WGU C785 Biochemistry Exam
2025/2026 – Updated 70 Questions with
100% Correct Answers and Explanations
Question 1
What is the primary function of enzymes in biochemical reactions?
A. Increase the activation energy
B. Lower the activation energy
C. Act as a substrate
D. Store energy
Rationale: Enzymes are biological catalysts that speed up reactions by lowering the
activation energy required for the reaction to proceed. They do not increase activation
energy (A), act as substrates (C), or store energy (D).
Question 2
Which molecule is the primary energy currency of the cell?
A. Glucose
B. ATP
C. NADH
D. FADH2
Rationale: ATP (adenosine triphosphate) is the primary energy currency, providing energy
for cellular processes by releasing a phosphate group. Glucose (A) is an energy source;
NADH (C) and FADH2 (D) are electron carriers.
Question 3
What type of bond stabilizes the secondary structure of proteins?
A. Covalent bonds
B. Ionic bonds
C. Hydrogen bonds
D. Disulfide bonds
,Rationale: Secondary structure (e.g., alpha helices, beta sheets) is stabilized by hydrogen
bonds between backbone atoms. Covalent (A) and disulfide (D) bonds are stronger and
involved in tertiary structure; ionic (B) bonds also contribute to tertiary structure.
Question 4
Which biomolecule is composed of glycerol and three fatty acids?
A. Phospholipid
B. Triglyceride
C. Steroid
D. Wax
Rationale: Triglycerides are lipids formed by one glycerol molecule esterified with three
fatty acids. Phospholipids (A) have two fatty acids and a phosphate group; steroids (C)
have a four-ring structure; waxes (D) are esters of long-chain alcohols and fatty acids.
Question 5
What is the primary source of energy for glycolysis?
A. Glucose
B. Pyruvate
C. Acetyl-CoA
D. Fructose
Rationale: Glycolysis breaks down glucose into pyruvate, producing ATP. Pyruvate (B) is a
product; acetyl-CoA (C) enters the citric acid cycle; fructose (D) is an intermediate in
glycolysis.
Question 6
Which enzyme catalyzes the conversion of pyruvate to lactate under anaerobic conditions?
A. Pyruvate kinase
B. Lactate dehydrogenase
C. Pyruvate decarboxylase
D. Hexokinase
Rationale: Lactate dehydrogenase converts pyruvate to lactate, regenerating NAD+ for
glycolysis in anaerobic conditions. Pyruvate kinase (A) is in glycolysis; pyruvate
decarboxylase (C) in fermentation (yeast); hexokinase (D) phosphorylates glucose.
, Question 7
What is the primary role of DNA in cells?
A. Catalyze reactions
B. Transport oxygen
C. Store genetic information
D. Provide structural support
Rationale: DNA stores genetic information for protein synthesis and heredity. Catalysis (A)
is by enzymes; oxygen transport (B) by hemoglobin; structural support (D) by proteins like
collagen.
Question 8
Which type of RNA carries amino acids to the ribosome during protein synthesis?
A. mRNA
B. rRNA
C. tRNA
D. siRNA
Rationale: tRNA (transfer RNA) carries amino acids to the ribosome, matching codons to
anticodons. mRNA (A) carries genetic code; rRNA (B) forms ribosomes; siRNA (D)
regulates gene expression.
Question 9
What is the final electron acceptor in the electron transport chain?
A. NAD+
B. FAD
C. Oxygen
D. Glucose
Rationale: Oxygen accepts electrons in the electron transport chain, forming water. NAD+
(A) and FAD (B) are electron carriers; glucose (D) is a glycolysis substrate.
Question 10
2025/2026 – Updated 70 Questions with
100% Correct Answers and Explanations
Question 1
What is the primary function of enzymes in biochemical reactions?
A. Increase the activation energy
B. Lower the activation energy
C. Act as a substrate
D. Store energy
Rationale: Enzymes are biological catalysts that speed up reactions by lowering the
activation energy required for the reaction to proceed. They do not increase activation
energy (A), act as substrates (C), or store energy (D).
Question 2
Which molecule is the primary energy currency of the cell?
A. Glucose
B. ATP
C. NADH
D. FADH2
Rationale: ATP (adenosine triphosphate) is the primary energy currency, providing energy
for cellular processes by releasing a phosphate group. Glucose (A) is an energy source;
NADH (C) and FADH2 (D) are electron carriers.
Question 3
What type of bond stabilizes the secondary structure of proteins?
A. Covalent bonds
B. Ionic bonds
C. Hydrogen bonds
D. Disulfide bonds
,Rationale: Secondary structure (e.g., alpha helices, beta sheets) is stabilized by hydrogen
bonds between backbone atoms. Covalent (A) and disulfide (D) bonds are stronger and
involved in tertiary structure; ionic (B) bonds also contribute to tertiary structure.
Question 4
Which biomolecule is composed of glycerol and three fatty acids?
A. Phospholipid
B. Triglyceride
C. Steroid
D. Wax
Rationale: Triglycerides are lipids formed by one glycerol molecule esterified with three
fatty acids. Phospholipids (A) have two fatty acids and a phosphate group; steroids (C)
have a four-ring structure; waxes (D) are esters of long-chain alcohols and fatty acids.
Question 5
What is the primary source of energy for glycolysis?
A. Glucose
B. Pyruvate
C. Acetyl-CoA
D. Fructose
Rationale: Glycolysis breaks down glucose into pyruvate, producing ATP. Pyruvate (B) is a
product; acetyl-CoA (C) enters the citric acid cycle; fructose (D) is an intermediate in
glycolysis.
Question 6
Which enzyme catalyzes the conversion of pyruvate to lactate under anaerobic conditions?
A. Pyruvate kinase
B. Lactate dehydrogenase
C. Pyruvate decarboxylase
D. Hexokinase
Rationale: Lactate dehydrogenase converts pyruvate to lactate, regenerating NAD+ for
glycolysis in anaerobic conditions. Pyruvate kinase (A) is in glycolysis; pyruvate
decarboxylase (C) in fermentation (yeast); hexokinase (D) phosphorylates glucose.
, Question 7
What is the primary role of DNA in cells?
A. Catalyze reactions
B. Transport oxygen
C. Store genetic information
D. Provide structural support
Rationale: DNA stores genetic information for protein synthesis and heredity. Catalysis (A)
is by enzymes; oxygen transport (B) by hemoglobin; structural support (D) by proteins like
collagen.
Question 8
Which type of RNA carries amino acids to the ribosome during protein synthesis?
A. mRNA
B. rRNA
C. tRNA
D. siRNA
Rationale: tRNA (transfer RNA) carries amino acids to the ribosome, matching codons to
anticodons. mRNA (A) carries genetic code; rRNA (B) forms ribosomes; siRNA (D)
regulates gene expression.
Question 9
What is the final electron acceptor in the electron transport chain?
A. NAD+
B. FAD
C. Oxygen
D. Glucose
Rationale: Oxygen accepts electrons in the electron transport chain, forming water. NAD+
(A) and FAD (B) are electron carriers; glucose (D) is a glycolysis substrate.
Question 10
