General Microbiology Final Exam Questions
with Correct Answers 2025/2026
Which of the following are included in the category "microorganisms"?
A) Viruses
B) Yeasts (fungi)
C) Ticks
D) A and B
E) All of the above - CORRECT ANSWER -Viruses and Yeasts
"Spontaneous Generation" means: - CORRECT ANSWER -nonliving matter gives rise to living
organisms
Who is credited with first observing living microorganisms? - CORRECT ANSWER -Anton van
Leeuwenhoek
Proponents of the theory of spontaneous generation criticized Louis Jablot's experiment with
sealed flasks of broth because: - CORRECT ANSWER -No air was allowed to reach the broth
Who discovered that DNA is the molecule of genetic heredity? - CORRECT ANSWER -Avery,
McCloud, and MacCarty
True or False: Koch's Postulates can be fulfilled for every disease that's caused by
microorganisms (as long as it's culturable) - CORRECT ANSWER -True
Who performed an early experiment, with covered and uncovered pieces of meat, that
weakened the theory of spontaneous generation? - CORRECT ANSWER -Francesco Redi
,The first step for directly linking a microbe to a specific disease according to Koch's postulates is
to - CORRECT ANSWER -find the microbe in all diseased animals, but no healthy ones
In the name "Staphylococcus aureus", "Staphylococcus" is the: - CORRECT ANSWER -genus
What key aspect of Pasteur's experiment with the S-necked flasks made it more convincing than
previous experiments in the argument against spontaneous generation? - CORRECT ANSWER -In
Pasteur's experiment, air was allowed to reach the broth unaltered
What is the total magnification of a specimen viewed with a 15x ocular lens and a 10x objective
lens? - CORRECT ANSWER -150x
True or False: Technological improvements in lens-making may someday allow us to see viruses
with light microscopes - CORRECT ANSWER -False
Which of the following resolutions would best allow you to distinguish fine detail in a specimen?
A) 0.2 um
B) 2 um
C) 0.2 mm
D) 2 mm - CORRECT ANSWER -0.2 um
A microorganism measures 5 um in length. Its length in mm would be: - CORRECT ANSWER -
0.005 mm
You are performing a gram stain on gram-positive bacteria and you stop after the addition of the
decolorizer (acetone-alcohol). What is the appearance of the bacteria at this point? - CORRECT
ANSWER -Purple
, Which microscope is used to observe viruses and the internal structure of thinly sectioned cells?
- CORRECT ANSWER -Transmission electron microscope
Assume you stain a bacterial smear by applying carbolfuschin with heat and then
counterstaining with methylene blue. Through the microscope, the organisms that appear red
are: - CORRECT ANSWER -Acid-fast
Which step in the gram stain is the critical step in differentiating gram-positive cells from gram-
negative cells? - CORRECT ANSWER -Alcohol-acetone
True or False: A student has obtained a sample of pond water for study. Using the high-power
lens, he observes several cells with nuclei. He can conclude that the cells are NOT bacteria. -
CORRECT ANSWER -True
A prokaryotic cell may possess each of the following cellular components EXCEPT:
A) Mitochondria
B) Pili
C) Ribosomes
D) A cell membrane - CORRECT ANSWER -Mitochondria
Bacteria of the shape shown would be described as: - CORRECT ANSWER -Spirilli
Bacteria with the shape and arrangement shown would be described as: - CORRECT ANSWER -
Streptobacilli
A firmly-attached, tightly-organized glycocalyx, used for protection against phagocytosis, is a: -
CORRECT ANSWER -Capsule
with Correct Answers 2025/2026
Which of the following are included in the category "microorganisms"?
A) Viruses
B) Yeasts (fungi)
C) Ticks
D) A and B
E) All of the above - CORRECT ANSWER -Viruses and Yeasts
"Spontaneous Generation" means: - CORRECT ANSWER -nonliving matter gives rise to living
organisms
Who is credited with first observing living microorganisms? - CORRECT ANSWER -Anton van
Leeuwenhoek
Proponents of the theory of spontaneous generation criticized Louis Jablot's experiment with
sealed flasks of broth because: - CORRECT ANSWER -No air was allowed to reach the broth
Who discovered that DNA is the molecule of genetic heredity? - CORRECT ANSWER -Avery,
McCloud, and MacCarty
True or False: Koch's Postulates can be fulfilled for every disease that's caused by
microorganisms (as long as it's culturable) - CORRECT ANSWER -True
Who performed an early experiment, with covered and uncovered pieces of meat, that
weakened the theory of spontaneous generation? - CORRECT ANSWER -Francesco Redi
,The first step for directly linking a microbe to a specific disease according to Koch's postulates is
to - CORRECT ANSWER -find the microbe in all diseased animals, but no healthy ones
In the name "Staphylococcus aureus", "Staphylococcus" is the: - CORRECT ANSWER -genus
What key aspect of Pasteur's experiment with the S-necked flasks made it more convincing than
previous experiments in the argument against spontaneous generation? - CORRECT ANSWER -In
Pasteur's experiment, air was allowed to reach the broth unaltered
What is the total magnification of a specimen viewed with a 15x ocular lens and a 10x objective
lens? - CORRECT ANSWER -150x
True or False: Technological improvements in lens-making may someday allow us to see viruses
with light microscopes - CORRECT ANSWER -False
Which of the following resolutions would best allow you to distinguish fine detail in a specimen?
A) 0.2 um
B) 2 um
C) 0.2 mm
D) 2 mm - CORRECT ANSWER -0.2 um
A microorganism measures 5 um in length. Its length in mm would be: - CORRECT ANSWER -
0.005 mm
You are performing a gram stain on gram-positive bacteria and you stop after the addition of the
decolorizer (acetone-alcohol). What is the appearance of the bacteria at this point? - CORRECT
ANSWER -Purple
, Which microscope is used to observe viruses and the internal structure of thinly sectioned cells?
- CORRECT ANSWER -Transmission electron microscope
Assume you stain a bacterial smear by applying carbolfuschin with heat and then
counterstaining with methylene blue. Through the microscope, the organisms that appear red
are: - CORRECT ANSWER -Acid-fast
Which step in the gram stain is the critical step in differentiating gram-positive cells from gram-
negative cells? - CORRECT ANSWER -Alcohol-acetone
True or False: A student has obtained a sample of pond water for study. Using the high-power
lens, he observes several cells with nuclei. He can conclude that the cells are NOT bacteria. -
CORRECT ANSWER -True
A prokaryotic cell may possess each of the following cellular components EXCEPT:
A) Mitochondria
B) Pili
C) Ribosomes
D) A cell membrane - CORRECT ANSWER -Mitochondria
Bacteria of the shape shown would be described as: - CORRECT ANSWER -Spirilli
Bacteria with the shape and arrangement shown would be described as: - CORRECT ANSWER -
Streptobacilli
A firmly-attached, tightly-organized glycocalyx, used for protection against phagocytosis, is a: -
CORRECT ANSWER -Capsule
