,CONTENT
Chapter 1 Microbiology—The Science
Chapter 2 Viewing the Microbial World
Chapter 3 Cell Structure and Taxonomy
Chapter 4 Acellular and Prokaryotic Microbes
Chapter 5 Eukaryotic Microbes
Chapter 6 The Biochemical Basis of Life
Chapter 7 Microbial Physiology and Genetics
Chapter 8 Controlling Microbial Growth In Vitro
Chapter 9 Inhibiting the Growth of Pathogens In Vivo using Antimicrobial Agents
Chapter 10 Microbial Ecology and Microbial Biotechnology
Chapter 11 Epidemiology and Public Health
Chapter 12 Health Care Epidemiology and Infection Prevention and Control
Chapter 13 Diagnosing Infectious Diseases
Chapter 14 Pathogenesis of Infectious Diseases
Chapter 15 Nonspecific Host Defense Mechanisms
Chapter 16 Specific Host Defense Mechanisms: An Introduction to Immunology
Chapter 17 Overview of Human Infectious Diseases
Chapter 18 Viral Infections of Humans
Chapter 19 Bacterial Infections of Humans
Chapter 20 Fungal Infections of Humans
Chapter 21 Parasitic Infections of
Humans
,Chapter 1 : Microbiology: The Science
Aligned with Chapter 1 — scope, historical foundations (Pasteur, Koch, Lister),
microbes in health/disease/environment/biotech.
1. Which statement most accurately captures the modern, comprehensive scope
of microbiology as a scientific discipline?
A. The study of bacteria and their role in infectious disease.
B. The study of microscopic organisms and acellular agents (bacteria,
archaea, fungi, protozoa, viruses, prions), their structure, physiology,
genetics, ecology, evolution, and applications in health, industry and the
environment.
C. The medical subspecialty concerned only with pathogens that cause
human disease.
D. The study of algae and fungi for food production.
Answer: B
Rationale: Modern microbiology is not limited to bacteria or human pathogens. It
encompasses cellular microbes (bacteria, archaea, fungi, protozoa), acellular agents
(viruses, viroids, prions), and spans basic biology (structure, metabolism, genetics),
ecology (microbial communities, biogeochemical cycles), evolution, and applied
fields (clinical microbiology, biotechnology, industrial microbiology,
bioremediation). Choice B reflects this full breadth; A and C are too narrow, D is a
subset.
Key words: microorganisms, acellular agents, ecology, genetics, biotechnology,
clinical microbiology
2. Louis Pasteur’s “swan-neck flask” experiment is frequently cited in the
history of microbiology. What was the critical feature of his design that
falsified spontaneous generation?
, A. Use of a filter to remove microbes from air before exposure.
B. Boiling the broth and then sealing it hermetically so air could not re-
enter. C. Allowing air contact while preventing particulate (microbial)
entry by a curved (swan-neck) tube so sterile broth remained sterile until
the flask was tilted.
D. Adding antiseptic phenol to broth to prevent growth.
Answer: C
Rationale: Pasteur boiled (sterilized) nutrient broth and used a swan-neck flask
that allowed air to enter but trapped airborne particulates in the curve; the broth
remained sterile until the flask was tipped so trapped particles reached the broth.
This showed that living germs came from other microorganisms, not spontaneous
generation. A filter experiment is similar but Pasteur’s signature demonstration was
the swan-neck design. D refers to Lister’s antiseptic work, not Pasteur’s
experiment.
Key words: Pasteur, swan-neck flask, spontaneous generation, sterilization,
airborne particulates
3. Which of the following best describes a widespread limitation of Koch’s
original postulates when applied to modern infectious diseases? A. They
cannot account for asymptomatic carriers and latent infections.
B. They assume the agent can be cultured in artificial media, which
is not true for all pathogens (e.g., many viruses, obligate intracellular
bacteria, some protozoa).
C. They struggle with polymicrobial diseases and with pathogens
whose disease expression depends on host factors or microbiome
context. D. All of the above.
Answer: D
Rationale: Koch’s postulates were foundational but assume one organism → one
disease and that the organism can be isolated and cultured. Many modern
pathogens violate these assumptions: viruses require host cells; some agents cannot
be cultured; carriers may harbor pathogens without disease; polymicrobial
syndromes and diseases reliant on host susceptibility or microbiome dysbiosis are
not well explained by strict postulates. Thus all listed limitations apply.
,Key words: Koch’s postulates, culture, asymptomatic carriers, polymicrobial, host
susceptibility
4. Joseph Lister pioneered antiseptic surgical practice in the 19th century.
Which agent did he introduce to treat surgical wounds and instruments,
demonstrating reduced postoperative infection rates?
A. Carbolic acid (phenol)
B. Ethanol 70%
C. Iodophors
D. Mercury chloride (corrosive sublimate)
Answer: A
Rationale: Lister introduced phenol (carbolic acid) as an antiseptic to reduce
surgical infection, building on germ theory. His work promoted the concept of
disinfecting instruments and wounds; later practices evolved toward aseptic (sterile
technique) approaches and safer antiseptics, but phenol was Lister’s hallmark.
Ethanol and iodophors are antiseptics used later; mercury salts were older but
toxic.
Key words: Lister, antiseptic, phenol, surgical infection, asepsis
5. The resident gut microbiota confers “colonization resistance” against
incoming pathogens. Which mechanism most directly mediates this
protective effect?
A. Induction of systemic IgG antibodies that neutralize pathogens in the gut
lumen.
B. Competition for nutrients and niche space combined with production of
inhibitory metabolites and bacteriocins that limit pathogen establishment.
C. Increasing hydrochloric acid secretion in the stomach through microbial
signaling.
D. Direct phagocytosis of pathogens by commensal bacteria.
Answer: B
, Rationale: Colonization resistance is principally mediated by competition for
adhesion sites and nutrients, production of inhibitory compounds (short-chain fatty
acids, bacteriocins), and modulation of the mucosal immune response. Systemic
IgG is less relevant for lumenal competition; commensal bacteria do not
phagocytose pathogens. Microbiota effects on stomach acid are indirect and not the
main mechanism.
Key words: colonization resistance, competition, bacteriocins, short-chain fatty
acids, microbiota
6. The commercial production of recombinant human insulin historically used
which microbial biotechnology approach?
A. Direct chemical synthesis of insulin peptide chains followed by chemical
ligation.
B. Extraction and purification of insulin from porcine or bovine pancreas.
C. Cloning the human insulin gene into E. coli expression vectors to produce
human insulin polypeptides for purification.
D. Using filamentous fungi that naturally secrete insulin analogs.
Answer: C
Rationale: Modern human recombinant insulin was produced by inserting human
insulin genes into plasmids in E. coli, expressing the polypeptides, and purifying
the product — a landmark application of recombinant DNA technology. Chemical
synthesis and animal extraction were used historically but have disadvantages;
filamentous fungi do not naturally produce insulin.
Key words: recombinant DNA, E. coli, insulin, expression vector, biotechnology
7. Viruses are routinely described as “acellular.” Which property best justifies
that classification?
A. Presence of a protein capsid surrounding a nucleic acid.
B. Ability to infect prokaryotic and eukaryotic cells.
C. Lack of independent metabolic activity and inability to replicate without
host cellular machinery.
D. Small size relative to bacteria.
Chapter 1 Microbiology—The Science
Chapter 2 Viewing the Microbial World
Chapter 3 Cell Structure and Taxonomy
Chapter 4 Acellular and Prokaryotic Microbes
Chapter 5 Eukaryotic Microbes
Chapter 6 The Biochemical Basis of Life
Chapter 7 Microbial Physiology and Genetics
Chapter 8 Controlling Microbial Growth In Vitro
Chapter 9 Inhibiting the Growth of Pathogens In Vivo using Antimicrobial Agents
Chapter 10 Microbial Ecology and Microbial Biotechnology
Chapter 11 Epidemiology and Public Health
Chapter 12 Health Care Epidemiology and Infection Prevention and Control
Chapter 13 Diagnosing Infectious Diseases
Chapter 14 Pathogenesis of Infectious Diseases
Chapter 15 Nonspecific Host Defense Mechanisms
Chapter 16 Specific Host Defense Mechanisms: An Introduction to Immunology
Chapter 17 Overview of Human Infectious Diseases
Chapter 18 Viral Infections of Humans
Chapter 19 Bacterial Infections of Humans
Chapter 20 Fungal Infections of Humans
Chapter 21 Parasitic Infections of
Humans
,Chapter 1 : Microbiology: The Science
Aligned with Chapter 1 — scope, historical foundations (Pasteur, Koch, Lister),
microbes in health/disease/environment/biotech.
1. Which statement most accurately captures the modern, comprehensive scope
of microbiology as a scientific discipline?
A. The study of bacteria and their role in infectious disease.
B. The study of microscopic organisms and acellular agents (bacteria,
archaea, fungi, protozoa, viruses, prions), their structure, physiology,
genetics, ecology, evolution, and applications in health, industry and the
environment.
C. The medical subspecialty concerned only with pathogens that cause
human disease.
D. The study of algae and fungi for food production.
Answer: B
Rationale: Modern microbiology is not limited to bacteria or human pathogens. It
encompasses cellular microbes (bacteria, archaea, fungi, protozoa), acellular agents
(viruses, viroids, prions), and spans basic biology (structure, metabolism, genetics),
ecology (microbial communities, biogeochemical cycles), evolution, and applied
fields (clinical microbiology, biotechnology, industrial microbiology,
bioremediation). Choice B reflects this full breadth; A and C are too narrow, D is a
subset.
Key words: microorganisms, acellular agents, ecology, genetics, biotechnology,
clinical microbiology
2. Louis Pasteur’s “swan-neck flask” experiment is frequently cited in the
history of microbiology. What was the critical feature of his design that
falsified spontaneous generation?
, A. Use of a filter to remove microbes from air before exposure.
B. Boiling the broth and then sealing it hermetically so air could not re-
enter. C. Allowing air contact while preventing particulate (microbial)
entry by a curved (swan-neck) tube so sterile broth remained sterile until
the flask was tilted.
D. Adding antiseptic phenol to broth to prevent growth.
Answer: C
Rationale: Pasteur boiled (sterilized) nutrient broth and used a swan-neck flask
that allowed air to enter but trapped airborne particulates in the curve; the broth
remained sterile until the flask was tipped so trapped particles reached the broth.
This showed that living germs came from other microorganisms, not spontaneous
generation. A filter experiment is similar but Pasteur’s signature demonstration was
the swan-neck design. D refers to Lister’s antiseptic work, not Pasteur’s
experiment.
Key words: Pasteur, swan-neck flask, spontaneous generation, sterilization,
airborne particulates
3. Which of the following best describes a widespread limitation of Koch’s
original postulates when applied to modern infectious diseases? A. They
cannot account for asymptomatic carriers and latent infections.
B. They assume the agent can be cultured in artificial media, which
is not true for all pathogens (e.g., many viruses, obligate intracellular
bacteria, some protozoa).
C. They struggle with polymicrobial diseases and with pathogens
whose disease expression depends on host factors or microbiome
context. D. All of the above.
Answer: D
Rationale: Koch’s postulates were foundational but assume one organism → one
disease and that the organism can be isolated and cultured. Many modern
pathogens violate these assumptions: viruses require host cells; some agents cannot
be cultured; carriers may harbor pathogens without disease; polymicrobial
syndromes and diseases reliant on host susceptibility or microbiome dysbiosis are
not well explained by strict postulates. Thus all listed limitations apply.
,Key words: Koch’s postulates, culture, asymptomatic carriers, polymicrobial, host
susceptibility
4. Joseph Lister pioneered antiseptic surgical practice in the 19th century.
Which agent did he introduce to treat surgical wounds and instruments,
demonstrating reduced postoperative infection rates?
A. Carbolic acid (phenol)
B. Ethanol 70%
C. Iodophors
D. Mercury chloride (corrosive sublimate)
Answer: A
Rationale: Lister introduced phenol (carbolic acid) as an antiseptic to reduce
surgical infection, building on germ theory. His work promoted the concept of
disinfecting instruments and wounds; later practices evolved toward aseptic (sterile
technique) approaches and safer antiseptics, but phenol was Lister’s hallmark.
Ethanol and iodophors are antiseptics used later; mercury salts were older but
toxic.
Key words: Lister, antiseptic, phenol, surgical infection, asepsis
5. The resident gut microbiota confers “colonization resistance” against
incoming pathogens. Which mechanism most directly mediates this
protective effect?
A. Induction of systemic IgG antibodies that neutralize pathogens in the gut
lumen.
B. Competition for nutrients and niche space combined with production of
inhibitory metabolites and bacteriocins that limit pathogen establishment.
C. Increasing hydrochloric acid secretion in the stomach through microbial
signaling.
D. Direct phagocytosis of pathogens by commensal bacteria.
Answer: B
, Rationale: Colonization resistance is principally mediated by competition for
adhesion sites and nutrients, production of inhibitory compounds (short-chain fatty
acids, bacteriocins), and modulation of the mucosal immune response. Systemic
IgG is less relevant for lumenal competition; commensal bacteria do not
phagocytose pathogens. Microbiota effects on stomach acid are indirect and not the
main mechanism.
Key words: colonization resistance, competition, bacteriocins, short-chain fatty
acids, microbiota
6. The commercial production of recombinant human insulin historically used
which microbial biotechnology approach?
A. Direct chemical synthesis of insulin peptide chains followed by chemical
ligation.
B. Extraction and purification of insulin from porcine or bovine pancreas.
C. Cloning the human insulin gene into E. coli expression vectors to produce
human insulin polypeptides for purification.
D. Using filamentous fungi that naturally secrete insulin analogs.
Answer: C
Rationale: Modern human recombinant insulin was produced by inserting human
insulin genes into plasmids in E. coli, expressing the polypeptides, and purifying
the product — a landmark application of recombinant DNA technology. Chemical
synthesis and animal extraction were used historically but have disadvantages;
filamentous fungi do not naturally produce insulin.
Key words: recombinant DNA, E. coli, insulin, expression vector, biotechnology
7. Viruses are routinely described as “acellular.” Which property best justifies
that classification?
A. Presence of a protein capsid surrounding a nucleic acid.
B. Ability to infect prokaryotic and eukaryotic cells.
C. Lack of independent metabolic activity and inability to replicate without
host cellular machinery.
D. Small size relative to bacteria.
