1
BIOD 171 MODULE 1 EXAM Actual Exam
2026/2027 Complete Questions and Verified Answers
with Detailed Rationales Essential Microbiology
Portage Learning Pass Guaranteed - A+ Graded
Section 1: Module 1 Exam
Q1: Which scientist is credited with disproving spontaneous generation through the use of swan-
neck flasks?
A. Robert Koch
B. Louis Pasteur [CORRECT]
C. Antonie van Leeuwenhoek
D. Joseph Lister
Correct Answer: B
Rationale: Louis Pasteur's experiments with swan-neck flasks in the 1860s demonstrated that
microorganisms in the air, not spontaneous generation, caused contamination of broth,
definitively refuting the theory of spontaneous generation.
Q2: The objective lens on a compound light microscope that provides the highest magnification
(typically 100x) and requires oil immersion is called the:
A. Scanning objective
B. Low power objective
C. High dry objective
D. Oil immersion objective [CORRECT]
Correct Answer: D
Rationale: The oil immersion objective (100x) uses immersion oil to reduce light refraction
between the slide and lens, achieving the highest magnification (total 1000x with 10x eyepiece)
and resolution for observing bacterial morphology.
Q3: Which of the following is NOT a domain in the three-domain system of classification?
A. Bacteria
B. Archaea
,2
C. Eukarya
D. Protista [CORRECT]
Correct Answer: D
Rationale: The three-domain system established by Carl Woese includes Bacteria, Archaea, and
Eukarya; Protista is a kingdom within the domain Eukarya, not a separate domain.
Q4: Antonie van Leeuwenhoek's contributions to microbiology include:
A. Developing the germ theory of disease
B. Constructing simple microscopes and observing "animalcules" in various samples
[CORRECT]
C. Establishing pure culture techniques
D. Developing pasteurization
Correct Answer: B
Rationale: Van Leeuwenhoek (1632-1723) crafted powerful single-lens microscopes and was the
first to observe and describe bacteria, protozoa, and other microorganisms, which he termed
"animalcules," in diverse environmental and bodily samples.
Q5: The total magnification of a compound light microscope is calculated by:
A. Adding the objective magnification to the eyepiece magnification
B. Multiplying the objective magnification by the eyepiece magnification [CORRECT]
C. Dividing the objective magnification by the eyepiece magnification
D. Subtracting the eyepiece magnification from the objective magnification
Correct Answer: B
Rationale: Total magnification equals objective lens magnification multiplied by ocular
(eyepiece) magnification; for example, a 40x objective with a 10x eyepiece produces 400x total
magnification.
Q6: Which structure in a prokaryotic cell is responsible for protein synthesis?
A. Nucleus
B. Ribosome [CORRECT]
C. Mitochondrion
D. Golgi apparatus
, 3
Correct Answer: B
Rationale: Ribosomes are the cellular structures responsible for translating mRNA into proteins;
prokaryotic ribosomes (70S) are smaller than eukaryotic ribosomes (80S) and are not membrane-
bound, existing free in the cytoplasm.
Q7: Robert Koch's postulates are used to:
A. Classify microorganisms into taxonomic groups
B. Determine the specific causative agent of an infectious disease [CORRECT]
C. Stain bacterial cells for microscopic observation
D. Measure bacterial growth rates
Correct Answer: B
Rationale: Koch's postulates provide a systematic framework for establishing a causal
relationship between a specific microorganism and a specific disease by requiring isolation,
cultivation, inoculation, and re-isolation of the suspected pathogen.
Q8: The resolving power of a microscope is defined as:
A. The ability to magnify an object
B. The ability to distinguish two adjacent objects as separate [CORRECT]
C. The brightness of the illumination system
D. The size of the field of view
Correct Answer: B
Rationale: Resolving power (resolution) is the minimum distance between two points at which
they can still be distinguished as separate entities; it is limited by the wavelength of light and the
numerical aperture of the lens.
Q9: Which type of microorganism is characterized by the absence of a membrane-bound nucleus
and organelles?
A. Fungi
B. Protozoa
C. Prokaryote [CORRECT]
D. Algae
Correct Answer: C
BIOD 171 MODULE 1 EXAM Actual Exam
2026/2027 Complete Questions and Verified Answers
with Detailed Rationales Essential Microbiology
Portage Learning Pass Guaranteed - A+ Graded
Section 1: Module 1 Exam
Q1: Which scientist is credited with disproving spontaneous generation through the use of swan-
neck flasks?
A. Robert Koch
B. Louis Pasteur [CORRECT]
C. Antonie van Leeuwenhoek
D. Joseph Lister
Correct Answer: B
Rationale: Louis Pasteur's experiments with swan-neck flasks in the 1860s demonstrated that
microorganisms in the air, not spontaneous generation, caused contamination of broth,
definitively refuting the theory of spontaneous generation.
Q2: The objective lens on a compound light microscope that provides the highest magnification
(typically 100x) and requires oil immersion is called the:
A. Scanning objective
B. Low power objective
C. High dry objective
D. Oil immersion objective [CORRECT]
Correct Answer: D
Rationale: The oil immersion objective (100x) uses immersion oil to reduce light refraction
between the slide and lens, achieving the highest magnification (total 1000x with 10x eyepiece)
and resolution for observing bacterial morphology.
Q3: Which of the following is NOT a domain in the three-domain system of classification?
A. Bacteria
B. Archaea
,2
C. Eukarya
D. Protista [CORRECT]
Correct Answer: D
Rationale: The three-domain system established by Carl Woese includes Bacteria, Archaea, and
Eukarya; Protista is a kingdom within the domain Eukarya, not a separate domain.
Q4: Antonie van Leeuwenhoek's contributions to microbiology include:
A. Developing the germ theory of disease
B. Constructing simple microscopes and observing "animalcules" in various samples
[CORRECT]
C. Establishing pure culture techniques
D. Developing pasteurization
Correct Answer: B
Rationale: Van Leeuwenhoek (1632-1723) crafted powerful single-lens microscopes and was the
first to observe and describe bacteria, protozoa, and other microorganisms, which he termed
"animalcules," in diverse environmental and bodily samples.
Q5: The total magnification of a compound light microscope is calculated by:
A. Adding the objective magnification to the eyepiece magnification
B. Multiplying the objective magnification by the eyepiece magnification [CORRECT]
C. Dividing the objective magnification by the eyepiece magnification
D. Subtracting the eyepiece magnification from the objective magnification
Correct Answer: B
Rationale: Total magnification equals objective lens magnification multiplied by ocular
(eyepiece) magnification; for example, a 40x objective with a 10x eyepiece produces 400x total
magnification.
Q6: Which structure in a prokaryotic cell is responsible for protein synthesis?
A. Nucleus
B. Ribosome [CORRECT]
C. Mitochondrion
D. Golgi apparatus
, 3
Correct Answer: B
Rationale: Ribosomes are the cellular structures responsible for translating mRNA into proteins;
prokaryotic ribosomes (70S) are smaller than eukaryotic ribosomes (80S) and are not membrane-
bound, existing free in the cytoplasm.
Q7: Robert Koch's postulates are used to:
A. Classify microorganisms into taxonomic groups
B. Determine the specific causative agent of an infectious disease [CORRECT]
C. Stain bacterial cells for microscopic observation
D. Measure bacterial growth rates
Correct Answer: B
Rationale: Koch's postulates provide a systematic framework for establishing a causal
relationship between a specific microorganism and a specific disease by requiring isolation,
cultivation, inoculation, and re-isolation of the suspected pathogen.
Q8: The resolving power of a microscope is defined as:
A. The ability to magnify an object
B. The ability to distinguish two adjacent objects as separate [CORRECT]
C. The brightness of the illumination system
D. The size of the field of view
Correct Answer: B
Rationale: Resolving power (resolution) is the minimum distance between two points at which
they can still be distinguished as separate entities; it is limited by the wavelength of light and the
numerical aperture of the lens.
Q9: Which type of microorganism is characterized by the absence of a membrane-bound nucleus
and organelles?
A. Fungi
B. Protozoa
C. Prokaryote [CORRECT]
D. Algae
Correct Answer: C
