BIOC 384 - D2Q 1-3 Miesfeld Questions And Correct
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New Update 2026
Question 1. Which TWO of the following processes are driven by the hydrophobic
effect?
1. Dissolving sodium chloride in water
2. Sequestration of hydrophobic groups to the interior of a folded protein
3. Dissolving oil in water
4. Separation of oil and water
A. 1 and 3
B. 2 and 4
C. 1 and 4
D. 2 and 3
Correct Answer: B
Rationale: The hydrophobic effect is driven by the tendency of nonpolar molecules to
aggregate in aqueous solution to minimize the disruption of water structure and
maximize entropy. Sequestration of hydrophobic groups to a protein interior (2) and
separation of oil and water (4) are classic examples .
Question 2. What type of solution should erythrocytes (red blood cells) be stored in to
prevent damage?
A. Hypotonic solution
B. Hypertonic solution
C. Isotonic solution
D. Solution at the same pH
Correct Answer: C
, Rationale: Erythrocytes should be stored in an isotonic solution to prevent osmotic
damage. A hypotonic solution would cause water to enter the cells, leading to lysis
(bursting). A hypertonic solution would cause water to leave the cells, leading to
crenation (shriveling) . An isotonic solution has the same solute concentration as the
intracellular fluid, maintaining cell integrity .
Question 3. The evolution of antifreeze proteins is an example of proteins that are:
A. Similar in function and similar in structure
B. Different in structure, but similar in function
C. Different in function, but similar in structure
D. Different in structure and different in function
Correct Answer: B
Rationale: Antifreeze proteins in different organisms have evolved independently to
perform the same function (preventing ice crystal formation) but have different
structures. This is a classic example of convergent evolution where proteins with
different structures have similar functions .
Question 4. A titratable group is in the active site of an enzyme and must be
protonated for the enzyme to function. Assume that the group has a pKa of 6.5 and that
the activity is proportional to the fraction of molecules in the protonated state. Which
FOUR of the following statements are true?
1. At pH 9.0 close to 100% of the enzyme molecules are active.
2. At pH 6.8 the enzyme is 66.6% inactive.
3. At pH 6.5 the enzyme is 50% active.
4. At pH 7.2 there are about 5 inactive enzymes for every active enzyme.
5. At pH 9.0 close to 100% of the enzyme molecules are inactive.
A. 1, 2, 3, and 4
B. 2, 3, 4, and 5
C. 1, 2, 4, and 5
D. 1, 3, 4, and 5
, Correct Answer: B
Rationale: Using the Henderson-Hasselbalch equation: pH = pKa + log([A-]/[HA]). The
group must be protonated (HA) to be active.
• At pH 6.5, [A-]/[HA] = 1, so 50% active (statement 3 is true).
• At pH 6.8, [A-]/[HA] = 10^0.3 = 2, so HA fraction = 1/3 = 33.3% active, 66.7% inactive
(statement 2 is true).
• At pH 7.2, [A-]/[HA] = 10^0.7 = 5, so for every 1 active (HA), there are 5 inactive (A-)
(statement 4 is true).
• At pH 9.0, the group is essentially fully deprotonated, so close to 100% inactive
(statement 5 is true, statement 1 is false) .
Question 5. Which of the following equations correctly describes the equilibrium
constant (Keq) for the reaction: aA + bB ⇌ cC + dD?
A. Keq = c[C]d[D] / a[A]b[B]
B. Keq = [C]^c[D]^d / [A]^a[B]^b
C. Keq = [A]^a[B]^b / [C]^c[D]^d
D. Keq = ΔG°' = -RT log ΔG
Correct Answer: B
Rationale: The equilibrium constant (Keq) for the reaction aA + bB ⇌ cC + dD is the
ratio of the product of the product concentrations raised to their stoichiometric
coefficients to the product of the reactant concentrations raised to their stoichiometric
coefficients: Keq = [C]^c[D]^d / [A]^a[B]^b .
Question 6. For the reaction A + B ⇌ C + D, which of the following is correct?
A. Keq = [A][B] / [C][D]
B. Keq = [C][D] / [A][B]
C. ΔG° = -RT log Keq
D. ΔG° = RT ln Keq
Correct Answer: B
, Rationale: For the reaction A + B ⇌ C + D, the equilibrium constant is Keq = [C][D] /
[A][B]. The relationship between the standard free energy change and the equilibrium
constant is ΔG° = -RT ln Keq .
Question 7. In aerobic respiration, the reductant (reducing agent) is and
the oxidant (oxidizing agent) is with carbon dioxide being one of the
products and being the other product. The conversion of
energy to chemical energy generates ATP for use in metabolism.
A. glucose; oxygen; water; redox
B. oxygen; glucose; water; metabolic
C. glucose; carbon dioxide; water; redox
D. oxygen; carbon dioxide; water; chemical
Correct Answer: A
Rationale: In aerobic respiration, glucose is the reductant (loses electrons, is oxidized),
and oxygen is the oxidant (gains electrons, is reduced). The products are carbon dioxide
and water. The conversion of redox energy (from electron transfer) to chemical energy
(ATP) drives metabolism .
Question 8. Which TWO of the following statements most accurately describe the
difference between the actual change in free energy (ΔG) and the standard change in
free energy (ΔG°)?
1. The actual change in free energy is dependent on temperature whereas the standard
change in free energy is dependent on pressure but not temperature.
2. The standard change in free energy reflects the potential energy in reactants and
products independent of concentration whereas the actual change in free energy is
dependent on the concentration of reactants and products under steady state
conditions.
3. The standard change of free energy is a function of time whereas the actual change in
free energy is a function of the rate constant.
4. The actual change in free energy changes in response to the environment whereas the
standard change in free energy is a constant for a given reaction.
Answers (Verified Answers) | Already Graded A+ |
New Update 2026
Question 1. Which TWO of the following processes are driven by the hydrophobic
effect?
1. Dissolving sodium chloride in water
2. Sequestration of hydrophobic groups to the interior of a folded protein
3. Dissolving oil in water
4. Separation of oil and water
A. 1 and 3
B. 2 and 4
C. 1 and 4
D. 2 and 3
Correct Answer: B
Rationale: The hydrophobic effect is driven by the tendency of nonpolar molecules to
aggregate in aqueous solution to minimize the disruption of water structure and
maximize entropy. Sequestration of hydrophobic groups to a protein interior (2) and
separation of oil and water (4) are classic examples .
Question 2. What type of solution should erythrocytes (red blood cells) be stored in to
prevent damage?
A. Hypotonic solution
B. Hypertonic solution
C. Isotonic solution
D. Solution at the same pH
Correct Answer: C
, Rationale: Erythrocytes should be stored in an isotonic solution to prevent osmotic
damage. A hypotonic solution would cause water to enter the cells, leading to lysis
(bursting). A hypertonic solution would cause water to leave the cells, leading to
crenation (shriveling) . An isotonic solution has the same solute concentration as the
intracellular fluid, maintaining cell integrity .
Question 3. The evolution of antifreeze proteins is an example of proteins that are:
A. Similar in function and similar in structure
B. Different in structure, but similar in function
C. Different in function, but similar in structure
D. Different in structure and different in function
Correct Answer: B
Rationale: Antifreeze proteins in different organisms have evolved independently to
perform the same function (preventing ice crystal formation) but have different
structures. This is a classic example of convergent evolution where proteins with
different structures have similar functions .
Question 4. A titratable group is in the active site of an enzyme and must be
protonated for the enzyme to function. Assume that the group has a pKa of 6.5 and that
the activity is proportional to the fraction of molecules in the protonated state. Which
FOUR of the following statements are true?
1. At pH 9.0 close to 100% of the enzyme molecules are active.
2. At pH 6.8 the enzyme is 66.6% inactive.
3. At pH 6.5 the enzyme is 50% active.
4. At pH 7.2 there are about 5 inactive enzymes for every active enzyme.
5. At pH 9.0 close to 100% of the enzyme molecules are inactive.
A. 1, 2, 3, and 4
B. 2, 3, 4, and 5
C. 1, 2, 4, and 5
D. 1, 3, 4, and 5
, Correct Answer: B
Rationale: Using the Henderson-Hasselbalch equation: pH = pKa + log([A-]/[HA]). The
group must be protonated (HA) to be active.
• At pH 6.5, [A-]/[HA] = 1, so 50% active (statement 3 is true).
• At pH 6.8, [A-]/[HA] = 10^0.3 = 2, so HA fraction = 1/3 = 33.3% active, 66.7% inactive
(statement 2 is true).
• At pH 7.2, [A-]/[HA] = 10^0.7 = 5, so for every 1 active (HA), there are 5 inactive (A-)
(statement 4 is true).
• At pH 9.0, the group is essentially fully deprotonated, so close to 100% inactive
(statement 5 is true, statement 1 is false) .
Question 5. Which of the following equations correctly describes the equilibrium
constant (Keq) for the reaction: aA + bB ⇌ cC + dD?
A. Keq = c[C]d[D] / a[A]b[B]
B. Keq = [C]^c[D]^d / [A]^a[B]^b
C. Keq = [A]^a[B]^b / [C]^c[D]^d
D. Keq = ΔG°' = -RT log ΔG
Correct Answer: B
Rationale: The equilibrium constant (Keq) for the reaction aA + bB ⇌ cC + dD is the
ratio of the product of the product concentrations raised to their stoichiometric
coefficients to the product of the reactant concentrations raised to their stoichiometric
coefficients: Keq = [C]^c[D]^d / [A]^a[B]^b .
Question 6. For the reaction A + B ⇌ C + D, which of the following is correct?
A. Keq = [A][B] / [C][D]
B. Keq = [C][D] / [A][B]
C. ΔG° = -RT log Keq
D. ΔG° = RT ln Keq
Correct Answer: B
, Rationale: For the reaction A + B ⇌ C + D, the equilibrium constant is Keq = [C][D] /
[A][B]. The relationship between the standard free energy change and the equilibrium
constant is ΔG° = -RT ln Keq .
Question 7. In aerobic respiration, the reductant (reducing agent) is and
the oxidant (oxidizing agent) is with carbon dioxide being one of the
products and being the other product. The conversion of
energy to chemical energy generates ATP for use in metabolism.
A. glucose; oxygen; water; redox
B. oxygen; glucose; water; metabolic
C. glucose; carbon dioxide; water; redox
D. oxygen; carbon dioxide; water; chemical
Correct Answer: A
Rationale: In aerobic respiration, glucose is the reductant (loses electrons, is oxidized),
and oxygen is the oxidant (gains electrons, is reduced). The products are carbon dioxide
and water. The conversion of redox energy (from electron transfer) to chemical energy
(ATP) drives metabolism .
Question 8. Which TWO of the following statements most accurately describe the
difference between the actual change in free energy (ΔG) and the standard change in
free energy (ΔG°)?
1. The actual change in free energy is dependent on temperature whereas the standard
change in free energy is dependent on pressure but not temperature.
2. The standard change in free energy reflects the potential energy in reactants and
products independent of concentration whereas the actual change in free energy is
dependent on the concentration of reactants and products under steady state
conditions.
3. The standard change of free energy is a function of time whereas the actual change in
free energy is a function of the rate constant.
4. The actual change in free energy changes in response to the environment whereas the
standard change in free energy is a constant for a given reaction.
