BIO 171 COMPREHENSIVE BIOLOGY
EXAMINATION 2026/2027
1. Which of the following best describes the movement of a protein destined for secretion,
starting from its synthesis?
A. Rough ER -> Transport vesicle -> Golgi apparatus -> Secretory vesicle -> Plasma
membrane
B. Nucleus -> Smooth ER -> Golgi apparatus -> Secretory vesicle
C. Rough ER -> Golgi apparatus -> Lysosome -> Plasma membrane
D. Free ribosome -> Golgi apparatus -> Rough ER -> Plasma membrane
Answer: A
Conceptual Explanation: Proteins for secretion are synthesized on the rough ER,
transported via vesicles to the Golgi for processing, and then packaged into secretory
vesicles for exocytosis.
2. In a hypertonic solution, what is the primary direction of water movement regarding a
typical animal cell?
A. Net movement of water out of the cell, causing crenation
,B. Net movement of water into the cell, causing lysis
C. Equal movement of water in and out, maintaining dynamic equilibrium
D. Water movement is blocked by the phospholipid bilayer
Answer: A
Conceptual Explanation: A hypertonic solution has a higher solute concentration than the
cytoplasm; water follows its concentration gradient out of the cell, leading to shriveling
(crenation).
3. During the Citric Acid Cycle, which molecule is regenerated to allow the cycle to continue?
A. Citrate
B. Acetyl-CoA
C. Oxaloacetate
D. Succinate
Answer: C
Conceptual Explanation: Oxaloacetate (a 4-carbon molecule) combines with Acetyl-CoA
to form Citrate and is regenerated at the end of the cycle.
4. Which enzyme is responsible for relieving torsional strain (supercoiling) ahead of the
replication fork during DNA synthesis?
A. Helicase
B. DNA Polymerase III
, C. Primase
D. Topoisomerase
Answer: D
Conceptual Explanation: Topoisomerase (or DNA Gyrase in bacteria) breaks and rejoins
DNA strands to relieve the tension caused by unwinding.
5. In Mendelian genetics, a dihybrid cross between two individuals heterozygous for both
traits (AaBb x AaBb) results in what phenotypic ratio, assuming independent assortment?
A. 3:1
B. 1:2:1
C. 1:1:1:1
D. 9:3:3:1
Answer: D
Conceptual Explanation: The 9:3:3:1 ratio represents the combinations of dominant and
recessive phenotypes for two independent genes.
6. Which mechanism is used by C4 plants to minimize photorespiration?
A. Spatially separating carbon fixation from the Calvin cycle in different cells
B. Opening stomata only at night to fix CO2 into organic acids
C. Using Rubisco to fix oxygen when CO2 levels are low
EXAMINATION 2026/2027
1. Which of the following best describes the movement of a protein destined for secretion,
starting from its synthesis?
A. Rough ER -> Transport vesicle -> Golgi apparatus -> Secretory vesicle -> Plasma
membrane
B. Nucleus -> Smooth ER -> Golgi apparatus -> Secretory vesicle
C. Rough ER -> Golgi apparatus -> Lysosome -> Plasma membrane
D. Free ribosome -> Golgi apparatus -> Rough ER -> Plasma membrane
Answer: A
Conceptual Explanation: Proteins for secretion are synthesized on the rough ER,
transported via vesicles to the Golgi for processing, and then packaged into secretory
vesicles for exocytosis.
2. In a hypertonic solution, what is the primary direction of water movement regarding a
typical animal cell?
A. Net movement of water out of the cell, causing crenation
,B. Net movement of water into the cell, causing lysis
C. Equal movement of water in and out, maintaining dynamic equilibrium
D. Water movement is blocked by the phospholipid bilayer
Answer: A
Conceptual Explanation: A hypertonic solution has a higher solute concentration than the
cytoplasm; water follows its concentration gradient out of the cell, leading to shriveling
(crenation).
3. During the Citric Acid Cycle, which molecule is regenerated to allow the cycle to continue?
A. Citrate
B. Acetyl-CoA
C. Oxaloacetate
D. Succinate
Answer: C
Conceptual Explanation: Oxaloacetate (a 4-carbon molecule) combines with Acetyl-CoA
to form Citrate and is regenerated at the end of the cycle.
4. Which enzyme is responsible for relieving torsional strain (supercoiling) ahead of the
replication fork during DNA synthesis?
A. Helicase
B. DNA Polymerase III
, C. Primase
D. Topoisomerase
Answer: D
Conceptual Explanation: Topoisomerase (or DNA Gyrase in bacteria) breaks and rejoins
DNA strands to relieve the tension caused by unwinding.
5. In Mendelian genetics, a dihybrid cross between two individuals heterozygous for both
traits (AaBb x AaBb) results in what phenotypic ratio, assuming independent assortment?
A. 3:1
B. 1:2:1
C. 1:1:1:1
D. 9:3:3:1
Answer: D
Conceptual Explanation: The 9:3:3:1 ratio represents the combinations of dominant and
recessive phenotypes for two independent genes.
6. Which mechanism is used by C4 plants to minimize photorespiration?
A. Spatially separating carbon fixation from the Calvin cycle in different cells
B. Opening stomata only at night to fix CO2 into organic acids
C. Using Rubisco to fix oxygen when CO2 levels are low
