WGU C190 BIOLOGY COMPREHENSIVE
TEST 2027 QUESTIONS AND ANSWERS
1. Which of the following describes the secondary structure of a protein?
A. The linear sequence of amino acids in a polypeptide chain
B. Local folding patterns such as alpha-helices and beta-pleated sheets formed by hydrogen
bonding
C. The three-dimensional folding of a single polypeptide chain due to side chain
interactions
D. The arrangement of multiple polypeptide subunits into a functional complex
Answer: B
Conceptual Explanation: The secondary structure refers to local folded structures that
form within a polypeptide due to interactions between atoms of the backbone, specifically
hydrogen bonds between the carbonyl oxygen and amide hydrogen.
2. In the fluid mosaic model of the cell membrane, what is the primary function of
cholesterol?
A. Facilitating the transport of large polar molecules
,B. Acting as a recognition site for cell-to-cell signaling
C. Regulating membrane fluidity across varying temperatures
D. Providing the structural framework for the attachment of the cytoskeleton
Answer: C
Conceptual Explanation: Cholesterol acts as a fluidity buffer; it prevents the membrane
from becoming too rigid at low temperatures and too fluid at high temperatures.
3. During which phase of the cell cycle does DNA replication occur?
A. S phase
B. G1 phase
C. G2 phase
D. M phase
Answer: A
Conceptual Explanation: The S phase (Synthesis phase) is the part of the cell cycle in
which DNA is replicated, occurring between G1 and G2.
4. Which enzyme is responsible for unwinding the DNA double helix during replication?
A. DNA Polymerase III
B. Primase
C. Ligase
, D. Helicase
Answer: D
Conceptual Explanation: Helicase breaks the hydrogen bonds between the nitrogenous
bases to separate the two strands of DNA for replication.
5. What is the main purpose of the light-independent reactions (Calvin Cycle) in
photosynthesis?
A. To convert solar energy into chemical energy in the form of ATP and NADPH
B. To fix carbon dioxide into organic molecules like G3P
C. To split water molecules and release oxygen as a byproduct
D. To generate a proton gradient across the thylakoid membrane
Answer: B
Conceptual Explanation: The Calvin Cycle uses the ATP and NADPH produced in the light
reactions to fix CO2 into the sugar G3P.
6. In a dihybrid cross between two individuals heterozygous for both traits (AaBb x AaBb),
what is the expected phenotypic ratio?
A. 9:3:3:1
B. 1:2:1
C. 3:1
D. 1:1:1:1
TEST 2027 QUESTIONS AND ANSWERS
1. Which of the following describes the secondary structure of a protein?
A. The linear sequence of amino acids in a polypeptide chain
B. Local folding patterns such as alpha-helices and beta-pleated sheets formed by hydrogen
bonding
C. The three-dimensional folding of a single polypeptide chain due to side chain
interactions
D. The arrangement of multiple polypeptide subunits into a functional complex
Answer: B
Conceptual Explanation: The secondary structure refers to local folded structures that
form within a polypeptide due to interactions between atoms of the backbone, specifically
hydrogen bonds between the carbonyl oxygen and amide hydrogen.
2. In the fluid mosaic model of the cell membrane, what is the primary function of
cholesterol?
A. Facilitating the transport of large polar molecules
,B. Acting as a recognition site for cell-to-cell signaling
C. Regulating membrane fluidity across varying temperatures
D. Providing the structural framework for the attachment of the cytoskeleton
Answer: C
Conceptual Explanation: Cholesterol acts as a fluidity buffer; it prevents the membrane
from becoming too rigid at low temperatures and too fluid at high temperatures.
3. During which phase of the cell cycle does DNA replication occur?
A. S phase
B. G1 phase
C. G2 phase
D. M phase
Answer: A
Conceptual Explanation: The S phase (Synthesis phase) is the part of the cell cycle in
which DNA is replicated, occurring between G1 and G2.
4. Which enzyme is responsible for unwinding the DNA double helix during replication?
A. DNA Polymerase III
B. Primase
C. Ligase
, D. Helicase
Answer: D
Conceptual Explanation: Helicase breaks the hydrogen bonds between the nitrogenous
bases to separate the two strands of DNA for replication.
5. What is the main purpose of the light-independent reactions (Calvin Cycle) in
photosynthesis?
A. To convert solar energy into chemical energy in the form of ATP and NADPH
B. To fix carbon dioxide into organic molecules like G3P
C. To split water molecules and release oxygen as a byproduct
D. To generate a proton gradient across the thylakoid membrane
Answer: B
Conceptual Explanation: The Calvin Cycle uses the ATP and NADPH produced in the light
reactions to fix CO2 into the sugar G3P.
6. In a dihybrid cross between two individuals heterozygous for both traits (AaBb x AaBb),
what is the expected phenotypic ratio?
A. 9:3:3:1
B. 1:2:1
C. 3:1
D. 1:1:1:1
