MBIO 3401 QUESTIONS AND ANSWERS 2026
What are the 4 traits of a microbe? - Answers - -Too small to be seen by human eye
-Grow and reproduce in nature
-Active metabolism
-Respond to stimuli
Diameter of a typical microbe? - Answers - 0.2 micrometers (μm) in diameter
Who was the first person to observe single-celled microbes? - Answers - Antonie van
Leeuwenhoek
Where do microbes come from? - Answers - they have parents
who disproved theory of spontaneous generation? - Answers - Louis Pasteur
Louis Pasteur contribution to microbiology? - Answers - disproved spontaneous
generation
Who proved the link between microbes and infectious disease? - Answers - Robert
Koch
Robert Koch's contribution to microbiology? - Answers - Link between microbes and
infectious disease.
What are the two primary types of cells? - Answers - Prokaryotic and Eukaryotic
Is bacteria prokaryotic or eukaryotic? - Answers - Prokaryotic
Is archaea prokaryotic or eukaryotic? - Answers - Prokaryotic
Primary purpose of light microscope? - Answers - Improve contrast and resolution
What is contrast? - Answers - the difference in brightness between the light and dark
areas of an image
What is resolution of an image? - Answers - Ability to distinguish between two objects.
5 types of light microscopy? - Answers - -Bright Field
-Phase contrast
-Differential Interference Contrast
-Dark-field
,-Fluorescence
Color of Gram + cells after gram stain? - Answers - Purple
Color of gram - cells after gram stain - Answers - Red/pink
What is confocal scanning laser microscopy? - Answers - A computerized fluorescent
microscope that uses a laser source to create a 3D image
Pros and Cons of Bright-field microscopy: - Answers - Pros: Simple and affordable
Cons: need staining and difficult to see small/colorless cells
Pros and Cons of dark field microscopy: - Answers - Pros: Highly sensitive for small
cells/structures
Cons: poor resolution and prone to artifacts
Pros and Cons of Phase contrast microscopy and differential interference microscopy: -
Answers - Pros: See live cells w/out stain, see some internal structures
Cons: Hard for small cells
Pros and Cons of Fluorescence and Confocal Microscopes: - Answers - Pros: High
resolution, 3D, vibrant colors, live cells
Cons: expensive
What is electron microscopy? - Answers - Uses electrons rather than visual light
Advantage of electron microscopy? - Answers - Greater resolution than light microscope
Role of transmission electron microscopy (TEM): - Answers - -See internal structures
-Obtain 3D images
Role of Scanning Electron Microscopes (SEM): - Answers - see surface and external
structures
What is passive transport? - Answers - The movement of materials across the cell
membrane without using cellular energy and with concentration gradient
What is active transport? - Answers - the movement of ions or molecules across a cell
membrane into a region of higher concentration, assisted by enzymes and requiring
energy.
Role of the cell wall? - Answers - Maintain shape and rigidity
Parts of a phospholipid: - Answers - Polar head and non polar tail
Where is peptidoglycan not found? - Answers - Archaea and Eukaryotes
, Where is peptidoglycan found? - Answers - bacteria
What are the parts of peptidoglycan? - Answers - - N-acetylglucosamine
- N-Acetylmuramic acid
-Amino acids
-peptide cross links
Length of lipoteichoic acid: - Answers - Spans entire membrane of peptidoglycan layer
Where are lipoteichoic acids found? - Answers - gram positive cell wall
Length of teichoic acid : - Answers - Doesn't span entire peptidoglycan layer
Where are teichoic acids found? - Answers - gram positive cell walls
Describe the Gram + cell wall: - Answers - Cytoplasmic membrane surrounded by thick
peptidoglycan layer
Where are lipolysaccharides found? - Answers - outer membrane of gram negative cells
What makes up lipolysaccharides from external to internal - Answers - - O-specific
polysaccharide
- Core polysaccharide
Lipid A
What connects the outer membrane of the gram negative cell wall to the peptidoglycan
layer? - Answers - Braun lipoprotein
What is the space called in between the two phospholipid bilayers of a gram negative
cell? - Answers - Periplasm
Describe a gram negative cell wall - Answers - On outside a layer of
lipopolysaccharides -> phospholipid bilayers -> Periplasm space containing thin
peptidoglycan layer -> inner cell membrane
Role of bacterial slime layer? - Answers - - assist in attachment to surfaces
- Contribute to infectivity
- prevent dehydration
What is the role of flagella and fimbriae? - Answers - Mediate attachment
Why are slime layers, flagella, and fimbriae often missing in a lab environment? -
Answers - They aren't required by the microbes and therefore energy isn't wasted
role of cell inclusions - Answers - Energy reserve used
What are the 4 traits of a microbe? - Answers - -Too small to be seen by human eye
-Grow and reproduce in nature
-Active metabolism
-Respond to stimuli
Diameter of a typical microbe? - Answers - 0.2 micrometers (μm) in diameter
Who was the first person to observe single-celled microbes? - Answers - Antonie van
Leeuwenhoek
Where do microbes come from? - Answers - they have parents
who disproved theory of spontaneous generation? - Answers - Louis Pasteur
Louis Pasteur contribution to microbiology? - Answers - disproved spontaneous
generation
Who proved the link between microbes and infectious disease? - Answers - Robert
Koch
Robert Koch's contribution to microbiology? - Answers - Link between microbes and
infectious disease.
What are the two primary types of cells? - Answers - Prokaryotic and Eukaryotic
Is bacteria prokaryotic or eukaryotic? - Answers - Prokaryotic
Is archaea prokaryotic or eukaryotic? - Answers - Prokaryotic
Primary purpose of light microscope? - Answers - Improve contrast and resolution
What is contrast? - Answers - the difference in brightness between the light and dark
areas of an image
What is resolution of an image? - Answers - Ability to distinguish between two objects.
5 types of light microscopy? - Answers - -Bright Field
-Phase contrast
-Differential Interference Contrast
-Dark-field
,-Fluorescence
Color of Gram + cells after gram stain? - Answers - Purple
Color of gram - cells after gram stain - Answers - Red/pink
What is confocal scanning laser microscopy? - Answers - A computerized fluorescent
microscope that uses a laser source to create a 3D image
Pros and Cons of Bright-field microscopy: - Answers - Pros: Simple and affordable
Cons: need staining and difficult to see small/colorless cells
Pros and Cons of dark field microscopy: - Answers - Pros: Highly sensitive for small
cells/structures
Cons: poor resolution and prone to artifacts
Pros and Cons of Phase contrast microscopy and differential interference microscopy: -
Answers - Pros: See live cells w/out stain, see some internal structures
Cons: Hard for small cells
Pros and Cons of Fluorescence and Confocal Microscopes: - Answers - Pros: High
resolution, 3D, vibrant colors, live cells
Cons: expensive
What is electron microscopy? - Answers - Uses electrons rather than visual light
Advantage of electron microscopy? - Answers - Greater resolution than light microscope
Role of transmission electron microscopy (TEM): - Answers - -See internal structures
-Obtain 3D images
Role of Scanning Electron Microscopes (SEM): - Answers - see surface and external
structures
What is passive transport? - Answers - The movement of materials across the cell
membrane without using cellular energy and with concentration gradient
What is active transport? - Answers - the movement of ions or molecules across a cell
membrane into a region of higher concentration, assisted by enzymes and requiring
energy.
Role of the cell wall? - Answers - Maintain shape and rigidity
Parts of a phospholipid: - Answers - Polar head and non polar tail
Where is peptidoglycan not found? - Answers - Archaea and Eukaryotes
, Where is peptidoglycan found? - Answers - bacteria
What are the parts of peptidoglycan? - Answers - - N-acetylglucosamine
- N-Acetylmuramic acid
-Amino acids
-peptide cross links
Length of lipoteichoic acid: - Answers - Spans entire membrane of peptidoglycan layer
Where are lipoteichoic acids found? - Answers - gram positive cell wall
Length of teichoic acid : - Answers - Doesn't span entire peptidoglycan layer
Where are teichoic acids found? - Answers - gram positive cell walls
Describe the Gram + cell wall: - Answers - Cytoplasmic membrane surrounded by thick
peptidoglycan layer
Where are lipolysaccharides found? - Answers - outer membrane of gram negative cells
What makes up lipolysaccharides from external to internal - Answers - - O-specific
polysaccharide
- Core polysaccharide
Lipid A
What connects the outer membrane of the gram negative cell wall to the peptidoglycan
layer? - Answers - Braun lipoprotein
What is the space called in between the two phospholipid bilayers of a gram negative
cell? - Answers - Periplasm
Describe a gram negative cell wall - Answers - On outside a layer of
lipopolysaccharides -> phospholipid bilayers -> Periplasm space containing thin
peptidoglycan layer -> inner cell membrane
Role of bacterial slime layer? - Answers - - assist in attachment to surfaces
- Contribute to infectivity
- prevent dehydration
What is the role of flagella and fimbriae? - Answers - Mediate attachment
Why are slime layers, flagella, and fimbriae often missing in a lab environment? -
Answers - They aren't required by the microbes and therefore energy isn't wasted
role of cell inclusions - Answers - Energy reserve used
