BIO 171 FINAL PRACTICE EXAM
2026/2027 QUESTIONS AND ANSWERS
1. A researcher observes that a specific enzyme’s activity decreases in the presence of an
inhibitor, but the inhibition can be overcome by increasing the substrate concentration. What
type of inhibition is this?
A. Non-competitive inhibition
B. Competitive inhibition
C. Uncompetitive inhibition
D. Allosteric inhibition
Answer: B
Conceptual Explanation: Competitive inhibitors bind to the active site and can be
displaced by a higher concentration of substrate, restoring Vmax.
2. In the process of oxidative phosphorylation, what is the immediate source of energy that
drives ATP synthesis by ATP synthase?
A. The oxidation of glucose to CO2
B. The flow of electrons through the electron transport chain
,C. The H+ concentration gradient across the inner mitochondrial membrane
D. The transfer of phosphate from glycolysis intermediates
Answer: C
Conceptual Explanation: ATP synthase utilizes the proton motive force (H+ gradient)
created by the electron transport chain to catalyze the phosphorylation of ADP.
3. Which of the following best describes the ‘Wobble Hypothesis’ in translation?
A. The movement of the ribosome along the mRNA strand during elongation.
B. The ability of a single tRNA to recognize multiple codons due to flexible base pairing at
the 3rd position.
C. The tendency of RNA polymerase to pause during transcription.
D. The mutation of a stop codon into a sense codon.
Answer: B
Conceptual Explanation: The wobble hypothesis explains why there are fewer tRNAs than
codons; the third base of the codon and the first base of the anticodon can form non-
standard pairs.
4. If a cell has 24 chromosomes at the beginning of G1 phase, how many sister chromatids will
be present during metaphase of mitosis?
A. 48
B. 24
, C. 12
D. 96
Answer: A
Conceptual Explanation: After S phase, each of the 24 chromosomes is replicated into two
sister chromatids, resulting in 48 sister chromatids total.
5. What is the primary function of the Signal Recognition Particle (SRP) in a eukaryotic cell?
A. To direct ribosomes translating specific proteins to the Rough Endoplasmic Reticulum.
B. To facilitate the transport of mRNA out of the nucleus.
C. To degrade misfolded proteins in the cytoplasm.
D. To initiate the process of apoptosis via mitochondrial signaling.
Answer: A
Conceptual Explanation: The SRP binds to the signal peptide of a nascent protein and
docks the ribosome onto the RER membrane.
6. Which mechanism is responsible for the increase in genetic diversity during Meiosis I?
A. Independent assortment of sister chromatids
B. Semiconservative replication of DNA in Interphase
C. The separation of homologous chromosomes during Anaphase II
D. Crossing over between non-sister chromatids of homologous chromosomes
2026/2027 QUESTIONS AND ANSWERS
1. A researcher observes that a specific enzyme’s activity decreases in the presence of an
inhibitor, but the inhibition can be overcome by increasing the substrate concentration. What
type of inhibition is this?
A. Non-competitive inhibition
B. Competitive inhibition
C. Uncompetitive inhibition
D. Allosteric inhibition
Answer: B
Conceptual Explanation: Competitive inhibitors bind to the active site and can be
displaced by a higher concentration of substrate, restoring Vmax.
2. In the process of oxidative phosphorylation, what is the immediate source of energy that
drives ATP synthesis by ATP synthase?
A. The oxidation of glucose to CO2
B. The flow of electrons through the electron transport chain
,C. The H+ concentration gradient across the inner mitochondrial membrane
D. The transfer of phosphate from glycolysis intermediates
Answer: C
Conceptual Explanation: ATP synthase utilizes the proton motive force (H+ gradient)
created by the electron transport chain to catalyze the phosphorylation of ADP.
3. Which of the following best describes the ‘Wobble Hypothesis’ in translation?
A. The movement of the ribosome along the mRNA strand during elongation.
B. The ability of a single tRNA to recognize multiple codons due to flexible base pairing at
the 3rd position.
C. The tendency of RNA polymerase to pause during transcription.
D. The mutation of a stop codon into a sense codon.
Answer: B
Conceptual Explanation: The wobble hypothesis explains why there are fewer tRNAs than
codons; the third base of the codon and the first base of the anticodon can form non-
standard pairs.
4. If a cell has 24 chromosomes at the beginning of G1 phase, how many sister chromatids will
be present during metaphase of mitosis?
A. 48
B. 24
, C. 12
D. 96
Answer: A
Conceptual Explanation: After S phase, each of the 24 chromosomes is replicated into two
sister chromatids, resulting in 48 sister chromatids total.
5. What is the primary function of the Signal Recognition Particle (SRP) in a eukaryotic cell?
A. To direct ribosomes translating specific proteins to the Rough Endoplasmic Reticulum.
B. To facilitate the transport of mRNA out of the nucleus.
C. To degrade misfolded proteins in the cytoplasm.
D. To initiate the process of apoptosis via mitochondrial signaling.
Answer: A
Conceptual Explanation: The SRP binds to the signal peptide of a nascent protein and
docks the ribosome onto the RER membrane.
6. Which mechanism is responsible for the increase in genetic diversity during Meiosis I?
A. Independent assortment of sister chromatids
B. Semiconservative replication of DNA in Interphase
C. The separation of homologous chromosomes during Anaphase II
D. Crossing over between non-sister chromatids of homologous chromosomes
