Prescott's Microbiology Exam/ All Actual Questions
with Correct Verified Answers/ All Chapters Covered/
Updated 2026 – Rated A+
1. Who is credited with the first observation of microorganisms
("animalcules") using a simple microscope?
• A. Louis Pasteur
• B. Robert Hooke
• C. Antonie van Leeuwenhoek
• D. Ferdinand Cohn
Correct Answer: C
Rationale: Antonie van Leeuwenhoek constructed single-lens
microscopes and was the first to observe and describe bacteria
and protozoa, which he called "animalcules." Robert Hooke
reported the cellular structure of plants and coined the term
"cell."
1
,2. Louis Pasteur's swan-neck flask experiment disproved which
theory?
• A. Biogenesis
• B. Cell theory
• C. Germ theory of disease
• D. Spontaneous generation
Correct Answer: D
Rationale: Pasteur's swan-neck flask experiment demonstrated
that broth remained sterile unless dust and microorganisms
entered the flask, providing strong evidence against spontaneous
generation. The flasks allowed air in but trapped dust and
microbes.
3. Robert Koch is best known for:
• A. Developing the smallpox vaccine
• B. Establishing Koch's postulates to link a specific
microorganism with a specific disease
2
, • C. Discovering penicillin
• D. Developing the Gram stain
Correct Answer: B
Rationale: Robert Koch developed a set of criteria (Koch's
postulates) to prove that a particular microbe causes a particular
disease. He also discovered the causative agents of anthrax,
tuberculosis, and cholera.
4. The first person to use a chemotherapeutic agent (Salvarsan)
to treat a bacterial infection was:
• A. Alexander Fleming
• B. Paul Ehrlich
• C. Gerhard Domagk
• D. Selman Waksman
Correct Answer: B
Rationale: Paul Ehrlich developed arsphenamine (Salvarsan) for
the treatment of syphilis, marking the beginning of
3
, chemotherapy. Fleming discovered penicillin, Domagk discovered
sulfa drugs, and Waksman discovered streptomycin.
5. The "golden age of microbiology" (roughly 1850–1915) was
characterized by:
• A. Development of recombinant DNA technology
• B. Discovery that microorganisms cause disease and
development of vaccines and aseptic techniques
• C. Discovery of antibiotics
• D. Development of the electron microscope
Correct Answer: B
Rationale: The golden age of microbiology was marked by the
discovery that microorganisms cause disease (Pasteur, Koch),
development of vaccines (Jenner, Pasteur), and aseptic
techniques (Lister). Antibiotics were discovered later, and
recombinant DNA technology and electron microscopy came in
the 20th century.
4
with Correct Verified Answers/ All Chapters Covered/
Updated 2026 – Rated A+
1. Who is credited with the first observation of microorganisms
("animalcules") using a simple microscope?
• A. Louis Pasteur
• B. Robert Hooke
• C. Antonie van Leeuwenhoek
• D. Ferdinand Cohn
Correct Answer: C
Rationale: Antonie van Leeuwenhoek constructed single-lens
microscopes and was the first to observe and describe bacteria
and protozoa, which he called "animalcules." Robert Hooke
reported the cellular structure of plants and coined the term
"cell."
1
,2. Louis Pasteur's swan-neck flask experiment disproved which
theory?
• A. Biogenesis
• B. Cell theory
• C. Germ theory of disease
• D. Spontaneous generation
Correct Answer: D
Rationale: Pasteur's swan-neck flask experiment demonstrated
that broth remained sterile unless dust and microorganisms
entered the flask, providing strong evidence against spontaneous
generation. The flasks allowed air in but trapped dust and
microbes.
3. Robert Koch is best known for:
• A. Developing the smallpox vaccine
• B. Establishing Koch's postulates to link a specific
microorganism with a specific disease
2
, • C. Discovering penicillin
• D. Developing the Gram stain
Correct Answer: B
Rationale: Robert Koch developed a set of criteria (Koch's
postulates) to prove that a particular microbe causes a particular
disease. He also discovered the causative agents of anthrax,
tuberculosis, and cholera.
4. The first person to use a chemotherapeutic agent (Salvarsan)
to treat a bacterial infection was:
• A. Alexander Fleming
• B. Paul Ehrlich
• C. Gerhard Domagk
• D. Selman Waksman
Correct Answer: B
Rationale: Paul Ehrlich developed arsphenamine (Salvarsan) for
the treatment of syphilis, marking the beginning of
3
, chemotherapy. Fleming discovered penicillin, Domagk discovered
sulfa drugs, and Waksman discovered streptomycin.
5. The "golden age of microbiology" (roughly 1850–1915) was
characterized by:
• A. Development of recombinant DNA technology
• B. Discovery that microorganisms cause disease and
development of vaccines and aseptic techniques
• C. Discovery of antibiotics
• D. Development of the electron microscope
Correct Answer: B
Rationale: The golden age of microbiology was marked by the
discovery that microorganisms cause disease (Pasteur, Koch),
development of vaccines (Jenner, Pasteur), and aseptic
techniques (Lister). Antibiotics were discovered later, and
recombinant DNA technology and electron microscopy came in
the 20th century.
4
