WGU D311 – Microbiology Objective Assessment (OA) |
Complete Exam Questions with Verified Correct Answers and
Detailed Rationale – Latest Update 2026/2027 | Graded A+
Question 1
Microbiology is the study of:
A. Only human anatomy and physiology.
B. Microscopic organisms, including bacteria, viruses, fungi, protozoa, and
other microorganisms.
C. Only plants and animals visible to the human eye.
D. Chemical reactions occurring only inside cells.
Correct Answer: B. Microscopic organisms, including bacteria, viruses,
fungi, protozoa, and other microorganisms.
Rationale:
Microbiology focuses on microorganisms and their interactions with humans,
animals, plants, and the environment. It includes the study of bacteria, viruses,
fungi, parasites, and microscopic algae.
Question 2
Which scientist is known for developing the germ theory of disease?
A. Louis Pasteur.
B. Gregor Mendel.
C. Charles Darwin.
D. Robert Hooke.
1|Page
,Correct Answer: A. Louis Pasteur.
Rationale:
Louis Pasteur demonstrated that microorganisms cause disease and
contributed greatly to germ theory, pasteurization, and vaccine development.
Question 3
Which scientist discovered penicillin?
A. Alexander Fleming.
B. Antonie van Leeuwenhoek.
C. Edward Jenner.
D. Joseph Lister.
Correct Answer: A. Alexander Fleming.
Rationale:
Alexander Fleming discovered penicillin in 1928, leading to the development
of antibiotics used to treat bacterial infections.
Question 4
Which structure is found in bacterial cells but not animal cells?
A. Cell wall.
B. Nucleus.
C. Mitochondria.
D. Endoplasmic reticulum.
Correct Answer: A. Cell wall.
2|Page
,Rationale:
Bacteria are prokaryotic cells and often contain a rigid cell wall made of
peptidoglycan. Animal cells lack cell walls.
Question 5
Bacteria are classified as:
A. Prokaryotes because they lack a membrane-bound nucleus.
B. Eukaryotes because they contain organelles.
C. Viruses because they require hosts.
D. Multicellular organisms.
Correct Answer: A. Prokaryotes because they lack a membrane-bound
nucleus.
Rationale:
Prokaryotic cells do not have a true nucleus or membrane-bound organelles.
Their DNA is located in a nucleoid region.
Question 6
Which structure allows bacteria to move?
A. Flagella.
B. Ribosomes.
C. Capsule.
D. Cell wall.
Correct Answer: A. Flagella.
3|Page
, Rationale:
Flagella are whip-like structures that provide bacterial movement through
rotation.
Question 7
What is the primary function of bacterial ribosomes?
A. Protein synthesis.
B. DNA storage.
C. Cell movement.
D. Energy production.
Correct Answer: A. Protein synthesis.
Rationale:
Ribosomes translate genetic information into proteins necessary for bacterial
growth and survival.
Question 8
Which bacterial shape is spherical?
A. Cocci.
B. Bacilli.
C. Spirilla.
D. Vibrios.
Correct Answer: A. Cocci.
4|Page
Complete Exam Questions with Verified Correct Answers and
Detailed Rationale – Latest Update 2026/2027 | Graded A+
Question 1
Microbiology is the study of:
A. Only human anatomy and physiology.
B. Microscopic organisms, including bacteria, viruses, fungi, protozoa, and
other microorganisms.
C. Only plants and animals visible to the human eye.
D. Chemical reactions occurring only inside cells.
Correct Answer: B. Microscopic organisms, including bacteria, viruses,
fungi, protozoa, and other microorganisms.
Rationale:
Microbiology focuses on microorganisms and their interactions with humans,
animals, plants, and the environment. It includes the study of bacteria, viruses,
fungi, parasites, and microscopic algae.
Question 2
Which scientist is known for developing the germ theory of disease?
A. Louis Pasteur.
B. Gregor Mendel.
C. Charles Darwin.
D. Robert Hooke.
1|Page
,Correct Answer: A. Louis Pasteur.
Rationale:
Louis Pasteur demonstrated that microorganisms cause disease and
contributed greatly to germ theory, pasteurization, and vaccine development.
Question 3
Which scientist discovered penicillin?
A. Alexander Fleming.
B. Antonie van Leeuwenhoek.
C. Edward Jenner.
D. Joseph Lister.
Correct Answer: A. Alexander Fleming.
Rationale:
Alexander Fleming discovered penicillin in 1928, leading to the development
of antibiotics used to treat bacterial infections.
Question 4
Which structure is found in bacterial cells but not animal cells?
A. Cell wall.
B. Nucleus.
C. Mitochondria.
D. Endoplasmic reticulum.
Correct Answer: A. Cell wall.
2|Page
,Rationale:
Bacteria are prokaryotic cells and often contain a rigid cell wall made of
peptidoglycan. Animal cells lack cell walls.
Question 5
Bacteria are classified as:
A. Prokaryotes because they lack a membrane-bound nucleus.
B. Eukaryotes because they contain organelles.
C. Viruses because they require hosts.
D. Multicellular organisms.
Correct Answer: A. Prokaryotes because they lack a membrane-bound
nucleus.
Rationale:
Prokaryotic cells do not have a true nucleus or membrane-bound organelles.
Their DNA is located in a nucleoid region.
Question 6
Which structure allows bacteria to move?
A. Flagella.
B. Ribosomes.
C. Capsule.
D. Cell wall.
Correct Answer: A. Flagella.
3|Page
, Rationale:
Flagella are whip-like structures that provide bacterial movement through
rotation.
Question 7
What is the primary function of bacterial ribosomes?
A. Protein synthesis.
B. DNA storage.
C. Cell movement.
D. Energy production.
Correct Answer: A. Protein synthesis.
Rationale:
Ribosomes translate genetic information into proteins necessary for bacterial
growth and survival.
Question 8
Which bacterial shape is spherical?
A. Cocci.
B. Bacilli.
C. Spirilla.
D. Vibrios.
Correct Answer: A. Cocci.
4|Page
