Deck 1: The Chemical Foundations of Biochemistry

Question 1

If a reaction at 37 $\degree$ C has a $\Delta$ H of 23 kJ/mol and a $\Delta$ S of 337 J/K.mol, what is the $\Delta$ G for the reaction?

A) 65 kJ/mol
B) -42 kJ/mol
C) 18 kJ/mol
D) -19 kJ/mol
E) none of the above

Answer 1

-19 kJ/mol

Question 2

Consider a reaction in which $\Delta$ H = -20. kJ/mol and $\Delta$ S = 10. J/mol · K.

Answer 2

a. $\Delta$ G = $\Delta$ H - $\Delta$ S $\implies$$\Delta$ G = -20,000 J/mol - (298 × 10 J/mol) = -23,000 J/mol
b. The reaction is spontaneous because the $\Delta$ G is negative.

Question 3

Of the following amino acids, which contains an alcohol?

A) A
B) B
C) C
D) D
E) all of the above

Answer 3

A

Question 4

What functional groups are present in the following molecule?

A) amine and carboxylic acid
B) amine, ketone, and carboxylic acid
C) amine, amide, and carboxylic acid
D) alcohol, amine, amide, and carboxylic acid
E) none of the above are correct

Question 5

K_eq can be determined from the change in standard free energy using the equation ______.

A) K_eq = e^{- $\Delta$ G°/RT}
B) K_eq = ln e^{- $\Delta$ G°/T $\Delta$ S}
C) K_eq = e^{- $\Delta$ H/RT}
D) K_eq = e^{- $\Delta$ G°/T $\Delta$ S}
E) K_eq = log e^{- $\Delta$ G°/RT}

Question 6

Consider the isomerization reaction R $\rightleftarrows$ P, in which R is converted to P. The $\Delta$ G°' for this reaction is -10. kJ/mol. Calculate the [P]/[R] at equilibrium at 25°C.

Question 7

-Which arrow points at a phosphoester bond?

A) A
B) B
C) C
D) D
E) E

Question 8

-Which arrow points at an amide bond?

A) A
B) B
C) C
D) D
E) E

Question 9

-Which arrow points at a phosphoanhydride bond?

A) A
B) B
C) C
D) D
E) E

Question 10

-In a water molecule, hydrogens are partially _____; oxygens are partially _____.

A) negative; negative
B) negative; positive
C) positive; positive
D) positive; negative
E) none of the above

Question 11

Due to the formation of hydrogen bonds, _____ is highly soluble in water.

A) carbon dioxide
B) sodium chloride
C) methanol
D) octane
E) cholesterol

Question 12

Which of the following explains the interactions that occur between the atoms of water molecules and the ions that form when sodium chloride dissolves in water?

A) Hydrogens interact with the sodium ion; oxygens interact with the chloride ion.
B) Hydrogens interact with the chloride ion; oxygens interact with the sodium ion.
C) Hydrogens interact with the sodium ion and the chloride ion.
D) Oxygens interact with the sodium ion and the chloride ion.
E) none of the above

Question 13

The polarity of the O-H bond is caused by the ______ of oxygen relative to that of hydrogen.

Question 14

Which of the following is a physical property of water that results from hydrogen bonding?

A) a high boiling point relative to molecular weight
B) a solid state that is less dense than the liquid state
C) high surface tension
D) the ability to solubilize polar molecules
E) all of the above

Question 15

Which of the following functional groups has two hydrogen bond donors and one hydrogen bond acceptor?

A) alcohol
B) ester
C) thiol
D) amine
E) amide

Question 16

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

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

Question 17

In an aqueous solution, if the [OH^-] is 3.0 × 10^-5 M, what is the [H⁺]?

A) 7.0 × 10^-9
B) 7.0 × 10^-2
C) 3.3 × 10^-3
D) 3.3 × 10^-10
E) none of the above

Question 18

What is the [H⁺] of an aqueous solution with a pH of 6.2?

A) 6.2 × 10^-6
B) 1.6 × 10^-8
C) 6.3 × 10^-7
D) 3. 3 × 10^-5
E) none of the above

Question 19

What would be the resulting pH if one drop (0.05 ml) of 1.0 M HCl was added to one liter of pure water (assume pH 7.0)?

A) 2.7
B) 4.3
C) 5.0
D) 7.0 (there would be no significant change)
E) 9.7

Question 20

What would be the resulting pH if one ml of 1.0 M NaOH was added to one liter of pure water (assume pH 7.0)?

A) 1
B) 3
C) 7.3
D) 11
E) 13

Question 21

Which of the following would be the strongest acid?

A) formic acid, pK = 3.75
B) succinic acid, a diprotic acid with pK = 4.21 and 5.64
C) acetic acid, pK = 4.76
D) ammonium ion, pK = 9.25
E) cannot be determined from the given information

Question 22

What is the pH of a solution that contains three parts acetic acid and one part sodium acetate? The pK for acetic acid is 4.76.

A) 5.24
B) 5.06
C) 4.46
D) 4.28
E) cannot be determined from the given information

Question 23

If the pK values for phosphoric acid are 2.15, 6.82, and 12.38, at what pH would one observe equal amounts of H₂PO₄^- and HPO₄^2-?

A) 2.15
B) 4.49
C) 6.82
D) 9.60
E) 12.38

Question 24

If the pK values for phosphoric acid are 2.15, 6.82 and 12.38, _____ would predominate at pH 5, and _____ would predominate at pH 10.

A) H₃PO₄; H₂PO₄^-
B) H₃PO₄; HPO₄^2-
C) H₃PO₄; PO₄^3-
D) H₂PO₄^-; PO₄^3-
E) H₂PO₄^-; HPO₄^2-

Question 25

What is the conjugate acid of H₂PO₄^-?

A) HPO₄^2-
B) H₂PO₄
C) H₃PO₄
D) PO₄^3-
E) none of the above

Question 26

Which of the following shows the buffer that is found in the bloodstream?

A) H₃PO₄ $\rightleftharpoons$ H₂PO₄^2- + H⁺
B) H₂PO₄^- $\rightleftharpoons$ HPO₄^2- + H⁺
C) HPO₄^2- $\rightleftharpoons$ PO₄^3- + H⁺
D) H₂CO₃ $\rightleftharpoons$ HCO₃^- + H⁺
E) HCO₃^- $\rightleftharpoons$ CO₃^2- + H⁺

Question 27

If a phosphate buffer (pK = 6.82) was formulated such that its pH was 7.3, it would be best suited to buffer against _____. If instead, it was formulated such that its pH was 6.3, it would be best suited to buffer against _____.

A) acid; base
B) acid; acid
C) base; acid
D) base; base
E) a buffer with a pH that far from the pK would not be an effective buffer

Question 28

Metabolic acidosis often causes increased respiratory rates. What portion of the bloodstream buffer is lost through increased respiration?

A) H⁺
B) HCO₃^-
C) H₂CO₃
D) CO₂
E) H₂O