C785 Biochemistry Week 1 Practice Quiz 2026 |WGU
1. Which type of bond is formed between the oxygen atom of one water
molecule and the hydrogen atom of another water molecule?
A. Ionic bond
B. Covalent bond
C. Disulfide bond
D. Hydrogen bond
Answer: D
Rationale: Hydrogen bonds form between the partial positive charge of a hydrogen atom
and the partial negative charge of an oxygen or nitrogen atom in different molecules.
2. What is the primary characteristic of a hydrophobic molecule?
A. It dissolves easily in water
B. It repels water and does not dissolve in it
C. It forms hydrogen bonds with water
D. It carries a strong positive charge
Answer: B
Rationale: Hydrophobic molecules are ‘water-fearing’ and tend to aggregate together
rather than dissolving in polar solvents like water.
,3. Which functional group is characterized by a carbon double-bonded to an
oxygen and single-bonded to a hydroxyl group?
A. Amino group
B. Carboxyl group
C. Carbonyl group
D. Phosphate group
Answer: B
Rationale: A carboxyl group (-COOH) consists of a carbonyl group and a hydroxyl group
attached to the same carbon atom.
4. In the context of pH, a solution with a pH of 3 is how many times more acidic
than a solution with a pH of 5?
A. 2 times
B. 100 times
C. 10 times
D. 1000 times
Answer: B
Rationale: The pH scale is logarithmic; each unit represents a 10-fold difference in H+
concentration. A difference of 2 units (5-3) equals 10 squared, or 100 times.
5. Which level of protein structure is determined solely by the sequence of
amino acids?
A. Secondary structure
B. Primary structure
C. Tertiary structure
D. Quaternary structure
Answer: B
Rationale: Primary structure is the linear sequence of amino acids linked by peptide
bonds.
, 6. Alpha helices and beta-pleated sheets are examples of which level of protein
folding?
A. Primary
B. Quaternary
C. Tertiary
D. Secondary
Answer: D
Rationale: Secondary structure refers to local folding patterns stabilized by hydrogen
bonds between backbone atoms.
7. What type of interaction is primarily responsible for stabilizing the tertiary
structure of a protein?
A. Peptide bonds
B. Interactions between R groups
C. Phosphodiester bonds
D. Glycosidic linkages
Answer: B
Rationale: Tertiary structure is the 3D shape formed by interactions (hydrophobic, ionic,
hydrogen, disulfide) between amino acid side chains (R groups).
8. Which of the following describes an enzyme’s effect on a chemical reaction?
A. It increases the Gibbs free energy
B. It is consumed during the reaction
C. It makes an endergonic reaction exergonic
D. It lowers the activation energy
Answer: D
Rationale: Enzymes act as catalysts by lowering the activation energy barrier, allowing
reactions to proceed faster without changing the overall equilibrium or delta G.
1. Which type of bond is formed between the oxygen atom of one water
molecule and the hydrogen atom of another water molecule?
A. Ionic bond
B. Covalent bond
C. Disulfide bond
D. Hydrogen bond
Answer: D
Rationale: Hydrogen bonds form between the partial positive charge of a hydrogen atom
and the partial negative charge of an oxygen or nitrogen atom in different molecules.
2. What is the primary characteristic of a hydrophobic molecule?
A. It dissolves easily in water
B. It repels water and does not dissolve in it
C. It forms hydrogen bonds with water
D. It carries a strong positive charge
Answer: B
Rationale: Hydrophobic molecules are ‘water-fearing’ and tend to aggregate together
rather than dissolving in polar solvents like water.
,3. Which functional group is characterized by a carbon double-bonded to an
oxygen and single-bonded to a hydroxyl group?
A. Amino group
B. Carboxyl group
C. Carbonyl group
D. Phosphate group
Answer: B
Rationale: A carboxyl group (-COOH) consists of a carbonyl group and a hydroxyl group
attached to the same carbon atom.
4. In the context of pH, a solution with a pH of 3 is how many times more acidic
than a solution with a pH of 5?
A. 2 times
B. 100 times
C. 10 times
D. 1000 times
Answer: B
Rationale: The pH scale is logarithmic; each unit represents a 10-fold difference in H+
concentration. A difference of 2 units (5-3) equals 10 squared, or 100 times.
5. Which level of protein structure is determined solely by the sequence of
amino acids?
A. Secondary structure
B. Primary structure
C. Tertiary structure
D. Quaternary structure
Answer: B
Rationale: Primary structure is the linear sequence of amino acids linked by peptide
bonds.
, 6. Alpha helices and beta-pleated sheets are examples of which level of protein
folding?
A. Primary
B. Quaternary
C. Tertiary
D. Secondary
Answer: D
Rationale: Secondary structure refers to local folding patterns stabilized by hydrogen
bonds between backbone atoms.
7. What type of interaction is primarily responsible for stabilizing the tertiary
structure of a protein?
A. Peptide bonds
B. Interactions between R groups
C. Phosphodiester bonds
D. Glycosidic linkages
Answer: B
Rationale: Tertiary structure is the 3D shape formed by interactions (hydrophobic, ionic,
hydrogen, disulfide) between amino acid side chains (R groups).
8. Which of the following describes an enzyme’s effect on a chemical reaction?
A. It increases the Gibbs free energy
B. It is consumed during the reaction
C. It makes an endergonic reaction exergonic
D. It lowers the activation energy
Answer: D
Rationale: Enzymes act as catalysts by lowering the activation energy barrier, allowing
reactions to proceed faster without changing the overall equilibrium or delta G.
