MIBO 3500 Final Exam questions with
correct answers 2026/2027 Updated.
Microbial size definition - correct answer -organisms and acellular agents too small to be seen by the
unaided eye
contradictions to this definition - correct answer --supersize microbial cells
-microbial communities
-viruses
You are caring for a patient actively infected with
Mycobacterium tuberculosis.
Size of contaminated respiratory droplets are 1000- 5000 nm in size. Standard surgical masks are
designed to block particles larger than 5 μm. Will wearing a
standard surgical mask be an effective form of
protection? - correct answer -No, the mask protects against microbes that are 1-5 nanometers, and the
tuberculosis particles are larger than 5 nanometers
Robert Hooke - correct answer --built first compound microscope to observe mole and cork
-published Micrographia
-coined the term "cell"
Antoine van Leeuwenhoek - correct answer --built single lens magnifiers
-first to observe single-celled microbes, called them "small animals"
Francesco Redi - correct answer -performed an experiment disproving spontaneous generation in which
he had meat in a container with no cover, one with a paper cover, and one with a gauze cover
Lazzaro Spallanzani - correct answer -disproved spontaneous generation by boiling broth and either
covering it or not covering it. Observed microbial presence in broth that had no cover only
,Louis Pasteur - correct answer -disproved spontaneous generation using broth and bottle-neck
experiment
spontaneous generation - correct answer -living organisms can arise from non-living matter
Germ theory - correct answer -the theory that many diseases are caused by microbes (chain of infection,
pure culture, colonies)
Chain of infection - correct answer -transmission of infectious microbes
Pure culture - correct answer -culture from a single parental cell
Colonies - correct answer -distinct populations each grown from a single cell
Robert Koch - correct answer -Developed first guidelines (postulates) to establish a link between a
specific microbe and disease
Koch's postulates (4) - correct answer -1) Microorganism must be present in every case of the disease
and absent from healthy organisms
2) Microbe must be isolated/grown in pure culture
3) Same disease must result when microbe is inoculated in healthy host
4) Same microorganism must be able to be isolated from the host in which inoculation caused disease
Florence Nightingale - correct answer -the first to use medical statistics to demonstrate the significance
of mortality due to disease
Alexander Fleming - correct answer -discovered that Penicillium mold generated a substance that can
kill bacteria
,Howard Florey and Ernst Chain - correct answer -purified penicillin, first commercial antibiotic to save
lives
Sergei Winogradsky - correct answer -among the first to study microbes in natural habitats, discovered
lithotrophis, and developed enrichment cultures. ALso build Winogradsky column
Resolution - correct answer -the ability to distinguish small objects close together
Magnification - correct answer -enlarged image of an object
Contrast - correct answer -the difference in color intensity between an object and its background
4 types of light microscopes - correct answer -bright-field
dark-field
phase-contrast
fluorescence
Compound microscope - correct answer -a microscope that forms an image from more than two lenses
Images produced by bright field microscopes are real or virtual? - correct answer -virtual
Bright-field microscopy - correct answer --used to see small bacteria but cannot be used to see smaller
microbes like viruses. Shows cells in colorless fashion. Staining of cells usually kills them and ligt
refraction is also problematic
Refraction - correct answer -bending of light as it passes through an object that slows its speed
Dark-field microscopy - correct answer --dark field optics enable microbes to be visualized as halos of
light against darkness
-allows detection of narrow cells (0.1 nano) that are unresolved by bright-field microscopy
, Phase-contrast microscopy - correct answer -refractive differences in cell components are transformed
into differences in light intensity
Fluorescence microscopy - correct answer -For specimens with added dye, or naturally photosynthetic
microbes, this way shows bright colored image of object, protein, or structure. Widely used in medical
microbiology and ecology
Fluorophores - correct answer -chemical compounds that absorb/emit light of specific wavelengths, can
be a dye or a protein
Why do researchers stain microbes? - correct answer --increases visibility
-preserves sample
-highlights morphological features
Heat fixation - correct answer -uses flame to preserve internal and external morphology but inactivates
enzymes
Chemical fixation - correct answer -uses ethanol, preseves morphology of microbe but may also
inactivate enzymes
basic dyes - correct answer -have a POSITIVE charge and bind to negatively charged molecules, such as
nucleic acids or bacterial surfaces
3 basic dyes - correct answer --methylene blue
-crystal violet
-safranin
Acidic dyes - correct answer -have a negative charge that binds to positively charged molecules, such as
tissue
2 acidic dyes - correct answer -eosin and nigrosin
correct answers 2026/2027 Updated.
Microbial size definition - correct answer -organisms and acellular agents too small to be seen by the
unaided eye
contradictions to this definition - correct answer --supersize microbial cells
-microbial communities
-viruses
You are caring for a patient actively infected with
Mycobacterium tuberculosis.
Size of contaminated respiratory droplets are 1000- 5000 nm in size. Standard surgical masks are
designed to block particles larger than 5 μm. Will wearing a
standard surgical mask be an effective form of
protection? - correct answer -No, the mask protects against microbes that are 1-5 nanometers, and the
tuberculosis particles are larger than 5 nanometers
Robert Hooke - correct answer --built first compound microscope to observe mole and cork
-published Micrographia
-coined the term "cell"
Antoine van Leeuwenhoek - correct answer --built single lens magnifiers
-first to observe single-celled microbes, called them "small animals"
Francesco Redi - correct answer -performed an experiment disproving spontaneous generation in which
he had meat in a container with no cover, one with a paper cover, and one with a gauze cover
Lazzaro Spallanzani - correct answer -disproved spontaneous generation by boiling broth and either
covering it or not covering it. Observed microbial presence in broth that had no cover only
,Louis Pasteur - correct answer -disproved spontaneous generation using broth and bottle-neck
experiment
spontaneous generation - correct answer -living organisms can arise from non-living matter
Germ theory - correct answer -the theory that many diseases are caused by microbes (chain of infection,
pure culture, colonies)
Chain of infection - correct answer -transmission of infectious microbes
Pure culture - correct answer -culture from a single parental cell
Colonies - correct answer -distinct populations each grown from a single cell
Robert Koch - correct answer -Developed first guidelines (postulates) to establish a link between a
specific microbe and disease
Koch's postulates (4) - correct answer -1) Microorganism must be present in every case of the disease
and absent from healthy organisms
2) Microbe must be isolated/grown in pure culture
3) Same disease must result when microbe is inoculated in healthy host
4) Same microorganism must be able to be isolated from the host in which inoculation caused disease
Florence Nightingale - correct answer -the first to use medical statistics to demonstrate the significance
of mortality due to disease
Alexander Fleming - correct answer -discovered that Penicillium mold generated a substance that can
kill bacteria
,Howard Florey and Ernst Chain - correct answer -purified penicillin, first commercial antibiotic to save
lives
Sergei Winogradsky - correct answer -among the first to study microbes in natural habitats, discovered
lithotrophis, and developed enrichment cultures. ALso build Winogradsky column
Resolution - correct answer -the ability to distinguish small objects close together
Magnification - correct answer -enlarged image of an object
Contrast - correct answer -the difference in color intensity between an object and its background
4 types of light microscopes - correct answer -bright-field
dark-field
phase-contrast
fluorescence
Compound microscope - correct answer -a microscope that forms an image from more than two lenses
Images produced by bright field microscopes are real or virtual? - correct answer -virtual
Bright-field microscopy - correct answer --used to see small bacteria but cannot be used to see smaller
microbes like viruses. Shows cells in colorless fashion. Staining of cells usually kills them and ligt
refraction is also problematic
Refraction - correct answer -bending of light as it passes through an object that slows its speed
Dark-field microscopy - correct answer --dark field optics enable microbes to be visualized as halos of
light against darkness
-allows detection of narrow cells (0.1 nano) that are unresolved by bright-field microscopy
, Phase-contrast microscopy - correct answer -refractive differences in cell components are transformed
into differences in light intensity
Fluorescence microscopy - correct answer -For specimens with added dye, or naturally photosynthetic
microbes, this way shows bright colored image of object, protein, or structure. Widely used in medical
microbiology and ecology
Fluorophores - correct answer -chemical compounds that absorb/emit light of specific wavelengths, can
be a dye or a protein
Why do researchers stain microbes? - correct answer --increases visibility
-preserves sample
-highlights morphological features
Heat fixation - correct answer -uses flame to preserve internal and external morphology but inactivates
enzymes
Chemical fixation - correct answer -uses ethanol, preseves morphology of microbe but may also
inactivate enzymes
basic dyes - correct answer -have a POSITIVE charge and bind to negatively charged molecules, such as
nucleic acids or bacterial surfaces
3 basic dyes - correct answer --methylene blue
-crystal violet
-safranin
Acidic dyes - correct answer -have a negative charge that binds to positively charged molecules, such as
tissue
2 acidic dyes - correct answer -eosin and nigrosin
