BIO 171 FINAL PRACTICE EXAM
QUESTIONS AND ANSWERS
1. During DNA replication, which enzyme is responsible for removing the RNA primer and
replacing it with DNA nucleotides?
A. DNA Polymerase III
B. DNA Ligase
C. DNA Polymerase I
D. Helicase
Answer: C
Conceptual Explanation: DNA Polymerase I has 5’ to 3’ exonuclease activity which allows
it to remove RNA primers and replace them with DNA; DNA Polymerase III primarily
elongates the new strand.
2. In the citric acid cycle, the oxidation of one acetyl-CoA molecule results in the production
of how many molecules of NADH?
A. 1
B. 2
C. 4
,D. 3
Answer: D
Conceptual Explanation: For each turn of the Citric Acid Cycle (one acetyl-CoA), three
NAD+ molecules are reduced to NADH at the isocitrate, alpha-ketoglutarate, and malate
dehydrogenase steps.
3. Which of the following best describes the function of the signal recognition particle (SRP)?
A. It catalyzes the formation of peptide bonds in the ribosome.
B. It assists in the folding of cytoplasmic proteins.
C. It marks damaged proteins for degradation by the proteasome.
D. It facilitates the translocation of proteins into the endoplasmic reticulum.
Answer: D
Conceptual Explanation: The SRP binds to the signal peptide of a nascent protein and
targets the entire ribosome-mRNA complex to the ER membrane.
4. In a population at Hardy-Weinberg equilibrium, the frequency of a recessive allele (q) is
0.3. What is the frequency of the heterozygous genotype?
A. 0.09
B. 0.21
C. 0.49
D. 0.42
, Answer: D
Conceptual Explanation: If q = 0.3, then p = 0.7. The heterozygote frequency is 2pq =
2(0.7)(0.3) = 0.42.
5. Which mechanism is primarily responsible for the increase in genetic diversity during
meiosis I?
A. Cytokinesis
B. Sister chromatid separation
C. Semiconservative replication
D. Independent assortment and crossing over
Answer: D
Conceptual Explanation: Crossing over in prophase I and independent assortment in
metaphase I generate new combinations of alleles.
6. What is the primary role of the oxygen consumed during cellular respiration?
A. To act as an acceptor for electrons and hydrogen, forming water
B. To yield energy in the form of ATP as it is passed down the chain
C. To combine with carbon to form CO2
D. To react with glucose to split it into pyruvate
Answer: A
QUESTIONS AND ANSWERS
1. During DNA replication, which enzyme is responsible for removing the RNA primer and
replacing it with DNA nucleotides?
A. DNA Polymerase III
B. DNA Ligase
C. DNA Polymerase I
D. Helicase
Answer: C
Conceptual Explanation: DNA Polymerase I has 5’ to 3’ exonuclease activity which allows
it to remove RNA primers and replace them with DNA; DNA Polymerase III primarily
elongates the new strand.
2. In the citric acid cycle, the oxidation of one acetyl-CoA molecule results in the production
of how many molecules of NADH?
A. 1
B. 2
C. 4
,D. 3
Answer: D
Conceptual Explanation: For each turn of the Citric Acid Cycle (one acetyl-CoA), three
NAD+ molecules are reduced to NADH at the isocitrate, alpha-ketoglutarate, and malate
dehydrogenase steps.
3. Which of the following best describes the function of the signal recognition particle (SRP)?
A. It catalyzes the formation of peptide bonds in the ribosome.
B. It assists in the folding of cytoplasmic proteins.
C. It marks damaged proteins for degradation by the proteasome.
D. It facilitates the translocation of proteins into the endoplasmic reticulum.
Answer: D
Conceptual Explanation: The SRP binds to the signal peptide of a nascent protein and
targets the entire ribosome-mRNA complex to the ER membrane.
4. In a population at Hardy-Weinberg equilibrium, the frequency of a recessive allele (q) is
0.3. What is the frequency of the heterozygous genotype?
A. 0.09
B. 0.21
C. 0.49
D. 0.42
, Answer: D
Conceptual Explanation: If q = 0.3, then p = 0.7. The heterozygote frequency is 2pq =
2(0.7)(0.3) = 0.42.
5. Which mechanism is primarily responsible for the increase in genetic diversity during
meiosis I?
A. Cytokinesis
B. Sister chromatid separation
C. Semiconservative replication
D. Independent assortment and crossing over
Answer: D
Conceptual Explanation: Crossing over in prophase I and independent assortment in
metaphase I generate new combinations of alleles.
6. What is the primary role of the oxygen consumed during cellular respiration?
A. To act as an acceptor for electrons and hydrogen, forming water
B. To yield energy in the form of ATP as it is passed down the chain
C. To combine with carbon to form CO2
D. To react with glucose to split it into pyruvate
Answer: A
