WGU C190 INTRODUCTION TO
BIOLOGY COMPREHENSIVE EXAM
2026/2027 QUESTIONS AND ANSWERS
1. Which property of water allows it to move against gravity in the xylem of plants?
A. High specific heat
B. Expansion upon freezing
C. Universal solvent properties
D. Cohesion and adhesion
Answer: D
Conceptual Explanation: Cohesion (water molecules sticking to each other) and adhesion
(water sticking to other surfaces) work together via capillary action to move water upward
in plants.
2. In a phospholipid bilayer, why do the fatty acid tails point inward?
A. They are hydrophilic and attracted to the cytosol
B. They require direct contact with nucleic acids
C. They are covalently bonded to internal proteins
,D. They are hydrophobic and repelled by water
Answer: D
Conceptual Explanation: Phospholipids are amphipathic; the nonpolar fatty acid tails are
hydrophobic and orient away from the aqueous environment of the extra- and intra-
cellular fluids.
3. Which level of protein structure is characterized by the formation of alpha-helices and
beta-pleated sheets through hydrogen bonding?
A. Primary structure
B. Quaternary structure
C. Tertiary structure
D. Secondary structure
Answer: D
Conceptual Explanation: Secondary structure involves localized folding into helices or
sheets driven by hydrogen bonds between the polypeptide backbone.
4. Which organelle is responsible for the synthesis of lipids and the detoxification of harmful
substances?
A. Rough Endoplasmic Reticulum
B. Golgi Apparatus
C. Lysosome
, D. Smooth Endoplasmic Reticulum
Answer: D
Conceptual Explanation: The Smooth ER lacks ribosomes and is the site for lipid
synthesis, carbohydrate metabolism, and detoxification.
5. What is the primary function of the enzyme DNA Polymerase III during replication?
A. Unwinding the double helix
B. Adding nucleotides to the 3’ end of the growing DNA strand
C. Synthesizing RNA primers
D. Ligating Okazaki fragments together
Answer: B
Conceptual Explanation: DNA Polymerase III adds DNA nucleotides to the 3’ end of the
new strand, requiring a free hydroxyl group to form phosphodiester bonds.
6. In cellular respiration, what is the specific role of oxygen?
A. To provide the carbon source for CO2
B. To facilitate the diffusion of protons into the mitochondrial matrix
C. To catalyze the conversion of glucose to pyruvate
D. To act as the final electron acceptor in the electron transport chain
Answer: D
BIOLOGY COMPREHENSIVE EXAM
2026/2027 QUESTIONS AND ANSWERS
1. Which property of water allows it to move against gravity in the xylem of plants?
A. High specific heat
B. Expansion upon freezing
C. Universal solvent properties
D. Cohesion and adhesion
Answer: D
Conceptual Explanation: Cohesion (water molecules sticking to each other) and adhesion
(water sticking to other surfaces) work together via capillary action to move water upward
in plants.
2. In a phospholipid bilayer, why do the fatty acid tails point inward?
A. They are hydrophilic and attracted to the cytosol
B. They require direct contact with nucleic acids
C. They are covalently bonded to internal proteins
,D. They are hydrophobic and repelled by water
Answer: D
Conceptual Explanation: Phospholipids are amphipathic; the nonpolar fatty acid tails are
hydrophobic and orient away from the aqueous environment of the extra- and intra-
cellular fluids.
3. Which level of protein structure is characterized by the formation of alpha-helices and
beta-pleated sheets through hydrogen bonding?
A. Primary structure
B. Quaternary structure
C. Tertiary structure
D. Secondary structure
Answer: D
Conceptual Explanation: Secondary structure involves localized folding into helices or
sheets driven by hydrogen bonds between the polypeptide backbone.
4. Which organelle is responsible for the synthesis of lipids and the detoxification of harmful
substances?
A. Rough Endoplasmic Reticulum
B. Golgi Apparatus
C. Lysosome
, D. Smooth Endoplasmic Reticulum
Answer: D
Conceptual Explanation: The Smooth ER lacks ribosomes and is the site for lipid
synthesis, carbohydrate metabolism, and detoxification.
5. What is the primary function of the enzyme DNA Polymerase III during replication?
A. Unwinding the double helix
B. Adding nucleotides to the 3’ end of the growing DNA strand
C. Synthesizing RNA primers
D. Ligating Okazaki fragments together
Answer: B
Conceptual Explanation: DNA Polymerase III adds DNA nucleotides to the 3’ end of the
new strand, requiring a free hydroxyl group to form phosphodiester bonds.
6. In cellular respiration, what is the specific role of oxygen?
A. To provide the carbon source for CO2
B. To facilitate the diffusion of protons into the mitochondrial matrix
C. To catalyze the conversion of glucose to pyruvate
D. To act as the final electron acceptor in the electron transport chain
Answer: D
