CHEM 210 Biochemistry Module 2
Exam (2024/2025) – Portage Learning
Questions and Verified Answers |
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Multiple-Choice Questions (1–35)
Question 1: What is the primary source of water’s polarity?
A) Covalent bonds
B) Oxygen’s electronegativity
C) Ionic bonds
D) Hydrophobic interactions
Answer: B) Oxygen’s electronegativity
Rationale: Oxygen’s high electronegativity creates a partial negative charge, making water
polar.
Question 2: What type of bond is primarily responsible for water’s cohesive properties?
A) Ionic bond
B) Hydrogen bond
C) Covalent bond
D) Van der Waals forces
Answer: B) Hydrogen bond
Rationale: Hydrogen bonds between water molecules contribute to its cohesion and high surface
tension.
Question 3: What is the pH of a neutral solution at 25°C?
A) 0
B) 7
C) 14
D) 10
Answer: B) 7
Rationale: At 25°C, a neutral solution has equal [H⁺] and [OH⁻], resulting in a pH of 7.
Question 4: Which ion is responsible for acidity in a solution?
A) OH⁻
B) H⁺
C) Na⁺
D) Cl⁻
Answer: B) H⁺
Rationale: Acidity is determined by the concentration of hydrogen ions (H⁺) in a solution.
, Question 5: What is a buffer?
A) A solution that resists pH changes
B) A solution that increases pH
C) A solution that denatures proteins
D) A solution with no ions
Answer: A) A solution that resists pH changes
Rationale: Buffers maintain stable pH by neutralizing added acids or bases.
Question 6: Which acid is a component of the carbonic acid-bicarbonate buffer system?
A) Acetic acid
B) Carbonic acid
C) Hydrochloric acid
D) Phosphoric acid
Answer: B) Carbonic acid
Rationale: Carbonic acid (H₂CO₃) and bicarbonate (HCO₃⁻) form a key physiological buffer
system.
Question 7: What is the pKa of an acid?
A) The pH at which it is fully protonated
B) The pH at which it is half-dissociated
C) The pH at which it is fully deprotonated
D) The pH at which it denatures
Answer: B) The pH at which it is half-dissociated
Rationale: pKa is the pH where [HA] = [A⁻], indicating half-dissociation of the acid.
Question 8: Which property of water allows it to dissolve polar molecules?
A) High heat capacity
B) Polarity
C) Hydrophobic effect
D) Low dielectric constant
Answer: B) Polarity
Rationale: Water’s polarity enables it to interact with and dissolve other polar molecules.
Question 9: What is the Henderson-Hasselbalch equation used for?
A) Calculating molecular weight
B) Determining buffer pH
C) Measuring enzyme activity
D) Assessing protein structure
Answer: B) Determining buffer pH
Rationale: The Henderson-Hasselbalch equation calculates pH based on pKa and the ratio of
conjugate base to acid.
Question 10: Which type of interaction is weakest in biomolecule stabilization?
A) Hydrogen bonds
B) Ionic bonds
C) Van der Waals forces
Exam (2024/2025) – Portage Learning
Questions and Verified Answers |
100% Guarantee Pass
Multiple-Choice Questions (1–35)
Question 1: What is the primary source of water’s polarity?
A) Covalent bonds
B) Oxygen’s electronegativity
C) Ionic bonds
D) Hydrophobic interactions
Answer: B) Oxygen’s electronegativity
Rationale: Oxygen’s high electronegativity creates a partial negative charge, making water
polar.
Question 2: What type of bond is primarily responsible for water’s cohesive properties?
A) Ionic bond
B) Hydrogen bond
C) Covalent bond
D) Van der Waals forces
Answer: B) Hydrogen bond
Rationale: Hydrogen bonds between water molecules contribute to its cohesion and high surface
tension.
Question 3: What is the pH of a neutral solution at 25°C?
A) 0
B) 7
C) 14
D) 10
Answer: B) 7
Rationale: At 25°C, a neutral solution has equal [H⁺] and [OH⁻], resulting in a pH of 7.
Question 4: Which ion is responsible for acidity in a solution?
A) OH⁻
B) H⁺
C) Na⁺
D) Cl⁻
Answer: B) H⁺
Rationale: Acidity is determined by the concentration of hydrogen ions (H⁺) in a solution.
, Question 5: What is a buffer?
A) A solution that resists pH changes
B) A solution that increases pH
C) A solution that denatures proteins
D) A solution with no ions
Answer: A) A solution that resists pH changes
Rationale: Buffers maintain stable pH by neutralizing added acids or bases.
Question 6: Which acid is a component of the carbonic acid-bicarbonate buffer system?
A) Acetic acid
B) Carbonic acid
C) Hydrochloric acid
D) Phosphoric acid
Answer: B) Carbonic acid
Rationale: Carbonic acid (H₂CO₃) and bicarbonate (HCO₃⁻) form a key physiological buffer
system.
Question 7: What is the pKa of an acid?
A) The pH at which it is fully protonated
B) The pH at which it is half-dissociated
C) The pH at which it is fully deprotonated
D) The pH at which it denatures
Answer: B) The pH at which it is half-dissociated
Rationale: pKa is the pH where [HA] = [A⁻], indicating half-dissociation of the acid.
Question 8: Which property of water allows it to dissolve polar molecules?
A) High heat capacity
B) Polarity
C) Hydrophobic effect
D) Low dielectric constant
Answer: B) Polarity
Rationale: Water’s polarity enables it to interact with and dissolve other polar molecules.
Question 9: What is the Henderson-Hasselbalch equation used for?
A) Calculating molecular weight
B) Determining buffer pH
C) Measuring enzyme activity
D) Assessing protein structure
Answer: B) Determining buffer pH
Rationale: The Henderson-Hasselbalch equation calculates pH based on pKa and the ratio of
conjugate base to acid.
Question 10: Which type of interaction is weakest in biomolecule stabilization?
A) Hydrogen bonds
B) Ionic bonds
C) Van der Waals forces
