UIUC MCB 100 Exam 2 Questions with Correct Answers Latest Update 2025/2026
Who created the 5 kingdom classification? - Answers Robert Whittaker
What kingdom is yeast classified as? - Answers Fungi
What is the universal tree of life based on? - Answers ribosomal 16S rRNA genes
What is the basis for assigning organisms into the three different domains of life (Bacteria,
Archaea, and Eukarya)? - Answers rRNA gene sequences
What's the difference between Streptococcus and Staphylococcus? - Answers strep is chain,
staph is a cluster
What do myxobacteria undergo when in starvation conditions? gram positive or negative? -
Answers they sporulate and form fruiting bodies, stains gram negative
Are actinomycetes gram positive or negative? - Answers spore-forming gram positive bacteria,
often mistaken for fungi
Which of the following is NOT an advantage to life in a microbial biofilm?
A. Decreased diffusion of oxygen that creates a new microniche
B. Enhanced resource trafficking between cells
C. Increased resistance to antibiotics
D. Increased communication between cells
E. Increased predation by amoeba and other Eukaryotic microbes - Answers E
Bacteria Biofilm Formation steps - Answers 1. free-swimming bacteria
2. planktonic stage
3. attachment and aggregation
4. fruiting body
5. endospore stage (optional)
Biofilm formation begins with _______
A. cells maturing and dividing.
B. a slimy polysaccharide matrix being secreted.
C. free-floating cells attaching to a surface.
,D. a bunch of cells clustering together.
E. extracellular polymer substances clumping. - Answers C
What is biofilm matrix composed of? - Answers extracellular polysaccharide coating, not as
strong as capsules
How can biofilm formation be detected? - Answers crystal violet dye staining
Which of the following statements about biofilms is TRUE?A. In biofilms there is often
metabolic cooperation among bacteria.
B. In biofilms, all the bacteria are living, but those that die are released into the medium.
C. In a single-species biofilm, the interior environment is uniform throughout.
D. The environment of the biofilm matrix is not conducive to uptake of colored dyes.
E. Bacteria in biofilms cannot continue to grow at low nutrient concentrations. - Answers A
What are some medical problems that biofilms cause? - Answers - Legionairres disease
- dental caries
- infection of medical devices
- pseudomonas
Where are vibrio species found and why do they often get trapped? - Answers they are found in
marine environments and have long pili/flagella which causes them to get tangled
Biofilms can be found benefiting our bodies _______
A. in the mouth.
B. on contact lenses.
C. on replacement joints.
D. in the lung trachea.
E. in the intestinal tract. - Answers E
What are the three kinds of motility? - Answers flagellar, twitching, gliding
How does vibrio cholerae infect the host? - Answers They have a single polar flagellum that
allows them to move through even viscous liquids
How do spirochetes avoid immune detection? - Answers They have a flagellum inside their
, periplasm
What does counterclockwise rotation indicate about a flagellated bacteria? - Answers aligns the
flagella into a helical bundle causing them to move in a straight line
What does clockwise rotation indicate about a flagellated bacteria? - Answers breaks the bundle
apart, causing bacterium to tumble in place and switch direction
Taxes - Answers ability of bacterium to sense chemicals, followed by directional movement
towards or away from the signal, key role of virulence
What bacteria uses chemotaxis to go deeper into intestinal epithelium? - Answers H. pylori
What make listeria so dangerous? - Answers It is a psychrophile, meaning it can grow in low-
temperature conditions. Can be fatal and cause spontaneous abortion
Why do doctors caution patients who are pregnant to avoid deli meats, cold cuts, and soft
cheeses?
A. The Listeria bacteria can degrade the nutrients in the food no longer providing nutrients for
the fetus.
B. The Listeria bacteria can make these foods taste sour.
C. These foods are used by the Listeria bacteria to make neurotoxins.
D. Fermentation of those foods by Listeria will cause nausea and cramping.
E. The Listeria bacteria can grow in the food when stored in the refrigerator and then infect
those who are immunocompromised. - Answers E
What kind of motility does listeria utilize? - Answers actin-based motility
What is actin-based motility? - Answers cell to cell spread without exposure to antibody immune
system. has to lyse the vacuole in order to move through the cytoplasm
Which of the following statements about Gram-positive Listeria is TRUE?
A. They move rapidly through the body using multiple flagella.
B. They resist most antimicrobial agents due to biofilm formation.
C. They produce pore-forming toxins that lyse and kill eukaryotic cells.
D. They can invade and live within cells to avoid the host's immune system.
E. They form resistant endospores that can withstand harsh chemical environments. - Answers
D
Who created the 5 kingdom classification? - Answers Robert Whittaker
What kingdom is yeast classified as? - Answers Fungi
What is the universal tree of life based on? - Answers ribosomal 16S rRNA genes
What is the basis for assigning organisms into the three different domains of life (Bacteria,
Archaea, and Eukarya)? - Answers rRNA gene sequences
What's the difference between Streptococcus and Staphylococcus? - Answers strep is chain,
staph is a cluster
What do myxobacteria undergo when in starvation conditions? gram positive or negative? -
Answers they sporulate and form fruiting bodies, stains gram negative
Are actinomycetes gram positive or negative? - Answers spore-forming gram positive bacteria,
often mistaken for fungi
Which of the following is NOT an advantage to life in a microbial biofilm?
A. Decreased diffusion of oxygen that creates a new microniche
B. Enhanced resource trafficking between cells
C. Increased resistance to antibiotics
D. Increased communication between cells
E. Increased predation by amoeba and other Eukaryotic microbes - Answers E
Bacteria Biofilm Formation steps - Answers 1. free-swimming bacteria
2. planktonic stage
3. attachment and aggregation
4. fruiting body
5. endospore stage (optional)
Biofilm formation begins with _______
A. cells maturing and dividing.
B. a slimy polysaccharide matrix being secreted.
C. free-floating cells attaching to a surface.
,D. a bunch of cells clustering together.
E. extracellular polymer substances clumping. - Answers C
What is biofilm matrix composed of? - Answers extracellular polysaccharide coating, not as
strong as capsules
How can biofilm formation be detected? - Answers crystal violet dye staining
Which of the following statements about biofilms is TRUE?A. In biofilms there is often
metabolic cooperation among bacteria.
B. In biofilms, all the bacteria are living, but those that die are released into the medium.
C. In a single-species biofilm, the interior environment is uniform throughout.
D. The environment of the biofilm matrix is not conducive to uptake of colored dyes.
E. Bacteria in biofilms cannot continue to grow at low nutrient concentrations. - Answers A
What are some medical problems that biofilms cause? - Answers - Legionairres disease
- dental caries
- infection of medical devices
- pseudomonas
Where are vibrio species found and why do they often get trapped? - Answers they are found in
marine environments and have long pili/flagella which causes them to get tangled
Biofilms can be found benefiting our bodies _______
A. in the mouth.
B. on contact lenses.
C. on replacement joints.
D. in the lung trachea.
E. in the intestinal tract. - Answers E
What are the three kinds of motility? - Answers flagellar, twitching, gliding
How does vibrio cholerae infect the host? - Answers They have a single polar flagellum that
allows them to move through even viscous liquids
How do spirochetes avoid immune detection? - Answers They have a flagellum inside their
, periplasm
What does counterclockwise rotation indicate about a flagellated bacteria? - Answers aligns the
flagella into a helical bundle causing them to move in a straight line
What does clockwise rotation indicate about a flagellated bacteria? - Answers breaks the bundle
apart, causing bacterium to tumble in place and switch direction
Taxes - Answers ability of bacterium to sense chemicals, followed by directional movement
towards or away from the signal, key role of virulence
What bacteria uses chemotaxis to go deeper into intestinal epithelium? - Answers H. pylori
What make listeria so dangerous? - Answers It is a psychrophile, meaning it can grow in low-
temperature conditions. Can be fatal and cause spontaneous abortion
Why do doctors caution patients who are pregnant to avoid deli meats, cold cuts, and soft
cheeses?
A. The Listeria bacteria can degrade the nutrients in the food no longer providing nutrients for
the fetus.
B. The Listeria bacteria can make these foods taste sour.
C. These foods are used by the Listeria bacteria to make neurotoxins.
D. Fermentation of those foods by Listeria will cause nausea and cramping.
E. The Listeria bacteria can grow in the food when stored in the refrigerator and then infect
those who are immunocompromised. - Answers E
What kind of motility does listeria utilize? - Answers actin-based motility
What is actin-based motility? - Answers cell to cell spread without exposure to antibody immune
system. has to lyse the vacuole in order to move through the cytoplasm
Which of the following statements about Gram-positive Listeria is TRUE?
A. They move rapidly through the body using multiple flagella.
B. They resist most antimicrobial agents due to biofilm formation.
C. They produce pore-forming toxins that lyse and kill eukaryotic cells.
D. They can invade and live within cells to avoid the host's immune system.
E. They form resistant endospores that can withstand harsh chemical environments. - Answers
D
