MICROBIOLOGY • MODULE 1
BIOL 271 / BIOL271 Module 1:
(Latest 2026/2027 Update) 100% Verified
Questions & Answers | Grade A
**2026/2027** — 2026/2027 A+
Complete Blueprint Coverage • Microbial World & Cell Biology Review
A+ 5 100%
QUESTIONS VERIFIED EXAM DOMAINS COVERED RATIONALES INCLUDED
CATEGORIES
I. The Microbial World & Classification
II. Biological Macromolecules
III. Prokaryotic Cell Structure
IV. Eukaryotic Cell Structure & Organelles
V. Comparative Cell Biology & Applications
STUVIAACTUALEXAM
, SECTION I — THE MICROBIAL WORLD & CLASSIFICATION
1 A student examines a soil sample under a microscope and observes cells that lack a membrane-bound nucleus and
contain circular DNA. These organisms are best classified as:
A. Prokaryotes
B. Eukaryotes
C. Viruses
D. Prions
Correct Answer: A
Rationale: Prokaryotic cells are defined by the absence of a membrane-bound nucleus and the presence of a single circular chromosome
(nucleoid). Eukaryotes possess a true nucleus.
2 While reviewing the three-domain system of classification, a microbiologist notes that Archaea share certain molecular
features with eukaryotes yet morphologically resemble bacteria. The feature that places Archaea in their own domain is
primarily:
A. Unique ribosomal RNA sequences and distinctive membrane lipids
B. Presence of a peptidoglycan cell wall identical to bacteria
C. Possession of membrane-bound organelles
D. Ability to form spores identical to bacterial endospores
Correct Answer: A
Rationale: Archaea are distinguished by unique rRNA sequences and ether-linked membrane lipids; they lack peptidoglycan and do not
possess membrane-bound organelles.
3 A laboratory receives a clinical specimen containing an acellular infectious agent composed only of protein. This agent
is most accurately described as a:
A. Bacterium
B. Prion
C. Viroid
D. Virus
Correct Answer: B
Rationale: Prions are infectious proteins that lack nucleic acid. Viroids are naked RNA molecules; viruses contain nucleic acid enclosed in a
protein coat.
4 A researcher isolates an organism that obtains energy by oxidizing inorganic compounds and fixes carbon dioxide. This
nutritional mode is termed:
A. Photoheterotrophy
B. Photoautotrophy using only organic carbon
C. Chemoorganoheterotrophy
D. Chemolithoautotrophy
Correct Answer: D
Rationale: Chemolithoautotrophs derive energy from inorganic chemical reactions and use CO2 as their carbon source, a strategy common
among certain bacteria and archaea.
5 In the historical development of microbiology, the experiment that most directly refuted spontaneous generation using
swan-necked flasks was performed by:
A. Joseph Lister
B. Robert Koch
C. Antonie van Leeuwenhoek
D. Louis Pasteur
Correct Answer: D
Rationale: Pasteur's swan-neck flask experiments demonstrated that sterilized broth remained sterile unless exposed to airborne microbes,
disproving spontaneous generation.
BIOL 271 / BIOL271 Module 1:
(Latest 2026/2027 Update) 100% Verified
Questions & Answers | Grade A
**2026/2027** — 2026/2027 A+
Complete Blueprint Coverage • Microbial World & Cell Biology Review
A+ 5 100%
QUESTIONS VERIFIED EXAM DOMAINS COVERED RATIONALES INCLUDED
CATEGORIES
I. The Microbial World & Classification
II. Biological Macromolecules
III. Prokaryotic Cell Structure
IV. Eukaryotic Cell Structure & Organelles
V. Comparative Cell Biology & Applications
STUVIAACTUALEXAM
, SECTION I — THE MICROBIAL WORLD & CLASSIFICATION
1 A student examines a soil sample under a microscope and observes cells that lack a membrane-bound nucleus and
contain circular DNA. These organisms are best classified as:
A. Prokaryotes
B. Eukaryotes
C. Viruses
D. Prions
Correct Answer: A
Rationale: Prokaryotic cells are defined by the absence of a membrane-bound nucleus and the presence of a single circular chromosome
(nucleoid). Eukaryotes possess a true nucleus.
2 While reviewing the three-domain system of classification, a microbiologist notes that Archaea share certain molecular
features with eukaryotes yet morphologically resemble bacteria. The feature that places Archaea in their own domain is
primarily:
A. Unique ribosomal RNA sequences and distinctive membrane lipids
B. Presence of a peptidoglycan cell wall identical to bacteria
C. Possession of membrane-bound organelles
D. Ability to form spores identical to bacterial endospores
Correct Answer: A
Rationale: Archaea are distinguished by unique rRNA sequences and ether-linked membrane lipids; they lack peptidoglycan and do not
possess membrane-bound organelles.
3 A laboratory receives a clinical specimen containing an acellular infectious agent composed only of protein. This agent
is most accurately described as a:
A. Bacterium
B. Prion
C. Viroid
D. Virus
Correct Answer: B
Rationale: Prions are infectious proteins that lack nucleic acid. Viroids are naked RNA molecules; viruses contain nucleic acid enclosed in a
protein coat.
4 A researcher isolates an organism that obtains energy by oxidizing inorganic compounds and fixes carbon dioxide. This
nutritional mode is termed:
A. Photoheterotrophy
B. Photoautotrophy using only organic carbon
C. Chemoorganoheterotrophy
D. Chemolithoautotrophy
Correct Answer: D
Rationale: Chemolithoautotrophs derive energy from inorganic chemical reactions and use CO2 as their carbon source, a strategy common
among certain bacteria and archaea.
5 In the historical development of microbiology, the experiment that most directly refuted spontaneous generation using
swan-necked flasks was performed by:
A. Joseph Lister
B. Robert Koch
C. Antonie van Leeuwenhoek
D. Louis Pasteur
Correct Answer: D
Rationale: Pasteur's swan-neck flask experiments demonstrated that sterilized broth remained sterile unless exposed to airborne microbes,
disproving spontaneous generation.
