4. C) London dispersion forces.
  5. D) aggregate properties.
  6. E) colligative properties.

 

Ans:  E

Level of Difficulty:  Easy

Section:  2.1.B

Learning objective: Physical Properties of Water

 

 

  1. Osmotic pressure is a function of
  2. A)
  3. B) solute size.
  4. C) solute concentration.
  5. D) van der Waals forces.
  6. E) solute vapor pressure.

 

Ans:  C

Level of Difficulty:  Easy

Section:  2.1.A

Learning objective: Physical Properties of Water

 

  1. Kw, the ionization constant of water, is _____ at _____.
  2. A) 10-7; 25C
  3. B) 107; 25K
  4. C) 1014; 25C
  5. D) 1014; 25C
  6. E) 1014; 0C

 

Ans:  D

Level of Difficulty:  Easy

Section:  2.1.A

Learning objective: Physical Properties of Water

 

 

  1. Weak acids
  2. A) are only partially ionized in an aqueous solution.
  3. B) give solutions with a high pH.
  4. C) do not provide hydronium ions.
  5. D) are almost insoluble in water.
  6. E) are of no value in a buffering system.

 

Ans:  A

Level of Difficulty:  Easy

Section:  2.2.B

Learning objective: Chemical Properties of Water

 

 

  1. A solution is made by mixing 0.05 mL of 1.0 M HCl with 999.95 mL of pure water. Calculate the pH of the resulting solution (assume the total volume is 1.0 L).
  2. A) 7
  3. B) 3
  4. C) 7
  5. D) 7.0
  6. E) 0

 

Ans:  B

Level of Difficulty:  Easy

Section:  2.2.B

Learning objective: Chemical Properties of Water

 

  1. The pH of coffee is 5.6. The pH of grapefruit juice is 2.6.  This means that the proton concentration in coffee is
  2. A) a thousand times higher than in grapefruit juice.
  3. B) a thousand times lower than in grapefruit juice.
  4. C) 3000 times lower than in grapefruit juice.
  5. D) 3 times the proton concentration of grapefruit juice.
  6. E) 3000 times higher than in grapefruit juice.

 

Ans:  B

Level of Difficulty:  Easy

Section:  2.2.B

Learning objective: Chemical Properties of Water

 

  1. A solution is made by mixing 1.0 mL of 1.0 M acetic acid (pK = 4.76, Ka = 1.74 x 105 ) with one 999 mL of pure water. Calculate the pH of the resulting solution (assume the total volume is 1.0 L).
  2. A) 1
  3. B) 0
  4. C) 0
  5. D) 9
  6. E) 32

 

Ans:  D

Level of Difficulty:  Easy

Section:  2.2.B

Learning objective: Chemical Properties of Water

 

 

  1. You mix 999 mL pure water and 1 mL of 2.0 M NaOH. Calculate the pH of the resulting solution. (assume the total volume is 1.0 L).
  2. A) 3
  3. B) 7
  4. C) 7
  5. D) 3
  6. E) 7

 

Ans:  D

Level of Difficulty:  Easy

Section:  2.2.B

Learning objective: Chemical Properties of Water

 

  1. The pH of a 0.1 M solution of sodium acetate would be
  2. A) basic, because of the acetate ion reacts with water to form acetic acid and OH.
  3. B) acidic, because the acetate ion is acidic.
  4. C) acidic, because the acetate ion forms acetic acid.
  5. D) neutral, because salts are neither acidic nor basic.
  6. E) basic, because the Na+ ionizes and combines with OH.

 

Ans:  A

Level of Difficulty:  Easy

Section:  2.2.B

Learning objective: Chemical Properties of Water

 

 

  1. Phosphoric acid is a polyprotic acid, with pK values of 2.14, 6.86, and 12.38. Which ionic form predominates at pH 9.3?
  2. A) H3PO4
  3. B) H2PO41
  4. C) HPO42
  5. D) PO43
  6. E) none of the above

 

Ans:  C

Level of Difficulty:  Moderate

Section:  2.2.B

Learning objective: Chemical Properties of Water

 

 

  1. To make a phosphate buffer at pH 6.82 starting with one liter of 10 mM phosphoric acid (pKs are 2.15, 6.82, and 12.38), you could add
  2. A) 5 millimoles of HCl.
  3. B) 20 millimoles of K+.
  4. C) 25 millimoles of HCl.
  5. D) 15 millimoles of KOH.
  6. E) You cant make a buffer by adding HCl or KOH.

 

Ans:  E

Level of Difficulty:  Easy

Section:  2.2.C

Learning objective: Chemical Properties of Water

 

  1. You mix equal volumes of 0.05 M NaH2PO4 and 0.05 M Na2HPO4 (pKs for phosphoric acid are 2.15, 6.82 and 12.38). Which of the following best describes the resulting solution?
  2. A) pH 2.15 and poorly buffered
  3. B) pH 2.15 and well buffered
  4. C) pH 6.82 and well buffered
  5. D) pH 12.38 and well buffered
  6. E) pH 6.82 and poorly buffered

 

Ans:  C

Level of Difficulty:  Easy

Section:  2.2.C

Learning objective: Chemical Properties of Water

 

 

  1. To make an acetate buffer at pH 4.76 starting with 500 mL of 0.1 M sodium acetate (pK acetic acid = 4.76), you could add
  2. A) 1 mol of NaOH.
  3. B) 2 mol of HCl.
  4. C) 025 mol of HCl.
  5. D) 1 mol of HCl.
  6. E) You cant make a buffer by adding HCl or NaOH.

 

Ans:  C

Level of Difficulty:  Easy

Section:  2.2.C

Learning objective: Chemical Properties of Water

 

 

  1. 47. The pK1 of citric acid is 3.09. What is the citric acid : monosodium citrate ratio in a 1.0 M citric acid solution with a pH of 2.09?
  2. A) 10:1
  3. B) 1:1
  4. C) 1:10
  5. D) 10:11
  6. E) 1:11

 

Ans:  A

Level of Difficulty:  Easy

Section:  2.2.C

Learning objective: Chemical Properties of Water

 

  1. 48. The pKs of succinic acid are 4.21 and 5.64. How many grams of monosodium succinate (FW = 140 g/mol) and disodium succinate (FW = 162 g/mol) must be added to 1 L of water to produce a solution with a pH 5.28 and a total solute concentration of 100 mM?  (Assume the total volume remains 1 liter, answer in grams monosodium succinate, grams disodium succinate, respectively.)
  2. A) 3 g, 4.2 g
  3. B) 7 g, 4.9 g
  4. C) 9 g, 9.7 g
  5. D) 9 g, 1.1 g
  6. E) 1 g, 14.9 g

 

Ans:  B

Level of Difficulty:  Moderate

Section:  2.2.C

Learning objective: Chemical Properties of Water

 

 

  1. 49. What is the approximate pKa of a weak acid HA if a solution 0.1 M HA and 0.3 M A has a pH of 6.5?
  2. A) 8
  3. B) 0
  4. C) 2
  5. D) 4
  6. E) 6

 

Ans:  B

Level of Difficulty:  Easy

Section:  2.2.C

Learning objective: Chemical Properties of Water

 

  1. A graduate student at SDSU wants to measure the activity of a particular enzyme at pH 4.0. To buffer her reaction, she will use a buffer system based on one of the acids listed below, which acid is most appropriate for the experiment?
  2. A) Formic acid (Ka78 104)
  3. B) MES (Ka13 107)
  4. C) PIPES (Ka74 107)
  5. D) Tris (Ka32 109)
  6. E) Piperidine (Ka58 1012)

 

Ans:  A

Level of Difficulty:  Easy

Section:  2.2.C

Learning objective: Chemical Properties of Water

 

  1. The pH at the midpoint in the titration of an acid with a base is
  2. A) equal to the pK of the corresponding acid.
  3. B) equal to the pK of the corresponding base.
  4. C) equal to 14 minus the pK of the corresponding acid.
  5. D) equal to 14 plus the pK of the corresponding base.
  6. E) none of the above

 

Ans:  A

Level of Difficulty:  Easy

Section:  2.2.C

Learning objective: Chemical Properties of Water

 

 

  1. The capacity of a buffer to resist changes in pH upon addition of protons or hydroxide ions depends on
  2. A) the pKa of the weak acid in the buffer.
  3. B) the pH of the buffer.
  4. C) the total concentration of the weak acid and its conjugate base in the buffer.
  5. D) all of the above
  6. E) none of the above

 

Ans:  D

Level of Difficulty:  Easy

Section:  2.2.C

Learning objective: Chemical Properties of Water

 

 

  1. The pH of blood is affected by
  2. A) the reaction of CO2 with H2O to form carbonic acid.
  3. B) the ionization of aqueous carbonic acid to hydronium ions and the bicarbonate anions.
  4. C) the decrease of the blood pH due to the production of hydronium ions.
  5. D) the excretion of bicarbonate and ammonium ions from the kidneys.
  6. E) all of the above

 

Ans:  E

Level of Difficulty:  Easy

Section:  2.2.C

Learning objective: Chemical Properties of Water

 

Short answer

 

  1. Biological processes can be best understood in the context of water.
  2. What effect does water have on the noncovalent interactions between either charged or polar groups/molecules?
  3. Why is this effect important with respect to biochemical processes?

 

Ans:  a.  Water reduces the strength of those interactions.

  1. Water reduces the strength of polar and ionic interactions. This makes those interactions reversible and life is based on reversible interaction between biomolecules.

Level of Difficulty:  Difficult

Section 2.1.B

Learning objective: Physical Properties of Water

 

 

  1. The hydrophobic effect is an important driving force for protein folding and for the assembly of molecules into cellular structures.
  2. Give the definition of the hydrophobic effect
  3. What are amphiphilic (amphipathic) molecules?
  4. Which cellular structures are composed of many amphipathic molecules that are driven together under the influence of the hydrophobic effect?

 

Ans:  a.  It is defined as the tendency of water to minimize contact with hydrophobic substances.

  1. Molecules with both polar and nonpolar regions
  2. Cellular membranes meet these criteria.

Level of Difficulty:  Moderate

Section 2.1.C

Learning objective: Physical Properties of Water

 

  1. Intracellular fluids and the fluids surrounding cells in multicellular organisms are full of dissolved substances, including nucleotides, amino acids, proteins and ions. The total concentration of substances determines the colligative properties of a fluid.  Osmosis is one of several such colligative properties.
  2. Give the definition of osmosis.
  3. Eukaryotic cells are aqueous solutions surrounded by semipermeable membranes. Consequently, incubation of a cell in a solution of lower osmotic pressure would cause the cell to swell up and burst.  Discuss two solutions that have developed during evolution to solve this problem.

 

Ans:  a.  Osmosis is the movement of solvent (water) through a semipermeable membrane from a region of high concentration to a region of low concentration (with concentration referring to the concentration of water).

  1. Plant cells are surrounded by a rigid cell wall that prevents the cell from expanding and therefore water from flowing into the cell. Animals surround their cells with a solution that has the same osmotic pressure as is found inside their cells.  As a consequence there is no flow of water into or out of these cells.

Level of Difficulty:  Difficult

Section 2.1.D

Learning objective: Physical Properties of Water

 

 

  1. Solutions that contain a mixture of a weak acid and its conjugate base are known to resist changes in pH.
  2. Calculate the pH of 1.0 L of an aqueous solution containing 75 mmol of MES (pKa = 6.09) and 25 mmol of its conjugate base.
  3. How much of a 5.0 M NaOH solution do you need to add to raise the pH to 6.09?

 

Ans:  a.  pH = pKa + log [A]/[HA]

pH = 6.09 + log 25 mM/75 mM = 6.09 0.48 = 5.61

  1. pH = pKa + log [A]/[HA]

At pH = 6.09, 6.09 = 6.09 + log [A]/[HA]

log [A]/[HA] = 0 [A]/[HA] = 1 [A] = [HA]

You know that [A] + [HA] = 100 mM, substitute [A] = [HA] in this equation 2 [A] = 100 mM [A] = [HA] = 50 mM.

You start with 1.0 L of a buffer containing 25 mmol A and 75 mM HA.  To change the pH to 6.09, 25 mmol of HA has to be converted to A.  This is done by adding 25 mmol of NaOH.  The NaOH solution is 5.0 M 25 103 mol/5.0 mol 1.0 L1 = 5.0 103 L or 5.0 mL

Level of Difficulty:  Difficult

Section 2.2.B

Learning objective: Chemical Properties of Water

 

  1. A buffer contains 0.010 mol of lactic acid (pKa = 3.86) and 0.050 mol sodium lactate per liter of aqueous solution.
  2. Calculate the pH of this buffer.
  3. Calculate the pH after 5.0 mL of 0.50 M HCl is added to 1 liter of the buffer (assume the total volume will be 1005 mL).

 

Ans:  a.  pH = pKa + log [A]/[HA]

pH = 3.86 + log 50 mM/10 mM = 3.86 + 0.70 = 4.56

  1. Add 5.0 103 L 0.50 mol/L HCl = 2.5 x 103 mol or 2.5 mmol HCl added

50 mmol lactate + 2.5 mmol H+ = 47.5 mmol lactate + 2.5 mmol lactic acid after adding 2.5 mmol HCl there is 47.5 mmol of lactate and 12.5 mmol of lactic acid pH = 3.86 + log 47.5 mmol (1005 mL)-1/12.5 mmol (1005 mL) 1 = 3.86 + log 47.5/12.5 = 3.86 + 0.58 = 4.44

Level of Difficulty:  Difficult

Section 2.2.B

Learning objective: Chemical Properties of Water

 

 

  1. The pKa of carbonic acid is 6.35. A solution is made by combining 50 mL 1.0 M carbonic acid, 2.0 mL 5.0 M KOH and 448 mL pure water (assume the total volume is 500 mL).  Calculate the pH of the resulting solution.

 

Ans:  50 103 L 1.0 mol/L carbonic acid = 50 103 mol or 50 mmol carbonic acid.  2 103 5.0 mol/L KOH = 10 103 mol or 10 mmol KOH.  50 mmol carbonic acid + 10 mmol OH = 40 mmol carbonic acid and 10 mmol bicarbonate (and 10 mmol water).  pH = pKa + log [A]/[HA] = 6.35 + log 10 mmol (500 mL) 1/40 mmol (500 mL) 1 = 6.35 + log 10/40 = 6.35 0.60 = 5.75

Level of Difficulty:  Difficult

Section 2.2.B

Learning objective: Chemical Properties of Water

 

 

  1. You prepare a solution by mixing 50 mL 0.10 M sodium acetate and 150 mL 1.0 M acetic acid (pKa 4.76).
  2. Calculate the pH of this solution.
  3. Can this solution be used effectively as a buffer (explain your answer)?

 

Ans:  a.  50 103 L 0.10 mol/L acetate = 5.0 103 mol or 5.0 mmol acetate

150 103 1.0 mol/L acetic acid = 150. 103 mol or 150 mmol acetic acid.  The total volume equals 200 mL (assuming additive volumes).

pH = pKa + log [A]/[HA] = 4.76 + log 5 mmol (200 mL) 1/150 mmol (200 mL) 1 = 4.76 + log 5/150 = 4.761.48 = 3.28

  1. No, because the pH (3.28) is more than 1 unit from the pKa (4.76).

Level of Difficulty:  Difficult

Section 2.2.B

Learning objective: Chemical Properties of Water

 

Chapter 4: Amino Acids

 

 

Matching

 

A) glutamate
B) uncharged
C) deprotonated
D) three
E) amino group
F) two
G) C-terminus
H) lysine
I) racemic mixture
J) cysteine
K) zero
L) protonated
M) isoleucine
N) tryptophan
O ) phenylalanine
P) N-terminus

 

 

  1. The net charge of the zwitterion form of Gly is ______.

Ans:  K

 

Section: 4.1.A

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

 

  1. When a peptide bond is formed, an ______ reacts with a carboxylate group.

Ans:  E

 

Section: 4.1.B

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

 

  1. At a pH above its pKa, the phenol group of tyrosine is ______.

Ans:  C

 

Section: 4.1.C

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

  1. In the tripeptide LysProIle, there are ______ charged groups at pH 7.

Ans:  D

 

Section: 4.1.C

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

 

  1. At a pH below its pKa, the e-amino group of lysine is ______.

Ans:  L

 

Section: 4.1.D

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

 

  1. At a pH below its pKa, the b-carboxylate group of Asp is ______.

Ans:  B or L

 

Section: 4.1.D

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

 

  1. In the peptide TrpSerVal, valine is at the ______.

Ans:  G

 

Section: 4.1.E

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

 

  1. In the tripeptide TrpValPhe, the N-terminal residue is ______.

Ans:  N

 

Section: 4.1.E

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

 

  1. In the tripeptide LysProIle, the C-terminal residue is _________.

Ans:  M

 

Section: 4.1.E

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

  1. Biological systems usually produce a single enantiomer, whereas chemical synthesis produces a ______.

Ans:  I

 

Section: 4.2

Level of Difficulty:  Easy

Learning objective:  Stereochemistry

 

  1. GABA is a neurotransmitter derived from ______.

Ans:  A

 

Section: 4.3.B

Level of Difficulty:  Easy

Learning objective:  Amino Acid Derivatives

 

  1. Glutathione is a tripeptide containing a central ______ residue.

Ans:  J

 

Section: 4.3.B

Level of Difficulty:  Easy

Learning objective:  Amino Acid Derivatives

 

Multiple Choice

 

 

  1. In the early 1930s William Rose fed laboratory rats a mixture of all 19 amino acids known to be present in proteins. He observed that his rats lost weight.  This observation led to the discovery of ______ as the 20th amino acid found in proteins.
  2. A) Gly
  3. B) Ala
  4. C) Tyr
  5. D) Asn
  6. E) Thr

 

Ans:  E

Section: 4.1

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

 

  1. What percentage of the 20 amino acids is considered to be nutritionally essential to lab animals?
  2. A) 0%
  3. B) 25%
  4. C) 50%
  5. D) 75%
  6. E) 100%

 

Ans:  C

Section: 4.1

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

 

  1. About half of the 20 amino acids are called essential because
  2. A) they are essential for the synthesis of pyrimidines.
  3. B) they are essential for the synthesis of purines.
  4. C) they are essential for nitrogen metabolism.
  5. D) our bodies need them for protein synthesis.
  6. E) our bodies cannot synthesize them and therefore they need to be present in our diet.

 

Ans:  E

Section: 4.1

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

  1. Which amino acid does not have a primary a-amino group?
  2. A) glutamine
  3. B) arginine
  4. C) lysine
  5. D) proline
  6. E) glutamate

 

Ans:  D

Section: 4.1

Level of Difficulty:  Easy

Learning objective: Amino Acid Structure

 

 

  1. Which of the following statements is true?
  2. A) Amino acids can be derived from purines.
  3. B) Purines and pyrimidines can be derived from amino acids.
  4. C) Corn contains all 20 standard amino acids.
  5. D) Amino acids can be derived from pyrimidines.
  6. E) none of the above

 

Ans:  B

Section: 4.1

Level of Difficulty:  Easy

Learning objective: Amino Acid Structure

 

 

  1. Which of the following amino acids is the least abundant in proteins?
  2. A) V
  3. B) W
  4. C) G
  5. D) F
  6. E) A

 

Ans:  B

Section: 4.1

Level of Difficulty:  Difficult

Learning objective: Amino Acid Structure

 

  1. Zwitterions are
  2. A) amino acids.
  3. B) ionic molecules that are racemic.
  4. C) ions that bear both negatively and positively charged groups.
  5. D) side chain carboxylate anions.
  6. E) delocalized ions.

 

Ans:  C

Section:  4.1.A

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

 

  1. The formation of a dipeptide from two amino acids involves
  2. A) side-chain complementarity.
  3. B) loss of water.
  4. C) oxidation of the a-carbon.
  5. D) reduction of the a-carbon.
  6. E) base catalysis.

 

Ans:  B

Section: 4.1.B

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

  1. The diagram below shows
  2. A) an amino acid.
  3. B) a dipeptide.
  4. C) a tripeptide.
  5. D) a tetrapeptide.
  6. E) a polypeptide.

 

Ans:  D

Section: 4.1.B

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

 

  1. Which of the following amino acids has a charged polar side chain at pH 7.0?
  2. A) Leu
  3. B) Ala
  4. C) Met
  5. D) Trp
  6. E) Glu

 

Ans:  E

Section: 4.1.C

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

  1. Which of the following tripeptides carries a net positive charge at pH 7.0?
  2. A) AlaThrAsn
  3. B) GlnValSer
  4. C) ArgGluMet
  5. D) ProIleLeu
  6. E) LeuLysGly

 

Ans:  E

Section: 4.1.C

Level of Difficulty:  Moderate

Learning objective:  Amino Acid Structure

 

 

  1. Which of the following amino acids has a sulfur atom in its side chain?
  2. A) Asn
  3. B) Ser
  4. C) Phe
  5. D) Met
  6. E) Tyr

 

Ans:  D

Section: 4.1.C

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

 

  1. Which of the following amino acids does not have an ionizable side chain?

 

  1. A) Asp
  2. B) Cys
  3. C) Lys
  4. D) His
  5. E) Asn

 

Ans:  E

Section: 4.1.C

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

  1. Which of the following amino acids has an uncharged polar side chain at pH 7.0?
  2. A) Arg
  3. B) Thr
  4. C) Glu
  5. D) Pro
  6. E) Ile

 

Ans:  B

Section: 4.1.C

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

 

For questions 27 and 28 refer to the diagram below

 

  1. What is the three-letter symbol for the amino acid shown above?
  2. A) Ala
  3. B) Asn
  4. C) Gln
  5. D) Asp
  6. E) Glu

 

Ans:  B

Section: 4.1.C

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

  1. The ionization of amino acids depends on the pH and the pKas of the ionizable groups. The pK1 and pK2 for the amino acid shown above are 2.1 and 8.8, respectively. At what pH is the amino acid ionized predominantly as shown?
  2. A) pH 1.0
  3. B) pH 2.1
  4. C) pH 5.5
  5. D) pH 8.8
  6. E) pH 10.0

 

Ans:  A

Section: 4.1.C

Level of Difficulty:  Easy

Learning objective: Amino Acid Structure

 

 

  1. The pK1, pK2, and pKR for the amino acid arginine are 1.8, 9.0, and 12.5, respectively.  At pH 7.0 arginine would be charged predominantly as follows:
  2. A) a-carboxylate 0, a-amino 0, guanidino +1, net charge +1
  3. B) a-carboxylate +1, a-amino 0, guanidino -1, net charge 0
  4. C) a-carboxylate +1, a-amino 1, guanidino 1, net charge 1
  5. D) a-carboxylate 1, a-amino +1, guanidino +1, net charge +1
  6. E) a-carboxylate 1, a-amino 0, guanidino +1, net charge 0

 

Ans:  D

Section: 4.1.C

Level of Difficulty:  Moderate

Learning objective:  Amino Acid Structure

 

 

  1. The pK1, pK2, and pKR for the amino acid aspartic acid are 2.0, 9.9, and 3.9, respectively. At pH 7.0, aspartic acid would be charged predominantly as follows:
  2. A) a-carboxylate 0, a-amino +1, b-carboxylate 0, net charge +1
  3. B) a-carboxylate 1, a-amino +1, b-carboxylate 1, net charge 1
  4. C) a-carboxylate 0, a-amino 1, b-carboxylate 0, net charge 1
  5. D) a-carboxylate +1, a-amino 1, b-carboxylate +1, net charge +1
  6. E) a-carboxylate +1, a-amino +1, b-carboxylate +1, net charge +3

 

Ans:  B

Section: 4.1.C

Level of Difficulty:  Moderate

Learning objective:  Amino Acid Structure

 

  1. The pK1, pK2, and pKR for the amino acid glutamate are 2.1, 9.5, and 4.1, respectively. At pH 11.0, glutamate would be charged predominantly as follows:
  2. A) a-carboxylate +1, a-amino 0, g-carboxylate +1, net charge +2
  3. B) a-carboxylate 1, a-amino +1, g-carboxylate 1, net charge 1
  4. C) a-carboxylate 0, a-amino 0, g-carboxylate 0, net charge 0
  5. D) a-carboxylate +1, a-amino 1, g-carboxylate +1, net charge +1
  6. E) a-carboxylate 1, a-amino 0, g-carboxylate 1, net charge 2

 

Ans:  E

Section: 4.1.C

Level of Difficulty:  Moderate

Learning objective:  Amino Acid Structure

 

 

  1. The pK1, pK2, and pKR for the amino acid histidine are 1.8, 9.3, and 6.0, respectively. At pH 4.0 would be charged predominantly as follows:
  2. A) a-carboxylate +1, a-amino 0, imidazole 1, net charge 0
  3. B) a-carboxylate 1, a-amino +1, imidazole 0, net charge 0
  4. C) a-carboxylate +1, a-amino +1, imidazole 1, net charge +1
  5. D) a-carboxylate 1, a-amino +1, imidazole +1, net charge +1
  6. E) a-carboxylate 0, a-amino +1, imidazole +1, net charge +2

 

Ans:  D

Section: 4.1.C

Level of Difficulty:  Moderate

Learning objective:  Amino Acid Structure

 

 

  1. The pK1, pK2, and pKR for the amino acid cysteine are 1.9, 10.7, and 8.4, respectively. At pH 5.0, cysteine would be charged predominantly as follows:
  2. A) a-carboxylate 0, a-amino 0, sulfhydryl 0, net charge 0
  3. B) a-carboxylate +1, a-amino 1, sulfhydryl 1, net charge 1
  4. C) a-carboxylate 1, a-amino +1, sulfhydryl +1, net charge +1
  5. D) a-carboxylate 1, a-amino +1, sulfhydryl 0, net charge 0
  6. E) a-carboxylate +1, a-amino 1, sulfhydryl 0, net charge 0

 

Ans:  D

Section: 4.1.C

Level of Difficulty:  Moderate

Learning objective:  Amino Acid Structure

 

  1. The pK1, pK2, and pKR for the amino acid lysine are 2.2, 9.1, and 10.5, respectively. At pH 1.0, lysine would be charged predominantly as follows:
  2. A) a-carboxylate 0, a-amino 1, e-amino 1, net charge 2
  3. B) a-carboxylate 1, a-amino +1, e-amino +1, net charge +1
  4. C) a-carboxylate +1, a-amino +2, e-amino +2, net charge +5
  5. D) a-carboxylate 0, a-amino +1, e-amino +1, net charge +2
  6. E) a-carboxylate +2, a-amino +1, e-amino +1, net charge +4

 

Ans:  D

Section: 4.1.C

Level of Difficulty:  Moderate

Learning objective:  Amino Acid Structure

 

 

Questions 35-37 are based on the diagram shown below.

 

  1. How many amino acid residues are present in the peptide shown above?
  2. A) 1
  3. B) 2
  4. C) 3
  5. D) 4
  6. E) 5

 

Ans:  C

Section: 4.1.C

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

  1. What is the name of the N-terminal amino acid in the peptide shown above?
  2. A) cysteine
  3. B) methionine
  4. C) valine
  5. D) alanine
  6. E) tryptophan

 

Ans:  B

Section: 4.1.C

Level of Difficulty:  Easy

Learning objective: Amino Acid Structure

 

 

  1. What is the three-letter symbol for the C-terminal amino acid in the peptide shown above?
  2. A) Gly
  3. B) Asp
  4. C) Tyr
  5. D) Met
  6. E) Phe

 

Ans:  E

Section: 4.1.C

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

 

  1. While proteins are usually composed of linear chains of amino acids, branched chains of amino acids and internally cross-linked chains can be found in certain proteins. Polypeptide chains are most commonly linked to each other through

 

  1. A) hydrogen bonds.
  2. B) glycosidic bonds.
  3. C) peptide bonds.
  4. D) disulfide bonds.
  5. E) ester linkages.

 

Ans:  D

Section: 4.1.C

Level of Difficulty:  Moderate

Learning objective:  Amino Acid Structure

 

  1. The disulfide bond between two cysteine molecules
  2. A) is a peptide bond.
  3. B) is an ionic interaction that is stable at physiological pH.
  4. C) is a covalent bond formed by oxidation.
  5. D) is a hydrogen bond between the two sulfhydryl groups.
  6. E) is a dipole-dipole interaction.

 

Ans:  C

Section: 4.1.C

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

  1. The two peptides shown in the diagram below are linked through

 

  1. A) a hydrogen bond.
  2. B) a glycosidic bond.
  3. C) a peptide bond.
  4. D) a disulfide bond.
  5. E) an ester linkage.

 

Ans:  D

Section: 4.1.C

Level of Difficulty:  Moderate

Learning objective:  Amino Acid Structure

 

  1. Which one of the representations describes the oligopeptide shown below?

 

  1. A) Tyr-Ala-Thr
  2. B) Tyr-Gly-Cys
  3. C) Tyr-Ala-Ser
  4. D) Phe-Gly-Cys
  5. E) Phe-Ala-Thr

 

Ans:  C

Section: 4.1.C

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

 

  1. The tripeptide glycylarginylglutamate contains four ionizable groups with pKas of 2.1, 4.1 9.8, and 12.5. Calculate the pI for this molecule.

 

  1. A) 1
  2. B) 4
  3. C) 0
  4. D) 3
  5. E) 3

 

Ans:  C

Section: 4.1.D

Level of Difficulty:  Moderate

Learning objective:  Amino Acid Structure

 

  1. The tripeptide alanyllysylaspartate contains four ionizable groups with pKas of 2.0, 3.9, 9.9, and 10.5. Calculate the pI for this molecule.
  2. A) 0
  3. B) 0
  4. C) 2
  5. D) 2
  6. E) none of the above

 

Ans:  E

Section: 4.1.D

Level of Difficulty:  Moderate

Learning objective:  Amino Acid Structure

 

 

  1. The isoelectronic point of an amino acid is the point where
  2. A) the pKa of the a-carboxylic acid is the same as the pKa of the a-amino group.
  3. B) the a-carboxylic acid is protonated and the a-amino group is unprotonated.
  4. C) the solubility of the amino acid is maximized.
  5. D) the a-carboxylic acid and the a-amino group are both half protonated.
  6. E) the amino acid carries no net electrical charge.

 

Ans:  E

Section: 4.1.D

Level of Difficulty:  Moderate

Learning objective:  Amino Acid Structure

 

 

  1. The side-chains of amino acids have
  2. A) a positive charge in every situation.
  3. B) pKas that assure the solubility of every protein.
  4. C) constant pKas no matter what aqueous environment they are found in.
  5. D) different pKas in peptides as compared to the free amino acids
  6. E) polar functional groups.

 

Ans:  D

Section: 4.1.D

Level of Difficulty:  Moderate

Learning objective:  Amino Acid Structure

 

  1. Asx refers to
  2. A) a negatively charged aspartic acid.
  3. B) a positively charged asparagine.
  4. C) a dipeptide containing both aspartic acid and asparagine.
  5. D) either aspartic acid or asparagine.
  6. E) an unnatural amino acid formed during acid hydrolysis of peptide bonds.

 

Ans:  D

Section: 4.1.E

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

 

  1. The peptide AYDG has an N-terminal _________ residue.
  2. A) glycine
  3. B) glutamic acid
  4. C) glutamine
  5. D) aspartic acid
  6. E) alanine

 

Ans:  E

Section: 4.1.E

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

 

  1. Which of the following tripeptides would be expected to be the most hydrophobic?
  2. A) KYG
  3. B) KYA
  4. C) GYA
  5. D) DYA
  6. E) DYG

 

Ans:  C

Section: 4.1.E

Level of Difficulty:  Moderate

Learning objective:  Amino Acid Structure

 

  1. What is the three-letter abbreviation for the peptide valylarginylisoleucine?
  2. A) ValArgIle
  3. B) ValAgnLeu
  4. C) VlnArgIle
  5. D) ValAgnIsl
  6. E) VlnArgLeu

 

Ans:  A

Section: 4.1.E

Level of Difficulty:  Easy

Learning objective:  Amino Acid Structure

 

 

  1. Ribosomes use L amino acids to synthesize proteins. These amino acids are called L because
  2. A) they are chiral.
  3. B) they turn polarized light to the left.
  4. C) they have a configuration of groups around the Ca that can be related to the configuration of groups around the asymmetric carbon in L-glyceraldehyde.
  5. D) they are all (S)-amino acids.
  6. E) they are all (R)-amino acids.

 

Ans:  C

Section: 4.2

Level of Difficulty:  Easy

Learning objective:  Stereochemistry

 

 

  1. Ribosomes use L amino acids to synthesize proteins. These amino acids are called L because
  2. A) they are chiral.
  3. B) they turn polarized light to the left.
  4. C) they are all (S)-amino acids.
  5. D) they are all (R)-amino acids.
  6. E) none of the above

 

Ans:  E

Section: 4.2

Level of Difficulty:  Easy

Learning objective:  Stereochemistry

 

  1. Which of the amino acids represented below has two chiral centers?

 

  1. A) Ala
  2. B) Leu
  3. C) Ile
  4. D) Pro
  5. E) Asn

 

Ans:  C

Section: 4.2

Level of Difficulty:  Difficult

Learning objective:  Stereochemistry

 

 

  1. Which of the five amino acids shown below has 2 chiral centers?

 

Ans:  C

Section: 4.2

Level of Difficulty:  Easy

Learning objective:  Stereochemistry

 

  1. All the standard amino acids except ____ are optically active.
  2. A) Pro
  3. B) Arg
  4. C) Trp
  5. D) Gly
  6. E) Phe

 

Ans:  D

Section: 4.2

Level of Difficulty:  Easy

Learning objective:  Stereochemistry

 

 

  1. The __________ character of most standard amino acids causes solutions of amino acids to rotate the plane of polarized light.
  2. A) chiral
  3. B) zwitterionic
  4. C) polar
  5. D) hydrophobic
  6. E) none of the above

 

Ans:  A

Section: 4.2

Level of Difficulty:  Easy

Learning objective:  Stereochemistry

 

 

  1. All amino acids derived from proteins have the same stereochemical conformation as.
  2. A) L-glyceraldehyde.
  3. B) (R)-alanine.
  4. C) D-glucose.
  5. D) (S)-cysteine.
  6. E)

 

Ans:  A

Section: 4.2

Level of Difficulty:  Moderate

Learning objective: 

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