WGU D311
Microbiology
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,1. Which statement describes prokaryotic cells?
a) Prokaryotic cells are found in coccus form in both pairs and clusters.
b) Prokaryotic cells have multiple rod-shaped chromosomes.
c) Prokaryotic cells are found in chains of rods but not single rods.
d) Prokaryotic cells have a nucleus surrounded by a complex nuclear membrane.
Correct Answer: A
Explanation:
This is correct because prokaryotic cells can form cocus in both pairs and clusters
2. Which statement describes eukaryotic cells?
a) The exoskeletons of eukaryotic cells maintain and support the cells' shapes.
b) The nuclei of eukaryotic cells are surrounded by complex nuclear membranes.
c) The genomes of eukaryotic cells are usually packaged in single circular chromosomes.
d) The organelles of eukaryotic cells are held in place by semipermeable exoskeletons.
Correct Answer: B
3. Which statement describes eukaryotic flagella?
a) Eukaryotic flagella can cover the entire surface of a cell.
b) Eukaryotic flagella are rotating structures.
c) Eukaryotic flagella have twelve pairs of microtubules.
d) Eukaryotic flagella are flexible, whip-like structures.
Correct Answer: D
4. Which statement describes the endomembrane system?
a) It is attached to the smooth endoplasmic reticulum and makes proteins for insertion
into the cell membrane.
b) It includes the Golgi apparatus, lysosomes, and vesicles.
c) It is a system that uses diffusion to transport materials inside of the cell.
, d) It lacks membrane-bound organelles.
Correct Answer: B
5. Which statement accurately describes similarities between protozoa and fungi?
a) Both perform chemosynthesis.
b) Both can be harmful or harmless depending on the context.
c) Both are made of long filaments that form visible colonies.
d) Both move with help from cilia and flagella.
Correct Answer: B
6. Why are algae considered photosynthetic organisms?
a) Algae cell walls are constructed with a material called peptidoglycan.
b) Algae contain substances that can be converted into biofuels.
c) Algae produce chemical energy from the sun's light energy.
d) Algae create waste products that other organisms can use to make energy.
Correct Answer: C
7. Why are plasmids important to the survival of organisms?
a) Plasmids exclusively contain the genes responsible for cellular replication in bacteria.
b) Plasmids can store excess nutrients in the cytoplasm of the cell.
c) Plasmids protect the bacterial genome in a dormant state during unfavorable
environmental conditions.
d) Plasmids carry genetic material, apart from the genome, that can benefit the
organism.
Correct Answer: D
Explanation:
Plasmids often carry genes that can offer beneficial traits such as antibiotic resistance
8. Which statement describes bacteria?
a) Some bacteria are eukaryotes.
, b) Some bacteria have cell walls composed of mycolic acid.
c) Some bacteria are motile by cilia.
d) Some bacteria have cell walls composed of chitin.
Correct Answer: B
Explanation:
Mycolic acid can be found in the cell walls of acid-fast bacteria
9. Why are prokaryotes vital to life?
Correct Answer: Prokaryotes are vital to life because they are able to recycle elements
like carbon and nutrients. Organisms like animals need organic carbon in order to
grow but, unlike prokaryotes, they are unable to use inorganic carbon sources like
CO2. The enzyme nitrogenase is only found in prokaryotes
10. Which aspect of nutrient cycling is performed only by prokaryotes?
a) Respiration process
b) Carbon fixation
c) Nitrate assimilation
d) Nitrogen fixation
Correct Answer: D
Explanation:
The enzyme nitrogenase is only found in prokaryotes; it is vital to life and the process
of nitrogen fixation
11. How does microbial bioremediation benefit the environment?
a) By helping to minimize the growth of pathogens in different parts of the body
b) By helping to metabolize and remove pollutants in the atmosphere
c) By producing complex organic pharmaceutical compounds used in antibiotics,
vaccines, and vitamins
d) By producing gases, such as carbon dioxide, which are used to make biofuels
, Correct Answer: B
Explanation:
This is the correct answer because the definition of bioremediation is the process of
bacteria using a toxic structure to grow which leads to it being removed from the
environment. Occurs often by breaking it down into its nontoxic components
12. What describes the relationship of pathogens to virulence?
a) Highly virulent pathogens almost always lead to a disease state when introduced to
the body.
b) Pathogens that cause an infection cannot also be virulent.
c) Highly virulent pathogens are highly susceptible to the human immune system.
d) Less virulent pathogens are less likely to lead to an infection.
Correct Answer: A
13. What is the key difference between a primary pathogen and an opportunistic
pathogen?
a) Primary pathogens can be fought off by the body's immune defense system, whereas
opportunistic pathogens require synthetic interventions.
b) Primary pathogens can infect certain people, whereas opportunistic pathogens can
infect anyone.
c) Primary pathogens can infect anyone, whereas opportunistic pathogens can cause
disease if the host is immunocompromised.
d) Primary pathogens are part of the human microbiome, whereas opportunistic
pathogens are transmitted from another host.
Correct Answer: C
14. How can disease expression be described?
a) Pathogens with high virulence tend to cause symptoms that include low-grade fevers
or headaches.
b) The infectious dose that is needed to cause illness is consistent from person to
person.
, c) Virulent microorganisms result in the same form of disease in the host regardless of
the route of transmission.
d) Signs and symptoms associated with illness can be a result of many things, including
an immune response
Correct Answer: D
15. What is the correct understanding of the median infectious dose?
a) It is the number of pathogenic cells required to kill 50% of infected animals.
b) It is the number of pathogenic cells required to cause active infection in 50% of
inoculated animals.
c) It is the amount of toxin required to see an immune response to infection in 50% of
people.
d) It is the amount of toxin required to infect 50% of the human population.
Correct Answer: B
16. Which structure aids in the evasion of phagocytosis by preventing immune cells
from adhering to pathogens?
a) Pili
b) Fimbriae
c) Peptidoglycan
d) Capsule
Correct Answer: D
17. Which group contains a pathogen that adheres to host cells by using a large
adhesive disc?
a) Viruses
b) Protozoans
c) Fungi
d) Bacteria
Correct Answer: B
,18. Which phenomenon is found only in viruses?
a) Antigenic drift
b) Antigenic shift
c) Mycotoxin production
d) Capsule formation
Correct Answer: B
Explanation:
This is a major change of surface antigens that can occur when multiple viruses invade
a single cell causing their genomes to mix and resort
19. Which structure is used by certain bacteria to adhere to host tissues?
a) Mycolic acid
b) Glycoprotein gp120
c) Type 1 fimbrial adhesin
d) M protein
Correct Answer: C
20. Which virulence factor aids in the adherence of bacterial pathogens to a host?
a) Endotoxin
b) Capsule
c) O antigen
d) Pili
Correct Answer: D
Explanation:
These are long protein appendages that help in attachment to surfaces
21. Which situation is an indirect result of endotoxin release?
a) Phagocytes are recruited to the area.
b) Inflammation and fever are initiated
c) Host cells are lysed.
, d) Antiviral proteins are produced.
Correct Answer: B
Explanation:
The release of endotoxins from gram negative bacteria triggers the immune system's
inflammatory response. This can lead to fever
22. Which characteristic is true of exotoxins?
a) Exotoxins are produced by only gram-negative bacteria.
b) Exotoxins are stable at high temperatures.
c) Exotoxins are produced by only gram-positive bacteria.
d) Exotoxins can cause cytokine storms.
Correct Answer: D
Explanation:
Exotoxins can trigger immune cells to release cytokines leading to a cytokine storm
23. Which statement describes biofilms?
a) Biofilms contain random collections of microorganisms.
b) Biofilms are always pathogenic to the host.
c) Biofilms form on fomites.
d) Biofilms are highly structured communities.
Correct Answer: D
24. Which step in biofilm formation comes immediately after planktonic cells attach to
a surface?
a) Planktonic cells become sessile.
b) Appendages and the extracellular polymeric substance interact.
c) Sessile cells become planktonic.
d) Planktonic cells colonize new areas.
, Correct Answer: A
Explanation:
Planktonic cells become sessile as soon as they attach to a surface
25. Which biofilms are produced by mutualistic microbes and are beneficial to a human
host?
a) Plaque biofilms that form on teeth
b) Biofilms that line the intestinal mucosa
c) Staphylococcus biofilms that form on urinary catheters
d) Pseudomonas aeruginosa biofilms that form in the airway
Correct Answer: B
Explanation:
This is mutualistic as the microbes are able ward off infections by pathogens and
continue living in their biofilm community. Both the pathogen and host benefit from
the relationship
26. Why would bacteria living in a biofilm slow down their metabolism?
Correct Answer: To survive the low-nutrient environment deep in the biofilm
structure Bacteria need to slow down their metabolism in order to survive in deep
biofilms where nutrients are limited. This is done in order to increase the level of
resistance
27. Which type of microscopy allows the visualization of internal cellular structures in
specially fixed microbial specimens?
a) Differential interference contrast microscopy
b) Fluorescence microscopy
c) Brightfield microscopy
d) Electron microscopy
Microbiology
OA EXAM PREP
Actual Questions with Verified Answers
Pass the Exam with Confidence
What You Will Get:
➢226 OA Exam Questions w/ Answers
➢ OA Definitions,
➢ Concept Reviews
➢ Study Guide
➢ Expert Rationales included.
Take and pass the OA :)
, Preview Pages Below
Get the Complete PDF After Purchase
STUDENT PREVIEW
If you require further clarification
or in need of any study resources,
feel free to Message me.
Preview the selected pages below before purchase.
,1. Which statement describes prokaryotic cells?
a) Prokaryotic cells are found in coccus form in both pairs and clusters.
b) Prokaryotic cells have multiple rod-shaped chromosomes.
c) Prokaryotic cells are found in chains of rods but not single rods.
d) Prokaryotic cells have a nucleus surrounded by a complex nuclear membrane.
Correct Answer: A
Explanation:
This is correct because prokaryotic cells can form cocus in both pairs and clusters
2. Which statement describes eukaryotic cells?
a) The exoskeletons of eukaryotic cells maintain and support the cells' shapes.
b) The nuclei of eukaryotic cells are surrounded by complex nuclear membranes.
c) The genomes of eukaryotic cells are usually packaged in single circular chromosomes.
d) The organelles of eukaryotic cells are held in place by semipermeable exoskeletons.
Correct Answer: B
3. Which statement describes eukaryotic flagella?
a) Eukaryotic flagella can cover the entire surface of a cell.
b) Eukaryotic flagella are rotating structures.
c) Eukaryotic flagella have twelve pairs of microtubules.
d) Eukaryotic flagella are flexible, whip-like structures.
Correct Answer: D
4. Which statement describes the endomembrane system?
a) It is attached to the smooth endoplasmic reticulum and makes proteins for insertion
into the cell membrane.
b) It includes the Golgi apparatus, lysosomes, and vesicles.
c) It is a system that uses diffusion to transport materials inside of the cell.
, d) It lacks membrane-bound organelles.
Correct Answer: B
5. Which statement accurately describes similarities between protozoa and fungi?
a) Both perform chemosynthesis.
b) Both can be harmful or harmless depending on the context.
c) Both are made of long filaments that form visible colonies.
d) Both move with help from cilia and flagella.
Correct Answer: B
6. Why are algae considered photosynthetic organisms?
a) Algae cell walls are constructed with a material called peptidoglycan.
b) Algae contain substances that can be converted into biofuels.
c) Algae produce chemical energy from the sun's light energy.
d) Algae create waste products that other organisms can use to make energy.
Correct Answer: C
7. Why are plasmids important to the survival of organisms?
a) Plasmids exclusively contain the genes responsible for cellular replication in bacteria.
b) Plasmids can store excess nutrients in the cytoplasm of the cell.
c) Plasmids protect the bacterial genome in a dormant state during unfavorable
environmental conditions.
d) Plasmids carry genetic material, apart from the genome, that can benefit the
organism.
Correct Answer: D
Explanation:
Plasmids often carry genes that can offer beneficial traits such as antibiotic resistance
8. Which statement describes bacteria?
a) Some bacteria are eukaryotes.
, b) Some bacteria have cell walls composed of mycolic acid.
c) Some bacteria are motile by cilia.
d) Some bacteria have cell walls composed of chitin.
Correct Answer: B
Explanation:
Mycolic acid can be found in the cell walls of acid-fast bacteria
9. Why are prokaryotes vital to life?
Correct Answer: Prokaryotes are vital to life because they are able to recycle elements
like carbon and nutrients. Organisms like animals need organic carbon in order to
grow but, unlike prokaryotes, they are unable to use inorganic carbon sources like
CO2. The enzyme nitrogenase is only found in prokaryotes
10. Which aspect of nutrient cycling is performed only by prokaryotes?
a) Respiration process
b) Carbon fixation
c) Nitrate assimilation
d) Nitrogen fixation
Correct Answer: D
Explanation:
The enzyme nitrogenase is only found in prokaryotes; it is vital to life and the process
of nitrogen fixation
11. How does microbial bioremediation benefit the environment?
a) By helping to minimize the growth of pathogens in different parts of the body
b) By helping to metabolize and remove pollutants in the atmosphere
c) By producing complex organic pharmaceutical compounds used in antibiotics,
vaccines, and vitamins
d) By producing gases, such as carbon dioxide, which are used to make biofuels
, Correct Answer: B
Explanation:
This is the correct answer because the definition of bioremediation is the process of
bacteria using a toxic structure to grow which leads to it being removed from the
environment. Occurs often by breaking it down into its nontoxic components
12. What describes the relationship of pathogens to virulence?
a) Highly virulent pathogens almost always lead to a disease state when introduced to
the body.
b) Pathogens that cause an infection cannot also be virulent.
c) Highly virulent pathogens are highly susceptible to the human immune system.
d) Less virulent pathogens are less likely to lead to an infection.
Correct Answer: A
13. What is the key difference between a primary pathogen and an opportunistic
pathogen?
a) Primary pathogens can be fought off by the body's immune defense system, whereas
opportunistic pathogens require synthetic interventions.
b) Primary pathogens can infect certain people, whereas opportunistic pathogens can
infect anyone.
c) Primary pathogens can infect anyone, whereas opportunistic pathogens can cause
disease if the host is immunocompromised.
d) Primary pathogens are part of the human microbiome, whereas opportunistic
pathogens are transmitted from another host.
Correct Answer: C
14. How can disease expression be described?
a) Pathogens with high virulence tend to cause symptoms that include low-grade fevers
or headaches.
b) The infectious dose that is needed to cause illness is consistent from person to
person.
, c) Virulent microorganisms result in the same form of disease in the host regardless of
the route of transmission.
d) Signs and symptoms associated with illness can be a result of many things, including
an immune response
Correct Answer: D
15. What is the correct understanding of the median infectious dose?
a) It is the number of pathogenic cells required to kill 50% of infected animals.
b) It is the number of pathogenic cells required to cause active infection in 50% of
inoculated animals.
c) It is the amount of toxin required to see an immune response to infection in 50% of
people.
d) It is the amount of toxin required to infect 50% of the human population.
Correct Answer: B
16. Which structure aids in the evasion of phagocytosis by preventing immune cells
from adhering to pathogens?
a) Pili
b) Fimbriae
c) Peptidoglycan
d) Capsule
Correct Answer: D
17. Which group contains a pathogen that adheres to host cells by using a large
adhesive disc?
a) Viruses
b) Protozoans
c) Fungi
d) Bacteria
Correct Answer: B
,18. Which phenomenon is found only in viruses?
a) Antigenic drift
b) Antigenic shift
c) Mycotoxin production
d) Capsule formation
Correct Answer: B
Explanation:
This is a major change of surface antigens that can occur when multiple viruses invade
a single cell causing their genomes to mix and resort
19. Which structure is used by certain bacteria to adhere to host tissues?
a) Mycolic acid
b) Glycoprotein gp120
c) Type 1 fimbrial adhesin
d) M protein
Correct Answer: C
20. Which virulence factor aids in the adherence of bacterial pathogens to a host?
a) Endotoxin
b) Capsule
c) O antigen
d) Pili
Correct Answer: D
Explanation:
These are long protein appendages that help in attachment to surfaces
21. Which situation is an indirect result of endotoxin release?
a) Phagocytes are recruited to the area.
b) Inflammation and fever are initiated
c) Host cells are lysed.
, d) Antiviral proteins are produced.
Correct Answer: B
Explanation:
The release of endotoxins from gram negative bacteria triggers the immune system's
inflammatory response. This can lead to fever
22. Which characteristic is true of exotoxins?
a) Exotoxins are produced by only gram-negative bacteria.
b) Exotoxins are stable at high temperatures.
c) Exotoxins are produced by only gram-positive bacteria.
d) Exotoxins can cause cytokine storms.
Correct Answer: D
Explanation:
Exotoxins can trigger immune cells to release cytokines leading to a cytokine storm
23. Which statement describes biofilms?
a) Biofilms contain random collections of microorganisms.
b) Biofilms are always pathogenic to the host.
c) Biofilms form on fomites.
d) Biofilms are highly structured communities.
Correct Answer: D
24. Which step in biofilm formation comes immediately after planktonic cells attach to
a surface?
a) Planktonic cells become sessile.
b) Appendages and the extracellular polymeric substance interact.
c) Sessile cells become planktonic.
d) Planktonic cells colonize new areas.
, Correct Answer: A
Explanation:
Planktonic cells become sessile as soon as they attach to a surface
25. Which biofilms are produced by mutualistic microbes and are beneficial to a human
host?
a) Plaque biofilms that form on teeth
b) Biofilms that line the intestinal mucosa
c) Staphylococcus biofilms that form on urinary catheters
d) Pseudomonas aeruginosa biofilms that form in the airway
Correct Answer: B
Explanation:
This is mutualistic as the microbes are able ward off infections by pathogens and
continue living in their biofilm community. Both the pathogen and host benefit from
the relationship
26. Why would bacteria living in a biofilm slow down their metabolism?
Correct Answer: To survive the low-nutrient environment deep in the biofilm
structure Bacteria need to slow down their metabolism in order to survive in deep
biofilms where nutrients are limited. This is done in order to increase the level of
resistance
27. Which type of microscopy allows the visualization of internal cellular structures in
specially fixed microbial specimens?
a) Differential interference contrast microscopy
b) Fluorescence microscopy
c) Brightfield microscopy
d) Electron microscopy
