BIO 201 MIDTERM 2026/2027
QUESTIONS WITH CORRECT ANSWERS
(LATEST ), (A+ GUARANTEE).
1. During the process of protein folding, which thermodynamic factor primarily drives the
sequestration of nonpolar side chains into the interior of the protein?
A. The decrease in enthalpy due to the formation of hydrogen bonds
B. The increase in entropy of the surrounding water molecules
C. The decrease in entropy of the polypeptide backbone
D. The formation of disulfide bridges between cysteine residues
Answer: B
Conceptual Explanation: The hydrophobic effect is driven by the release of water
molecules from structured clathrate shells around nonpolar solutes, which significantly
increases the entropy of the solvent (water).
2. In a competitive inhibition model, how are the Vmax and Km of an enzyme-catalyzed
reaction affected?
A. Vmax remains unchanged, and Km increases
B. Vmax decreases, and Km remains unchanged
C. Both Vmax and Km decrease
,D. Vmax remains unchanged, and Km decreases
Answer: A
Conceptual Explanation: In competitive inhibition, the inhibitor competes with the
substrate for the active site. Increasing substrate concentration can overcome inhibition, so
Vmax is unchanged, but more substrate is needed to reach half Vmax, increasing Km.
3. Which component of the cytoskeleton is responsible for the formation of the contractile
ring during cytokinesis in animal cells?
A. Microtubules
B. Intermediate filaments
C. Septins
D. Actin microfilaments
Answer: D
Conceptual Explanation: Actin filaments, along with myosin motor proteins, form the
contractile ring that pinches the cell membrane to divide the cytoplasm during cytokinesis.
4. A researcher observes that a specific transmembrane protein requires ATP to move ions
against their electrochemical gradient. This process is best described as:
A. Facilitated diffusion
B. Simple diffusion
C. Secondary active transport
, D. Primary active transport
Answer: D
Conceptual Explanation: Primary active transport uses chemical energy (like ATP)
directly to pump solutes against their concentration or electrochemical gradient.
5. In the mitochondrial electron transport chain, which complex is responsible for the direct
reduction of molecular oxygen to water?
A. Complex I (NADH Dehydrogenase)
B. Complex IV (Cytochrome c oxidase)
C. Complex III (Cytochrome bc1 complex)
D. Complex II (Succinate Dehydrogenase)
Answer: B
Conceptual Explanation: Complex IV transfers electrons from cytochrome c to oxygen, the
final electron acceptor, which combines with protons to form water.
6. Which of the following events occurs during the Prophase I stage of meiosis but NOT during
mitosis?
A. Condensation of chromatin into chromosomes
B. Formation of the mitotic spindle
C. Synapsis of homologous chromosomes and crossing over
D. Breakdown of the nuclear envelope
QUESTIONS WITH CORRECT ANSWERS
(LATEST ), (A+ GUARANTEE).
1. During the process of protein folding, which thermodynamic factor primarily drives the
sequestration of nonpolar side chains into the interior of the protein?
A. The decrease in enthalpy due to the formation of hydrogen bonds
B. The increase in entropy of the surrounding water molecules
C. The decrease in entropy of the polypeptide backbone
D. The formation of disulfide bridges between cysteine residues
Answer: B
Conceptual Explanation: The hydrophobic effect is driven by the release of water
molecules from structured clathrate shells around nonpolar solutes, which significantly
increases the entropy of the solvent (water).
2. In a competitive inhibition model, how are the Vmax and Km of an enzyme-catalyzed
reaction affected?
A. Vmax remains unchanged, and Km increases
B. Vmax decreases, and Km remains unchanged
C. Both Vmax and Km decrease
,D. Vmax remains unchanged, and Km decreases
Answer: A
Conceptual Explanation: In competitive inhibition, the inhibitor competes with the
substrate for the active site. Increasing substrate concentration can overcome inhibition, so
Vmax is unchanged, but more substrate is needed to reach half Vmax, increasing Km.
3. Which component of the cytoskeleton is responsible for the formation of the contractile
ring during cytokinesis in animal cells?
A. Microtubules
B. Intermediate filaments
C. Septins
D. Actin microfilaments
Answer: D
Conceptual Explanation: Actin filaments, along with myosin motor proteins, form the
contractile ring that pinches the cell membrane to divide the cytoplasm during cytokinesis.
4. A researcher observes that a specific transmembrane protein requires ATP to move ions
against their electrochemical gradient. This process is best described as:
A. Facilitated diffusion
B. Simple diffusion
C. Secondary active transport
, D. Primary active transport
Answer: D
Conceptual Explanation: Primary active transport uses chemical energy (like ATP)
directly to pump solutes against their concentration or electrochemical gradient.
5. In the mitochondrial electron transport chain, which complex is responsible for the direct
reduction of molecular oxygen to water?
A. Complex I (NADH Dehydrogenase)
B. Complex IV (Cytochrome c oxidase)
C. Complex III (Cytochrome bc1 complex)
D. Complex II (Succinate Dehydrogenase)
Answer: B
Conceptual Explanation: Complex IV transfers electrons from cytochrome c to oxygen, the
final electron acceptor, which combines with protons to form water.
6. Which of the following events occurs during the Prophase I stage of meiosis but NOT during
mitosis?
A. Condensation of chromatin into chromosomes
B. Formation of the mitotic spindle
C. Synapsis of homologous chromosomes and crossing over
D. Breakdown of the nuclear envelope
