CHEM 210 Biochemistry Module 1 to 8 Exams & Final Exam
(2025/2026)
Module 1: Water, pH, and Chemical Foundations (Questions 1–30)
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 – Polarity and hydrogen bonding
Rationale: Water’s polarity allows it to surround and stabilize ions. The partial negative charge on
oxygen attracts positive ions (cations), while the partial positive charge on hydrogen attracts negative
ions (anions). This process, called hydration, effectively dissolves ionic compounds. Nonpolar solvents
cannot dissolve ions effectively.
2. What happens to pH when [H⁺] increases tenfold?
- A) Increases by 1
- B) Decreases by 1
- C) Remains constant
- D) Doubles
Answer: B – Decreases by 1
Rationale: Because pH is defined as the negative logarithm of the hydrogen ion concentration (pH = –
log[H⁺]), a tenfold increase in [H⁺] will decrease the pH by exactly one unit. For example, if [H⁺] = 10⁻⁷ M
gives pH 7, a tenfold increase to 10⁻⁶ M gives pH 6.
3. The H⁺ concentration of a solution is 7.9 × 10⁻¹³ M. What is the pH?
- A) 6.70
,- B) –6.70
- C) 12.1
- D) 7.90
Answer: C – 12.1
Rationale: pH = –log(7.9 × 10⁻¹³) ≈ 12.1. This highly basic pH reflects a very low proton concentration.
4. Which of the following is NOT an element typically found in living organisms?
- A) Calcium (Ca)
- B) Hydrogen (H)
- C) Bromine (Br)
- D) Sulfur (S)
- E) Sodium (Na)
Answer: C – Bromine (Br)
Rationale: The most common elements in living organisms are C, H, O, N, P, S, Ca, K, Na, Mg, and Cl.
Bromine is not a common constituent of biomolecules and is considered a trace element not typically
found in significant amounts.
5. A compound with a molecular mass of 3,000 g/mol is considered a macromolecule. (True/False)
Answer: False
Rationale: By definition, a macromolecule typically has a molecular mass greater than 10,000–20,000
g/mol. A mass of 3,000 g/mol would be considered an oligomer or large molecule, but not a true
macromolecule.
6. What molecule is primarily produced via cellular respiration?
- A) DNA
- B) ATP
- C) RNA
,- D) Creatine
Answer: B – ATP
Rationale: Cellular respiration is the process by which cells break down glucose and other organic
molecules to produce adenosine triphosphate (ATP), the primary energy currency of the cell.
7. Scientists refer to ________ as the "super glue" of the chemical world.
- A) Carbon
- B) Oxygen
- C) Nitrogen
- D) Hydrogen
Answer: A – Carbon
Rationale: Carbon is unique because it can form four stable covalent bonds, allowing it to serve as the
central building block for countless complex organic molecules. Carbon skeletons form the backbone of
all biomolecules.
8. Which of the following contributes to water’s unique properties?
- A) Geometry of the molecule
- B) Polarity of the O–H bonds
- C) Ability to form hydrogen bonds
- D) Bond angle of water
- E) All of the above
Answer: E – All of the above
Rationale: Water’s bent molecular geometry, polar O–H bonds, ability to form extensive hydrogen
bonds, and 104.5° bond angle all contribute to its high heat capacity, high surface tension, solvent
properties, and density anomaly.
9. Biomolecules can have only two functional groups. (True/False)
, Answer: False
Rationale: Biomolecules can have multiple functional groups. For example, amino acids contain amine
and carboxyl groups, while many carbohydrates contain hydroxyl, carbonyl, and other groups.
10. In a eukaryotic cell, the organelles called peroxisomes serve the purpose of digesting
macromolecules. (True/False)
Answer: False
Rationale: Peroxisomes are involved in breaking down very long‑chain fatty acids via β‑oxidation and in
detoxifying hydrogen peroxide. Digestion of macromolecules is primarily carried out by lysosomes.
11. For an organic compound, which structure is the most efficient to draw?
- A) Condensed formula
- B) Kekulé structure
- C) Line‑bond (skeletal) structure
- D) Structural formula
Answer: C – Line‑bond (skeletal) structure
Rationale: In a line‑bond structure, carbon atoms are represented as vertices and line segments, and
hydrogen atoms are implied. This is the quickest and clearest way to represent complex organic
molecules.
12. Which of the following is NOT a property of carbon?
- A) Forming ionic bonds
- B) Forming cyclic structures
- C) Forming multiple bonds
- D) Forming bonds with oxygen
- E) Forming in long chains
(2025/2026)
Module 1: Water, pH, and Chemical Foundations (Questions 1–30)
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 – Polarity and hydrogen bonding
Rationale: Water’s polarity allows it to surround and stabilize ions. The partial negative charge on
oxygen attracts positive ions (cations), while the partial positive charge on hydrogen attracts negative
ions (anions). This process, called hydration, effectively dissolves ionic compounds. Nonpolar solvents
cannot dissolve ions effectively.
2. What happens to pH when [H⁺] increases tenfold?
- A) Increases by 1
- B) Decreases by 1
- C) Remains constant
- D) Doubles
Answer: B – Decreases by 1
Rationale: Because pH is defined as the negative logarithm of the hydrogen ion concentration (pH = –
log[H⁺]), a tenfold increase in [H⁺] will decrease the pH by exactly one unit. For example, if [H⁺] = 10⁻⁷ M
gives pH 7, a tenfold increase to 10⁻⁶ M gives pH 6.
3. The H⁺ concentration of a solution is 7.9 × 10⁻¹³ M. What is the pH?
- A) 6.70
,- B) –6.70
- C) 12.1
- D) 7.90
Answer: C – 12.1
Rationale: pH = –log(7.9 × 10⁻¹³) ≈ 12.1. This highly basic pH reflects a very low proton concentration.
4. Which of the following is NOT an element typically found in living organisms?
- A) Calcium (Ca)
- B) Hydrogen (H)
- C) Bromine (Br)
- D) Sulfur (S)
- E) Sodium (Na)
Answer: C – Bromine (Br)
Rationale: The most common elements in living organisms are C, H, O, N, P, S, Ca, K, Na, Mg, and Cl.
Bromine is not a common constituent of biomolecules and is considered a trace element not typically
found in significant amounts.
5. A compound with a molecular mass of 3,000 g/mol is considered a macromolecule. (True/False)
Answer: False
Rationale: By definition, a macromolecule typically has a molecular mass greater than 10,000–20,000
g/mol. A mass of 3,000 g/mol would be considered an oligomer or large molecule, but not a true
macromolecule.
6. What molecule is primarily produced via cellular respiration?
- A) DNA
- B) ATP
- C) RNA
,- D) Creatine
Answer: B – ATP
Rationale: Cellular respiration is the process by which cells break down glucose and other organic
molecules to produce adenosine triphosphate (ATP), the primary energy currency of the cell.
7. Scientists refer to ________ as the "super glue" of the chemical world.
- A) Carbon
- B) Oxygen
- C) Nitrogen
- D) Hydrogen
Answer: A – Carbon
Rationale: Carbon is unique because it can form four stable covalent bonds, allowing it to serve as the
central building block for countless complex organic molecules. Carbon skeletons form the backbone of
all biomolecules.
8. Which of the following contributes to water’s unique properties?
- A) Geometry of the molecule
- B) Polarity of the O–H bonds
- C) Ability to form hydrogen bonds
- D) Bond angle of water
- E) All of the above
Answer: E – All of the above
Rationale: Water’s bent molecular geometry, polar O–H bonds, ability to form extensive hydrogen
bonds, and 104.5° bond angle all contribute to its high heat capacity, high surface tension, solvent
properties, and density anomaly.
9. Biomolecules can have only two functional groups. (True/False)
, Answer: False
Rationale: Biomolecules can have multiple functional groups. For example, amino acids contain amine
and carboxyl groups, while many carbohydrates contain hydroxyl, carbonyl, and other groups.
10. In a eukaryotic cell, the organelles called peroxisomes serve the purpose of digesting
macromolecules. (True/False)
Answer: False
Rationale: Peroxisomes are involved in breaking down very long‑chain fatty acids via β‑oxidation and in
detoxifying hydrogen peroxide. Digestion of macromolecules is primarily carried out by lysosomes.
11. For an organic compound, which structure is the most efficient to draw?
- A) Condensed formula
- B) Kekulé structure
- C) Line‑bond (skeletal) structure
- D) Structural formula
Answer: C – Line‑bond (skeletal) structure
Rationale: In a line‑bond structure, carbon atoms are represented as vertices and line segments, and
hydrogen atoms are implied. This is the quickest and clearest way to represent complex organic
molecules.
12. Which of the following is NOT a property of carbon?
- A) Forming ionic bonds
- B) Forming cyclic structures
- C) Forming multiple bonds
- D) Forming bonds with oxygen
- E) Forming in long chains
