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BIOD 171 Essential Microbiology Modules 1–6 Exam
& Final Exam (Latest 2026/2027 Update) Portage
learning/Geneva College
1. A microbiology student is comparing bacterial cells with human cells
and notices that bacterial DNA is not enclosed within a membrane-
bound nucleus. Which structural characteristic most accurately explains
this difference?
A. Bacterial cells contain mitochondria instead of ribosomes.
B. Bacterial cells are prokaryotic and therefore lack a membrane-bound
nucleus.
C. Human cells are prokaryotic and bacteria are eukaryotic.
D. Bacterial cells lack genetic material because they reproduce by binary
fission.
Answer: B
2. Which group represents the four major classes of biological
macromolecules found in cells?
A. Proteins, lipids, nucleic acids, and carbohydrates
B. Water, minerals, vitamins, and ATP
C. DNA, RNA, ATP, and glucose
D. Amino acids, fatty acids, nucleotides, and minerals
Answer: A
3. A bacterial cell is placed in a solution that has a substantially higher
solute concentration than the cytoplasm. Assuming the solutes cannot
freely cross the membrane, what will most likely happen?
A. Water moves into the cell, causing it to swell.
B. Water moves out of the cell, causing the cell to lose water.
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C. Solutes immediately leave the cell through passive transport.
D. ATP production stops because water cannot cross the membrane.
Answer: B
4. Which transport mechanism requires cellular energy because
substances are moved against their concentration or electrochemical
gradient?
A. Simple diffusion
B. Osmosis
C. Facilitated diffusion
D. Active transport
Answer: D
5. A bacterial cell is exposed to a substance that damages peptidoglycan.
Which cellular structure is most directly affected?
A. Bacterial cell wall
B. Cytoplasmic membrane
C. Ribosome
D. Nucleoid
Answer: A
6. Which statement best distinguishes bacterial cells from eukaryotic
cells?
A. Bacteria contain DNA whereas eukaryotic cells do not.
B. Bacteria generally lack membrane-bound organelles such as
mitochondria and a nucleus.
C. Eukaryotic cells contain ribosomes whereas bacteria do not.
D. Bacteria are always multicellular organisms.
Answer: B
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7. A microbiologist wants to determine the basic shape and arrangement
of bacterial cells before performing more specialized testing. Which
technique would provide a straightforward initial observation?
A. Simple staining
B. Acid-fast staining
C. Endospore staining
D. Viral plaque assay
Answer: A
8. A patient is suspected of having tuberculosis. Which staining
procedure is particularly useful because Mycobacterium species possess
waxy, lipid-rich cell walls?
A. Gram stain
B. Acid-fast stain
C. Endospore stain
D. Negative stain
Answer: B
9. During a Gram stain, bacteria that retain crystal violet and appear
purple are classified as:
A. Gram-negative
B. Acid-fast
C. Gram-positive
D. Spore-forming
Answer: C
10. Which structural feature primarily explains why Gram-positive
bacteria retain the crystal violet–iodine complex during Gram staining?
A. A thick peptidoglycan layer
B. An outer membrane containing lipopolysaccharide
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C. A complete absence of a cell wall
D. A large capsule surrounding the cytoplasmic membrane
Answer: A
11. A Gram-negative bacterial cell differs from a Gram-positive cell
because Gram-negative bacteria possess:
A. No peptidoglycan at all.
B. A thick peptidoglycan layer without an outer membrane.
C. An outer membrane containing lipopolysaccharide and a relatively
thin peptidoglycan layer.
D. A membrane-bound nucleus.
Answer: C
12. A microbiologist performs a quadrant streak on an agar plate. What
is the primary purpose of this technique?
A. To increase the total number of bacterial species present
B. To obtain isolated colonies from a mixed or concentrated bacterial
population
C. To determine whether bacteria are Gram-positive
D. To eliminate all microorganisms from the culture
Answer: B
13. A culture is considered a pure culture when:
A. It contains a very large number of bacterial cells.
B. It contains only one identifiable microbial species and is free from
contaminating organisms.
C. It contains only Gram-positive organisms.
D. It has been incubated for at least 24 hours.
Answer: B
BIOD 171 Essential Microbiology Modules 1–6 Exam
& Final Exam (Latest 2026/2027 Update) Portage
learning/Geneva College
1. A microbiology student is comparing bacterial cells with human cells
and notices that bacterial DNA is not enclosed within a membrane-
bound nucleus. Which structural characteristic most accurately explains
this difference?
A. Bacterial cells contain mitochondria instead of ribosomes.
B. Bacterial cells are prokaryotic and therefore lack a membrane-bound
nucleus.
C. Human cells are prokaryotic and bacteria are eukaryotic.
D. Bacterial cells lack genetic material because they reproduce by binary
fission.
Answer: B
2. Which group represents the four major classes of biological
macromolecules found in cells?
A. Proteins, lipids, nucleic acids, and carbohydrates
B. Water, minerals, vitamins, and ATP
C. DNA, RNA, ATP, and glucose
D. Amino acids, fatty acids, nucleotides, and minerals
Answer: A
3. A bacterial cell is placed in a solution that has a substantially higher
solute concentration than the cytoplasm. Assuming the solutes cannot
freely cross the membrane, what will most likely happen?
A. Water moves into the cell, causing it to swell.
B. Water moves out of the cell, causing the cell to lose water.
,2|Page
C. Solutes immediately leave the cell through passive transport.
D. ATP production stops because water cannot cross the membrane.
Answer: B
4. Which transport mechanism requires cellular energy because
substances are moved against their concentration or electrochemical
gradient?
A. Simple diffusion
B. Osmosis
C. Facilitated diffusion
D. Active transport
Answer: D
5. A bacterial cell is exposed to a substance that damages peptidoglycan.
Which cellular structure is most directly affected?
A. Bacterial cell wall
B. Cytoplasmic membrane
C. Ribosome
D. Nucleoid
Answer: A
6. Which statement best distinguishes bacterial cells from eukaryotic
cells?
A. Bacteria contain DNA whereas eukaryotic cells do not.
B. Bacteria generally lack membrane-bound organelles such as
mitochondria and a nucleus.
C. Eukaryotic cells contain ribosomes whereas bacteria do not.
D. Bacteria are always multicellular organisms.
Answer: B
,3|Page
7. A microbiologist wants to determine the basic shape and arrangement
of bacterial cells before performing more specialized testing. Which
technique would provide a straightforward initial observation?
A. Simple staining
B. Acid-fast staining
C. Endospore staining
D. Viral plaque assay
Answer: A
8. A patient is suspected of having tuberculosis. Which staining
procedure is particularly useful because Mycobacterium species possess
waxy, lipid-rich cell walls?
A. Gram stain
B. Acid-fast stain
C. Endospore stain
D. Negative stain
Answer: B
9. During a Gram stain, bacteria that retain crystal violet and appear
purple are classified as:
A. Gram-negative
B. Acid-fast
C. Gram-positive
D. Spore-forming
Answer: C
10. Which structural feature primarily explains why Gram-positive
bacteria retain the crystal violet–iodine complex during Gram staining?
A. A thick peptidoglycan layer
B. An outer membrane containing lipopolysaccharide
, 4|Page
C. A complete absence of a cell wall
D. A large capsule surrounding the cytoplasmic membrane
Answer: A
11. A Gram-negative bacterial cell differs from a Gram-positive cell
because Gram-negative bacteria possess:
A. No peptidoglycan at all.
B. A thick peptidoglycan layer without an outer membrane.
C. An outer membrane containing lipopolysaccharide and a relatively
thin peptidoglycan layer.
D. A membrane-bound nucleus.
Answer: C
12. A microbiologist performs a quadrant streak on an agar plate. What
is the primary purpose of this technique?
A. To increase the total number of bacterial species present
B. To obtain isolated colonies from a mixed or concentrated bacterial
population
C. To determine whether bacteria are Gram-positive
D. To eliminate all microorganisms from the culture
Answer: B
13. A culture is considered a pure culture when:
A. It contains a very large number of bacterial cells.
B. It contains only one identifiable microbial species and is free from
contaminating organisms.
C. It contains only Gram-positive organisms.
D. It has been incubated for at least 24 hours.
Answer: B
