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NWHSU Microbiology Midterm
Questions and Answers (100% Pass)
Which are cellular etiologic agents of infectious disease?
✓ Bacteria, fungi, protozoa, helminths (worms)
Which are a-cellular etiologic agents of infectious disease?
✓ Viruses and prions
Which groups of microorganisms are eukaryotic/prokaryotic?
✓ Eukaryotic: fungi, protozoa, helminths (worms)
✓ Prokaryotae: bacteria
Name major differences between eukaryotic and prokaryotic cells.
✓ Eukaryotic cell: True nucleus, membrane-bound organelles, linear,
complex structure, larger, (Plants and fungi have cell walls) Prokaryotic
cell: Nucleoid, cell wall, no membrane bound organelles, circular DNA,
flagellum
What order of magnitude is the size of a bacterium?
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✓ 10^-6 or 1-10 micro meters
What is the structure and function of glycocalyces, flagella, fimbriae, pili?"
✓ Glycocalyces: polysaccharides, or polysaccharides mixed with proteins
✓ Flagella: protein
✓ Fimbriae: short proteins
✓ Pili: protein tubes
Which of these structures are known virulence factors?
✓ Glycocalyx/capsule
Which structures contribute to biofilm formation?
✓ Glycocalyx (slime layer), fimbrae
Name the various types of flagella arrangements that can be used to identify
bacteria.
✓ Monotrichous (one), amphitrichous (one on both ends), lophotrichous
(tuft), peritrichous (360 degrees)
Which stain makes glycocalyces/capsules visible in the microscope?
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✓ Negative stain
How do spirochetes move?
✓ Corkscrew motion
Name the major components of a gram-positive/gram-negative cell wall.
What is the appearance of gram-positive/gram-negative bacteria?
✓ Gram positive cell wall: Thick layer of peptidoglycan, containing
unique polyalcohols called teichoic acids. Gram stain appearance is
purple. Gram negative cell walls: Thin layer of peptidoglycan, with an
outer membrane containing proteins, and lippolysaccharides. Produce
endotoxins, and appear pink with the Gram stain. The endo toxin is a
lipid A molecule embedded in the outer membrane.
What are the structural features used for identification of bacteria?
✓ Arrangement of flagella, capsule, shape and arrangement of cells,
gram stain, endospores, inclusions, and specific stains
What is the clinical importance of the difference between gram-positive and
gram-negative bacteria?
Master01 | October, 2024/2025 | Latest update
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✓ Gram negative bacteria produce endotoxins (lipid A of
lipopolysaccharides), released when cells die. Some gram positive
(and a few gram negative bacteria) produce exotoxins, which are
released by living cells; some exotoxins cause very severe symptoms.
Gram positive bacteria are susceptible to lysozyme and antibiotics that
interfere with cell-wall biosynthesis, e.g. penicillin, while gram negative
b
✓ acteria are more resistant to lysozyme and penicillin and similar
antibiotics
For which types of bacteria is the acid-fast stain used? Why is it needed?
✓ Organisms with a cell wall that is rich in lipids and waxes. The two
general that are acid fast include Mycobacterium and nocardia. The
acid fast stain is used because the walls are relatively impermeable, so
heat is used to drive the stain into the cell wall. The impermeable wall
also makes these organisms resilient to disinfectants.
How are cytoplasmic membranes of prokaryotes different from those of
eukaryotes?
✓ There's no cholesterol in the prokaryotic (bacteria) membranes
Know the fundamental principles of metabolism (terminology, energy, redox)
Master01 | October, 2024/2025 | Latest update
NWHSU Microbiology Midterm
Questions and Answers (100% Pass)
Which are cellular etiologic agents of infectious disease?
✓ Bacteria, fungi, protozoa, helminths (worms)
Which are a-cellular etiologic agents of infectious disease?
✓ Viruses and prions
Which groups of microorganisms are eukaryotic/prokaryotic?
✓ Eukaryotic: fungi, protozoa, helminths (worms)
✓ Prokaryotae: bacteria
Name major differences between eukaryotic and prokaryotic cells.
✓ Eukaryotic cell: True nucleus, membrane-bound organelles, linear,
complex structure, larger, (Plants and fungi have cell walls) Prokaryotic
cell: Nucleoid, cell wall, no membrane bound organelles, circular DNA,
flagellum
What order of magnitude is the size of a bacterium?
Master01 | October, 2024/2025 | Latest update
, 1|Page | © copyright 2024/2025 | Grade A+
✓ 10^-6 or 1-10 micro meters
What is the structure and function of glycocalyces, flagella, fimbriae, pili?"
✓ Glycocalyces: polysaccharides, or polysaccharides mixed with proteins
✓ Flagella: protein
✓ Fimbriae: short proteins
✓ Pili: protein tubes
Which of these structures are known virulence factors?
✓ Glycocalyx/capsule
Which structures contribute to biofilm formation?
✓ Glycocalyx (slime layer), fimbrae
Name the various types of flagella arrangements that can be used to identify
bacteria.
✓ Monotrichous (one), amphitrichous (one on both ends), lophotrichous
(tuft), peritrichous (360 degrees)
Which stain makes glycocalyces/capsules visible in the microscope?
Master01 | October, 2024/2025 | Latest update
, 1|Page | © copyright 2024/2025 | Grade A+
✓ Negative stain
How do spirochetes move?
✓ Corkscrew motion
Name the major components of a gram-positive/gram-negative cell wall.
What is the appearance of gram-positive/gram-negative bacteria?
✓ Gram positive cell wall: Thick layer of peptidoglycan, containing
unique polyalcohols called teichoic acids. Gram stain appearance is
purple. Gram negative cell walls: Thin layer of peptidoglycan, with an
outer membrane containing proteins, and lippolysaccharides. Produce
endotoxins, and appear pink with the Gram stain. The endo toxin is a
lipid A molecule embedded in the outer membrane.
What are the structural features used for identification of bacteria?
✓ Arrangement of flagella, capsule, shape and arrangement of cells,
gram stain, endospores, inclusions, and specific stains
What is the clinical importance of the difference between gram-positive and
gram-negative bacteria?
Master01 | October, 2024/2025 | Latest update
, 1|Page | © copyright 2024/2025 | Grade A+
✓ Gram negative bacteria produce endotoxins (lipid A of
lipopolysaccharides), released when cells die. Some gram positive
(and a few gram negative bacteria) produce exotoxins, which are
released by living cells; some exotoxins cause very severe symptoms.
Gram positive bacteria are susceptible to lysozyme and antibiotics that
interfere with cell-wall biosynthesis, e.g. penicillin, while gram negative
b
✓ acteria are more resistant to lysozyme and penicillin and similar
antibiotics
For which types of bacteria is the acid-fast stain used? Why is it needed?
✓ Organisms with a cell wall that is rich in lipids and waxes. The two
general that are acid fast include Mycobacterium and nocardia. The
acid fast stain is used because the walls are relatively impermeable, so
heat is used to drive the stain into the cell wall. The impermeable wall
also makes these organisms resilient to disinfectants.
How are cytoplasmic membranes of prokaryotes different from those of
eukaryotes?
✓ There's no cholesterol in the prokaryotic (bacteria) membranes
Know the fundamental principles of metabolism (terminology, energy, redox)
Master01 | October, 2024/2025 | Latest update
