WGU C190: INTRODUCTION TO
BIOLOGY COMPREHENSIVE EXAM
QUESTIONS AND ANSWERS
1. Which of the following describes a phospholipid molecule in a cell membrane?
A. Hydrophilic head and hydrophobic tail
B. Hydrophobic head and hydrophilic tail
C. Completely hydrophobic
D. Completely hydrophilic
Answer: A
Conceptual Explanation: Phospholipids are amphipathic, meaning they have a
hydrophilic (water-loving) phosphate head and hydrophobic (water-fearing) fatty acid
tails, which allows them to form bilayers.
2. What is the primary role of enzymes in metabolic reactions?
A. To provide extra energy to the reaction
B. To raise the activation energy
C. To lower the activation energy
,D. To change the equilibrium constant
Answer: C
Conceptual Explanation: Enzymes act as biological catalysts that speed up chemical
reactions by lowering the activation energy required for the reaction to proceed.
3. Which structure is present in both prokaryotic and eukaryotic cells?
A. Mitochondria
B. Nucleus
C. Ribosomes
D. Endoplasmic reticulum
Answer: C
Conceptual Explanation: Both cell types require ribosomes for protein synthesis, whereas
membrane-bound organelles like the nucleus and mitochondria are exclusive to
eukaryotes.
4. During which phase of cellular respiration is the majority of ATP produced?
A. Glycolysis
B. Citric Acid Cycle
C. Fermentation
D. Oxidative Phosphorylation
, Answer: D
Conceptual Explanation: Oxidative phosphorylation, which includes the electron
transport chain and chemiosmosis, produces approximately 32-34 ATP per glucose
molecule.
5. In DNA replication, which enzyme is responsible for unwinding the double helix?
A. Helicase
B. Ligase
C. DNA Polymerase
D. RNA Primase
Answer: A
Conceptual Explanation: Helicase breaks the hydrogen bonds between the nitrogenous
bases to ‘unzip’ the DNA strands for replication.
6. What is the main purpose of the light-independent reactions (Calvin Cycle) in
photosynthesis?
A. To produce oxygen from water
B. To convert light energy into ATP
C. To release energy from glucose
D. To fix carbon dioxide into organic sugar molecules
Answer: D
BIOLOGY COMPREHENSIVE EXAM
QUESTIONS AND ANSWERS
1. Which of the following describes a phospholipid molecule in a cell membrane?
A. Hydrophilic head and hydrophobic tail
B. Hydrophobic head and hydrophilic tail
C. Completely hydrophobic
D. Completely hydrophilic
Answer: A
Conceptual Explanation: Phospholipids are amphipathic, meaning they have a
hydrophilic (water-loving) phosphate head and hydrophobic (water-fearing) fatty acid
tails, which allows them to form bilayers.
2. What is the primary role of enzymes in metabolic reactions?
A. To provide extra energy to the reaction
B. To raise the activation energy
C. To lower the activation energy
,D. To change the equilibrium constant
Answer: C
Conceptual Explanation: Enzymes act as biological catalysts that speed up chemical
reactions by lowering the activation energy required for the reaction to proceed.
3. Which structure is present in both prokaryotic and eukaryotic cells?
A. Mitochondria
B. Nucleus
C. Ribosomes
D. Endoplasmic reticulum
Answer: C
Conceptual Explanation: Both cell types require ribosomes for protein synthesis, whereas
membrane-bound organelles like the nucleus and mitochondria are exclusive to
eukaryotes.
4. During which phase of cellular respiration is the majority of ATP produced?
A. Glycolysis
B. Citric Acid Cycle
C. Fermentation
D. Oxidative Phosphorylation
, Answer: D
Conceptual Explanation: Oxidative phosphorylation, which includes the electron
transport chain and chemiosmosis, produces approximately 32-34 ATP per glucose
molecule.
5. In DNA replication, which enzyme is responsible for unwinding the double helix?
A. Helicase
B. Ligase
C. DNA Polymerase
D. RNA Primase
Answer: A
Conceptual Explanation: Helicase breaks the hydrogen bonds between the nitrogenous
bases to ‘unzip’ the DNA strands for replication.
6. What is the main purpose of the light-independent reactions (Calvin Cycle) in
photosynthesis?
A. To produce oxygen from water
B. To convert light energy into ATP
C. To release energy from glucose
D. To fix carbon dioxide into organic sugar molecules
Answer: D
