D311 Microbiology Week 2 Quiz: Microbial Structure and Techniques
2026 |WGU
1. Which component of the Gram-negative cell wall is also known as endotoxin?
A. Lipid A
B. Peptidoglycan
C. Teichoic acid
D. Porins
Answer: A
Rationale: Lipid A is the lipid portion of the lipopolysaccharide (LPS) in the outer
membrane of Gram-negative bacteria and is released as an endotoxin when the cell dies.
2. Which microscope is best for observing the internal structures of a cell in high
detail?
A. Scanning Electron Microscope
B. Phase-Contrast Microscope
C. Transmission Electron Microscope
D. Bright-field Microscope
Answer: C
Rationale: Transmission Electron Microscopy (TEM) passes electrons through a thin
section of the specimen to resolve internal ultra-structures.
3. What is the primary function of bacterial endospores?
A. Reproduction
B. Protein synthesis
C. Storage of nutrients
D. Survival under harsh conditions
Answer: D
,Rationale: Endospores are highly resistant, dormant structures formed by some bacteria
to survive extreme environmental stress.
4. Which staining technique uses Malachite Green as the primary stain?
A. Acid-fast stain
B. Endospore stain
C. Gram stain
D. Capsule stain
Answer: B
Rationale: The Schaeffer-Fulton method for endospore staining uses Malachite Green to
penetrate the spore coat with the help of heat.
5. In a hypertonic solution, a bacterial cell will typically undergo:
A. Osmotic lysis
B. Plasmolysis
C. Equilibrium
D. Binary fission
Answer: B
Rationale: In a hypertonic environment, water leaves the cell, causing the plasma
membrane to shrink away from the cell wall, a process called plasmolysis.
6. Which organelle is responsible for the synthesis of ATP in eukaryotic cells?
A. Golgi complex
B. Lysosomes
C. Mitochondria
D. Ribosomes
Answer: C
Rationale: Mitochondria are the powerhouses of eukaryotic cells where cellular
respiration and ATP production occur.
, 7. What is the total magnification of a microscope with a 10x ocular lens and a
40x objective lens?
A. 50x
B. 40x
C. 1000x
D. 400x
Answer: D
Rationale: Total magnification is calculated by multiplying the magnification of the ocular
lens by the magnification of the objective lens (10 x 40 = 400).
8. The term ‘peritrichous’ refers to which arrangement of flagella?
A. A single flagellum at one end
B. Flagella at both ends of the cell
C. Flagella distributed over the entire cell surface
D. A tuft of flagella at one end
Answer: C
Rationale: Peritrichous bacteria have flagella covering the entire surface of the cell.
9. Which of the following is found in the cell walls of Acid-fast bacteria like
Mycobacterium?
A. Chitin
B. Mycolic acid
C. Cellulose
D. L-form proteins
Answer: B
Rationale: Acid-fast bacteria have a waxy cell wall containing high concentrations of
mycolic acid, which resists standard staining.
2026 |WGU
1. Which component of the Gram-negative cell wall is also known as endotoxin?
A. Lipid A
B. Peptidoglycan
C. Teichoic acid
D. Porins
Answer: A
Rationale: Lipid A is the lipid portion of the lipopolysaccharide (LPS) in the outer
membrane of Gram-negative bacteria and is released as an endotoxin when the cell dies.
2. Which microscope is best for observing the internal structures of a cell in high
detail?
A. Scanning Electron Microscope
B. Phase-Contrast Microscope
C. Transmission Electron Microscope
D. Bright-field Microscope
Answer: C
Rationale: Transmission Electron Microscopy (TEM) passes electrons through a thin
section of the specimen to resolve internal ultra-structures.
3. What is the primary function of bacterial endospores?
A. Reproduction
B. Protein synthesis
C. Storage of nutrients
D. Survival under harsh conditions
Answer: D
,Rationale: Endospores are highly resistant, dormant structures formed by some bacteria
to survive extreme environmental stress.
4. Which staining technique uses Malachite Green as the primary stain?
A. Acid-fast stain
B. Endospore stain
C. Gram stain
D. Capsule stain
Answer: B
Rationale: The Schaeffer-Fulton method for endospore staining uses Malachite Green to
penetrate the spore coat with the help of heat.
5. In a hypertonic solution, a bacterial cell will typically undergo:
A. Osmotic lysis
B. Plasmolysis
C. Equilibrium
D. Binary fission
Answer: B
Rationale: In a hypertonic environment, water leaves the cell, causing the plasma
membrane to shrink away from the cell wall, a process called plasmolysis.
6. Which organelle is responsible for the synthesis of ATP in eukaryotic cells?
A. Golgi complex
B. Lysosomes
C. Mitochondria
D. Ribosomes
Answer: C
Rationale: Mitochondria are the powerhouses of eukaryotic cells where cellular
respiration and ATP production occur.
, 7. What is the total magnification of a microscope with a 10x ocular lens and a
40x objective lens?
A. 50x
B. 40x
C. 1000x
D. 400x
Answer: D
Rationale: Total magnification is calculated by multiplying the magnification of the ocular
lens by the magnification of the objective lens (10 x 40 = 400).
8. The term ‘peritrichous’ refers to which arrangement of flagella?
A. A single flagellum at one end
B. Flagella at both ends of the cell
C. Flagella distributed over the entire cell surface
D. A tuft of flagella at one end
Answer: C
Rationale: Peritrichous bacteria have flagella covering the entire surface of the cell.
9. Which of the following is found in the cell walls of Acid-fast bacteria like
Mycobacterium?
A. Chitin
B. Mycolic acid
C. Cellulose
D. L-form proteins
Answer: B
Rationale: Acid-fast bacteria have a waxy cell wall containing high concentrations of
mycolic acid, which resists standard staining.
