CHEM 210 Biochemistry Module 1 to 8 Exams' & Final Exam (2025 2026)
Portage Learning Questions and Verified Answers,.
MODULE 1: Water, pH, and Biochemistry Foundations
1. What property of water allows it to act as an effective solvent for ionic
compounds?
A) Low heat capacity
B) Nonpolarity
C) Polarity and hydrogen bonding
D) High viscosity
Answer: C
Rationale: Water’s polarity allows it to surround and stabilize ions via ion-dipole
interactions, facilitating dissolution. The partial negative charge on oxygen
attracts cations while partial positive charges on hydrogens attract anions .
2. What happens to pH when [H⁺] increases tenfold?
A) Increases by 1
B) Decreases by 1
C) Remains constant
,D) Doubles
Answer: B
Rationale: The pH scale is logarithmic (pH = -log[H⁺]). A tenfold increase in
hydrogen ion concentration lowers pH by exactly one unit .
3. What is the conjugate base of H₂CO₃ (carbonic acid)?
A) H₂O
B) HCO₃⁻
C) CO₃²⁻
D) OH⁻
Answer: B
Rationale: Loss of one proton (H⁺) from carbonic acid (H₂CO₃) forms bicarbonate
(HCO₃⁻), which is its conjugate base .
4. Which buffer system is most important in maintaining human blood pH?
A) Phosphate buffer
B) Protein buffer
C) Carbonic acid–bicarbonate buffer
,D) Ammonia buffer
Answer: C
*Rationale: The bicarbonate system (H₂CO₃/HCO₃⁻) maintains blood pH near 7.4
through the reversible equilibrium with CO₂, which is regulated by respiration .*
5. What is the approximate bond angle for a tetrahedral molecular arrangement?
A) 180°
B) 120°
C) 109.5°
D) 107.5°
Answer: C
Rationale: Tetrahedral molecular geometry, as seen in methane (CH₄), has bond
angles of approximately 109.5° .
6. What is the bond angle for a linear molecular shape?
A) 180°
B) 120°
C) 109.5°
, D) 107.5°
Answer: A
Rationale: Linear geometry, as found in carbon dioxide (CO₂), has bond angles of
180° .
7. What element is found in all organic molecules and is considered the
foundation of biochemistry?
A) Oxygen
B) Nitrogen
C) Carbon
D) Hydrogen
Answer: C
Rationale: Carbon has four valence electrons, allowing it to form four stable
covalent bonds, long chains, double/triple bonds, and ring structures. This
versatility makes it essential for all living organisms .
8. True or False: Water can make up 85% of a living organism.
Answer: True
Portage Learning Questions and Verified Answers,.
MODULE 1: Water, pH, and Biochemistry Foundations
1. What property of water allows it to act as an effective solvent for ionic
compounds?
A) Low heat capacity
B) Nonpolarity
C) Polarity and hydrogen bonding
D) High viscosity
Answer: C
Rationale: Water’s polarity allows it to surround and stabilize ions via ion-dipole
interactions, facilitating dissolution. The partial negative charge on oxygen
attracts cations while partial positive charges on hydrogens attract anions .
2. What happens to pH when [H⁺] increases tenfold?
A) Increases by 1
B) Decreases by 1
C) Remains constant
,D) Doubles
Answer: B
Rationale: The pH scale is logarithmic (pH = -log[H⁺]). A tenfold increase in
hydrogen ion concentration lowers pH by exactly one unit .
3. What is the conjugate base of H₂CO₃ (carbonic acid)?
A) H₂O
B) HCO₃⁻
C) CO₃²⁻
D) OH⁻
Answer: B
Rationale: Loss of one proton (H⁺) from carbonic acid (H₂CO₃) forms bicarbonate
(HCO₃⁻), which is its conjugate base .
4. Which buffer system is most important in maintaining human blood pH?
A) Phosphate buffer
B) Protein buffer
C) Carbonic acid–bicarbonate buffer
,D) Ammonia buffer
Answer: C
*Rationale: The bicarbonate system (H₂CO₃/HCO₃⁻) maintains blood pH near 7.4
through the reversible equilibrium with CO₂, which is regulated by respiration .*
5. What is the approximate bond angle for a tetrahedral molecular arrangement?
A) 180°
B) 120°
C) 109.5°
D) 107.5°
Answer: C
Rationale: Tetrahedral molecular geometry, as seen in methane (CH₄), has bond
angles of approximately 109.5° .
6. What is the bond angle for a linear molecular shape?
A) 180°
B) 120°
C) 109.5°
, D) 107.5°
Answer: A
Rationale: Linear geometry, as found in carbon dioxide (CO₂), has bond angles of
180° .
7. What element is found in all organic molecules and is considered the
foundation of biochemistry?
A) Oxygen
B) Nitrogen
C) Carbon
D) Hydrogen
Answer: C
Rationale: Carbon has four valence electrons, allowing it to form four stable
covalent bonds, long chains, double/triple bonds, and ring structures. This
versatility makes it essential for all living organisms .
8. True or False: Water can make up 85% of a living organism.
Answer: True
