C785 Biochemistry Week 8 Practice Questions 2026 |WGU
1. Which enzyme is responsible for unwinding the DNA double helix during
replication?
A. Helicase
B. DNA Ligase
C. DNA Polymerase
D. Primase
Answer: A
Rationale: Helicase is the enzyme that breaks the hydrogen bonds between the
nitrogenous bases to unwind the DNA double helix.
2. In DNA replication, which enzyme is responsible for sealing the gaps between
Okazaki fragments?
A. Topoisomerase
B. Helicase
C. DNA Ligase
D. RNA Polymerase
Answer: C
Rationale: DNA ligase acts like glue to join DNA strands together by catalyzing the
formation of phosphodiester bonds.
,3. Which molecule carries the genetic information from the DNA in the nucleus
to the ribosome in the cytoplasm?
A. mRNA
B. tRNA
C. rRNA
D. DNA
Answer: A
Rationale: Messenger RNA (mRNA) is transcribed from DNA and carries the code for
protein synthesis to the ribosomes.
4. What is the effect of 2,3-BPG on hemoglobin’s affinity for oxygen?
A. It increases affinity
B. It has no effect
C. It decreases affinity
D. It stabilizes the R-state
Answer: C
Rationale: 2,3-BPG binds to the center of the hemoglobin tetramer, stabilizing the T-state
(low affinity) and promoting oxygen release to tissues.
5. Which of the following describes the ‘Bohr Effect’?
A. Increased oxygen affinity at low pH
B. Decreased oxygen affinity at low pH
C. Decreased oxygen affinity at high pH
D. Increased oxygen affinity in the presence of CO
Answer: B
Rationale: The Bohr Effect states that hemoglobin’s oxygen binding affinity is inversely
related to acidity and the concentration of carbon dioxide.
, 6. Which nitrogenous base is found in RNA but not in DNA?
A. Uracil
B. Thymine
C. Adenine
D. Guanine
Answer: A
Rationale: RNA uses Uracil instead of Thymine, which is found in DNA.
7. What type of bond joins amino acids together in a polypeptide chain?
A. Glycosidic bond
B. Hydrogen bond
C. Ionic bond
D. Peptide bond
Answer: D
Rationale: Peptide bonds are covalent bonds formed between the carboxyl group of one
amino acid and the amino group of another.
8. Where does glycolysis occur in a eukaryotic cell?
A. Mitochondrial matrix
B. Inner mitochondrial membrane
C. Cytosol
D. Nucleus
Answer: C
Rationale: Glycolysis is the anaerobic process of breaking down glucose and takes place in
the cytosol.
1. Which enzyme is responsible for unwinding the DNA double helix during
replication?
A. Helicase
B. DNA Ligase
C. DNA Polymerase
D. Primase
Answer: A
Rationale: Helicase is the enzyme that breaks the hydrogen bonds between the
nitrogenous bases to unwind the DNA double helix.
2. In DNA replication, which enzyme is responsible for sealing the gaps between
Okazaki fragments?
A. Topoisomerase
B. Helicase
C. DNA Ligase
D. RNA Polymerase
Answer: C
Rationale: DNA ligase acts like glue to join DNA strands together by catalyzing the
formation of phosphodiester bonds.
,3. Which molecule carries the genetic information from the DNA in the nucleus
to the ribosome in the cytoplasm?
A. mRNA
B. tRNA
C. rRNA
D. DNA
Answer: A
Rationale: Messenger RNA (mRNA) is transcribed from DNA and carries the code for
protein synthesis to the ribosomes.
4. What is the effect of 2,3-BPG on hemoglobin’s affinity for oxygen?
A. It increases affinity
B. It has no effect
C. It decreases affinity
D. It stabilizes the R-state
Answer: C
Rationale: 2,3-BPG binds to the center of the hemoglobin tetramer, stabilizing the T-state
(low affinity) and promoting oxygen release to tissues.
5. Which of the following describes the ‘Bohr Effect’?
A. Increased oxygen affinity at low pH
B. Decreased oxygen affinity at low pH
C. Decreased oxygen affinity at high pH
D. Increased oxygen affinity in the presence of CO
Answer: B
Rationale: The Bohr Effect states that hemoglobin’s oxygen binding affinity is inversely
related to acidity and the concentration of carbon dioxide.
, 6. Which nitrogenous base is found in RNA but not in DNA?
A. Uracil
B. Thymine
C. Adenine
D. Guanine
Answer: A
Rationale: RNA uses Uracil instead of Thymine, which is found in DNA.
7. What type of bond joins amino acids together in a polypeptide chain?
A. Glycosidic bond
B. Hydrogen bond
C. Ionic bond
D. Peptide bond
Answer: D
Rationale: Peptide bonds are covalent bonds formed between the carboxyl group of one
amino acid and the amino group of another.
8. Where does glycolysis occur in a eukaryotic cell?
A. Mitochondrial matrix
B. Inner mitochondrial membrane
C. Cytosol
D. Nucleus
Answer: C
Rationale: Glycolysis is the anaerobic process of breaking down glucose and takes place in
the cytosol.
