Test Bank for Microbiology The Human
Experience 3rd Edition by John Foster,
Zarrintaj Aliabadi
Exam
Chapter 1: Microbes Shape Our History (Q 1-25)
1. Which of the following is a beneficial role of microorganisms in the human body?
A) Production of vitamin K in the gut
B) Destruction of red blood cells
C) Formation of dental plaque
D) Causing urinary tract infections
Answer: A
Rationale: Gut bacteria synthesize vitamin K, which is essential for blood clotting. The other options are
harmful or pathological .
2. The three domains of life according to the Woese system are:
A) Prokaryota, Eukaryota, Fungi
B) Bacteria, Archaea, Eukarya
C) Plantae, Animalia, Protista
D) Monera, Protista, Fungi
Answer: B
Rationale: The three-domain system is based on ribosomal RNA analysis and includes Bacteria, Archaea,
and Eukarya .
3. Louis Pasteur’s swan-neck flask experiment demonstrated that:
A) Spontaneous generation is possible under certain conditions
B) Microbial life arises from pre-existing microbes (biogenesis)
C) Heat sterilization destroys all microbial life
D) Microbes are present in the air
Answer: B
Rationale: The experiment showed that broth remained sterile unless exposed to dust, disproving
spontaneous generation .
4. The human microbiome refers to:
A) The collection of all viruses in a human body
B) The total genetic content of a human
C) The aggregate of all microorganisms living in and on the human body
D) The set of all bacterial toxins
, Answer: C
Rationale: The microbiome includes bacteria, archaea, fungi, protozoa, and viruses that inhabit the
human body .
5. Which scientist is credited with first observing living microorganisms (“animalcules”) using a simple
microscope?
A) Robert Hooke
B) Louis Pasteur
C) Antonie van Leeuwenhoek
D) Robert Koch
Answer: C
Rationale: Leeuwenhoek made single-lens microscopes and was the first to describe bacteria and
protozoa, which he called "animalcules" .
6. The main difference between a prokaryotic and a eukaryotic cell is:
A) Presence of ribosomes
B) Presence of a nucleus and membrane-bound organelles
C) Ability to perform photosynthesis
D) Presence of a cell wall
Answer: B
Rationale: Prokaryotes lack a nucleus and membrane-bound organelles, which are defining features of
eukaryotic cells .
7. Which of the following is an example of a beneficial fermentation carried out by microbes?
A) Spoilage of milk
B) Production of yogurt
C) Bread molding
D) Wine turning to vinegar
Answer: B
Rationale: Yogurt is produced by bacterial fermentation (Lactobacillus species). The others are spoilage
or undesirable changes .
8. The process by which microbes convert atmospheric nitrogen (N₂) into ammonia (NH₃) is called:
A) Nitrification
B) Denitrification
C) Nitrogen fixation
D) Ammonification
Answer: C
Rationale: Nitrogen fixation is carried out by bacteria such as Rhizobium and Azotobacter, converting
inert atmospheric nitrogen into a biologically usable form .
9. Which of the following is a protozoan disease transmitted by insects?
A) Tuberculosis
B) Malaria
, C) Cholera
D) Tetanus
Answer: B
Rationale: Malaria is caused by Plasmodium (a protozoan) and transmitted by Anopheles mosquitoes .
10. The scientist who developed the first rabies vaccine and proposed the germ theory of disease was:
A) Robert Koch
B) Edward Jenner
C) Louis Pasteur
D) Joseph Lister
Answer: C
Rationale: Pasteur developed the rabies vaccine and pasteurization; Koch established postulates; Jenner
developed the smallpox vaccine; Lister introduced antiseptic surgery .
11. “Koch’s postulates” are used to:
A) Isolate pure cultures of bacteria
B) Prove that a specific microorganism causes a specific disease
C) Identify the presence of endotoxins
D) Determine antibiotic sensitivity
Answer: B
Rationale: The postulates provide a framework for linking a specific pathogen to a specific infectious
disease .
12. According to the concept of “syndemics,” diseases:
A) Occur only in epidemics
B) Interact and amplify each other within a population
C) Are always caused by single pathogens
D) Cannot be prevented by vaccines
Answer: B
Rationale: Syndemics consider biological and social factors that cause diseases to cluster and worsen
each other .
13. The human microbiome is best described as:
A) Sterile at birth and colonized after birth
B) Present only in the gut
C) Uniform across all individuals
D) The same as the human genome
Answer: A
Rationale: The infant acquires microbiota during and after birth; the composition varies between
individuals and body sites .
14. Which of the following is an example of a “friendly” E. coli strain?
A) O157:H7
Experience 3rd Edition by John Foster,
Zarrintaj Aliabadi
Exam
Chapter 1: Microbes Shape Our History (Q 1-25)
1. Which of the following is a beneficial role of microorganisms in the human body?
A) Production of vitamin K in the gut
B) Destruction of red blood cells
C) Formation of dental plaque
D) Causing urinary tract infections
Answer: A
Rationale: Gut bacteria synthesize vitamin K, which is essential for blood clotting. The other options are
harmful or pathological .
2. The three domains of life according to the Woese system are:
A) Prokaryota, Eukaryota, Fungi
B) Bacteria, Archaea, Eukarya
C) Plantae, Animalia, Protista
D) Monera, Protista, Fungi
Answer: B
Rationale: The three-domain system is based on ribosomal RNA analysis and includes Bacteria, Archaea,
and Eukarya .
3. Louis Pasteur’s swan-neck flask experiment demonstrated that:
A) Spontaneous generation is possible under certain conditions
B) Microbial life arises from pre-existing microbes (biogenesis)
C) Heat sterilization destroys all microbial life
D) Microbes are present in the air
Answer: B
Rationale: The experiment showed that broth remained sterile unless exposed to dust, disproving
spontaneous generation .
4. The human microbiome refers to:
A) The collection of all viruses in a human body
B) The total genetic content of a human
C) The aggregate of all microorganisms living in and on the human body
D) The set of all bacterial toxins
, Answer: C
Rationale: The microbiome includes bacteria, archaea, fungi, protozoa, and viruses that inhabit the
human body .
5. Which scientist is credited with first observing living microorganisms (“animalcules”) using a simple
microscope?
A) Robert Hooke
B) Louis Pasteur
C) Antonie van Leeuwenhoek
D) Robert Koch
Answer: C
Rationale: Leeuwenhoek made single-lens microscopes and was the first to describe bacteria and
protozoa, which he called "animalcules" .
6. The main difference between a prokaryotic and a eukaryotic cell is:
A) Presence of ribosomes
B) Presence of a nucleus and membrane-bound organelles
C) Ability to perform photosynthesis
D) Presence of a cell wall
Answer: B
Rationale: Prokaryotes lack a nucleus and membrane-bound organelles, which are defining features of
eukaryotic cells .
7. Which of the following is an example of a beneficial fermentation carried out by microbes?
A) Spoilage of milk
B) Production of yogurt
C) Bread molding
D) Wine turning to vinegar
Answer: B
Rationale: Yogurt is produced by bacterial fermentation (Lactobacillus species). The others are spoilage
or undesirable changes .
8. The process by which microbes convert atmospheric nitrogen (N₂) into ammonia (NH₃) is called:
A) Nitrification
B) Denitrification
C) Nitrogen fixation
D) Ammonification
Answer: C
Rationale: Nitrogen fixation is carried out by bacteria such as Rhizobium and Azotobacter, converting
inert atmospheric nitrogen into a biologically usable form .
9. Which of the following is a protozoan disease transmitted by insects?
A) Tuberculosis
B) Malaria
, C) Cholera
D) Tetanus
Answer: B
Rationale: Malaria is caused by Plasmodium (a protozoan) and transmitted by Anopheles mosquitoes .
10. The scientist who developed the first rabies vaccine and proposed the germ theory of disease was:
A) Robert Koch
B) Edward Jenner
C) Louis Pasteur
D) Joseph Lister
Answer: C
Rationale: Pasteur developed the rabies vaccine and pasteurization; Koch established postulates; Jenner
developed the smallpox vaccine; Lister introduced antiseptic surgery .
11. “Koch’s postulates” are used to:
A) Isolate pure cultures of bacteria
B) Prove that a specific microorganism causes a specific disease
C) Identify the presence of endotoxins
D) Determine antibiotic sensitivity
Answer: B
Rationale: The postulates provide a framework for linking a specific pathogen to a specific infectious
disease .
12. According to the concept of “syndemics,” diseases:
A) Occur only in epidemics
B) Interact and amplify each other within a population
C) Are always caused by single pathogens
D) Cannot be prevented by vaccines
Answer: B
Rationale: Syndemics consider biological and social factors that cause diseases to cluster and worsen
each other .
13. The human microbiome is best described as:
A) Sterile at birth and colonized after birth
B) Present only in the gut
C) Uniform across all individuals
D) The same as the human genome
Answer: A
Rationale: The infant acquires microbiota during and after birth; the composition varies between
individuals and body sites .
14. Which of the following is an example of a “friendly” E. coli strain?
A) O157:H7
