COMPREHENSIVE UNIVERSITY MICROBIOLOGY & IMMUNOLOGY MCQS
1.
Which component of the bacterial cell is primarily responsible for maintaining cell shape and
preventing osmotic lysis?
A. Plasma membrane
B. Capsule
C. Cell wall
D. Cytoplasm
2.
Gram-positive bacteria retain crystal violet during Gram staining due to:
A. Presence of lipopolysaccharide
B. Thick peptidoglycan layer
C. High lipid content
D. Presence of teichoic acids only
3.
Which staining technique is specifically used to visualize bacterial capsules?
A. Ziehl-Neelsen stain
B. Negative staining
C. Endospore staining
D. Gram staining
4.
The resolving power of a light microscope is primarily limited by:
A. Magnification of the objective lens
B. Wavelength of light used
C. Thickness of the specimen
D. Intensity of illumination
5.
Which of the following structures is NOT found in prokaryotic cells?
A. Ribosomes
B. Nucleoid
C. Mitochondria
D. Plasma membrane
,6.
In acid-fast staining, the primary stain used is:
A. Methylene blue
B. Crystal violet
C. Carbol fuchsin
D. Safranin
7.
Which bacterial structure is most directly involved in attachment to host tissues?
A. Flagella
B. Pili (fimbriae)
C. Endospore
D. Ribosomes
8.
A bacterium that appears pink after Gram staining is likely to have:
A. Thick peptidoglycan
B. No cell wall
C. Outer membrane with lipopolysaccharide
D. High teichoic acid content
9.
Which microscopy technique allows visualization of live, unstained microorganisms with enhanced
contrast?
A. Bright-field microscopy
B. Phase-contrast microscopy
C. Electron microscopy
D. Fluorescence microscopy
10.
The function of bacterial flagella is primarily:
A. Reproduction
B. Protein synthesis
C. Motility
D. DNA replication
,11.
Which of the following is a characteristic of prokaryotic ribosomes?
A. 80S type
B. Membrane-bound
C. 70S type
D. Located in nucleus
12.
During Gram staining, what is the role of iodine?
A. Decolorizer
B. Counterstain
C. Mordant
D. Primary stain
13.
Endospores are best described as:
A. Reproductive structures
B. Dormant survival structures
C. Motility appendages
D. Sites of DNA replication
14.
Which of the following bacteria would be expected to be acid-fast?
A. Escherichia coli
B. Staphylococcus aureus
C. Mycobacterium tuberculosis
D. Bacillus subtilis
15.
What is the primary function of the bacterial capsule?
A. Energy production
B. Protection against phagocytosis
C. Protein synthesis
D. DNA storage
, 16.
The electron microscope differs from the light microscope mainly because it uses:
A. Visible light
B. Electrons instead of light
C. Higher magnification lenses only
D. Fluorescent dyes
17.
Which staining method is used to detect bacterial endospores?
A. Gram staining
B. Acid-fast staining
C. Schaeffer-Fulton method
D. Negative staining
18.
The nucleoid region in bacteria contains:
A. Ribosomal RNA
B. Plasmids only
C. Chromosomal DNA
D. Proteins only
19.
Which factor would increase the resolution of a microscope?
A. Increasing wavelength of light
B. Decreasing numerical aperture
C. Using shorter wavelength light
D. Reducing illumination
20.
Which of the following best explains why Gram-negative bacteria are more resistant to antibiotics?
A. Absence of peptidoglycan
B. Presence of an outer membrane
C. Lack of ribosomes
D. Thicker cytoplasm
21.
A bacterium grows optimally at 37°C but can survive at 20°C and 45°C. It is best classified as:
A. Psychrophile
1.
Which component of the bacterial cell is primarily responsible for maintaining cell shape and
preventing osmotic lysis?
A. Plasma membrane
B. Capsule
C. Cell wall
D. Cytoplasm
2.
Gram-positive bacteria retain crystal violet during Gram staining due to:
A. Presence of lipopolysaccharide
B. Thick peptidoglycan layer
C. High lipid content
D. Presence of teichoic acids only
3.
Which staining technique is specifically used to visualize bacterial capsules?
A. Ziehl-Neelsen stain
B. Negative staining
C. Endospore staining
D. Gram staining
4.
The resolving power of a light microscope is primarily limited by:
A. Magnification of the objective lens
B. Wavelength of light used
C. Thickness of the specimen
D. Intensity of illumination
5.
Which of the following structures is NOT found in prokaryotic cells?
A. Ribosomes
B. Nucleoid
C. Mitochondria
D. Plasma membrane
,6.
In acid-fast staining, the primary stain used is:
A. Methylene blue
B. Crystal violet
C. Carbol fuchsin
D. Safranin
7.
Which bacterial structure is most directly involved in attachment to host tissues?
A. Flagella
B. Pili (fimbriae)
C. Endospore
D. Ribosomes
8.
A bacterium that appears pink after Gram staining is likely to have:
A. Thick peptidoglycan
B. No cell wall
C. Outer membrane with lipopolysaccharide
D. High teichoic acid content
9.
Which microscopy technique allows visualization of live, unstained microorganisms with enhanced
contrast?
A. Bright-field microscopy
B. Phase-contrast microscopy
C. Electron microscopy
D. Fluorescence microscopy
10.
The function of bacterial flagella is primarily:
A. Reproduction
B. Protein synthesis
C. Motility
D. DNA replication
,11.
Which of the following is a characteristic of prokaryotic ribosomes?
A. 80S type
B. Membrane-bound
C. 70S type
D. Located in nucleus
12.
During Gram staining, what is the role of iodine?
A. Decolorizer
B. Counterstain
C. Mordant
D. Primary stain
13.
Endospores are best described as:
A. Reproductive structures
B. Dormant survival structures
C. Motility appendages
D. Sites of DNA replication
14.
Which of the following bacteria would be expected to be acid-fast?
A. Escherichia coli
B. Staphylococcus aureus
C. Mycobacterium tuberculosis
D. Bacillus subtilis
15.
What is the primary function of the bacterial capsule?
A. Energy production
B. Protection against phagocytosis
C. Protein synthesis
D. DNA storage
, 16.
The electron microscope differs from the light microscope mainly because it uses:
A. Visible light
B. Electrons instead of light
C. Higher magnification lenses only
D. Fluorescent dyes
17.
Which staining method is used to detect bacterial endospores?
A. Gram staining
B. Acid-fast staining
C. Schaeffer-Fulton method
D. Negative staining
18.
The nucleoid region in bacteria contains:
A. Ribosomal RNA
B. Plasmids only
C. Chromosomal DNA
D. Proteins only
19.
Which factor would increase the resolution of a microscope?
A. Increasing wavelength of light
B. Decreasing numerical aperture
C. Using shorter wavelength light
D. Reducing illumination
20.
Which of the following best explains why Gram-negative bacteria are more resistant to antibiotics?
A. Absence of peptidoglycan
B. Presence of an outer membrane
C. Lack of ribosomes
D. Thicker cytoplasm
21.
A bacterium grows optimally at 37°C but can survive at 20°C and 45°C. It is best classified as:
A. Psychrophile
