MIBO 3500 FINAL EXAM QUESTIONS & ANSWERS
Microbial size definition - Answers -organisms and acellular agents too small to be
seen by the unaided eye
contradictions to this definition - Answers --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? - Answers -No, the mask protects against microbes that are 1-5
nanometers, and the tuberculosis particles are larger than 5 nanometers
Robert Hooke - Answers --built first compound microscope to observe mole and cork
-published Micrographia
-coined the term "cell"
Antoine van Leeuwenhoek - Answers --built single lens magnifiers
-first to observe single-celled microbes, called them "small animals"
Francesco Redi - Answers -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 - Answers -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 - Answers -disproved spontaneous generation using broth and bottle-
neck experiment
spontaneous generation - Answers -living organisms can arise from non-living matter
Germ theory - Answers -the theory that many diseases are caused by microbes (chain
of infection, pure culture, colonies)
Chain of infection - Answers -transmission of infectious microbes
Pure culture - Answers -culture from a single parental cell
,Colonies - Answers -distinct populations each grown from a single cell
Robert Koch - Answers -Developed first guidelines (postulates) to establish a link
between a specific microbe and disease
Koch's postulates (4) - Answers -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 - Answers -the first to use medical statistics to demonstrate the
significance of mortality due to disease
Alexander Fleming - Answers -discovered that Penicillium mold generated a substance
that can kill bacteria
Howard Florey and Ernst Chain - Answers -purified penicillin, first commercial antibiotic
to save lives
Sergei Winogradsky - Answers -among the first to study microbes in natural habitats,
discovered lithotrophis, and developed enrichment cultures. ALso build Winogradsky
column
Resolution - Answers -the ability to distinguish small objects close together
Magnification - Answers -enlarged image of an object
Contrast - Answers -the difference in color intensity between an object and its
background
4 types of light microscopes - Answers -bright-field
dark-field
phase-contrast
fluorescence
Compound microscope - Answers -a microscope that forms an image from more than
two lenses
Images produced by bright field microscopes are real or virtual? - Answers -virtual
Bright-field microscopy - Answers --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 - Answers -bending of light as it passes through an object that slows its
speed
Dark-field microscopy - Answers --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 - Answers -refractive differences in cell components are
transformed into differences in light intensity
Fluorescence microscopy - Answers -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 - Answers -chemical compounds that absorb/emit light of specific
wavelengths, can be a dye or a protein
Why do researchers stain microbes? - Answers --increases visibility
-preserves sample
-highlights morphological features
Heat fixation - Answers -uses flame to preserve internal and external morphology but
inactivates enzymes
Chemical fixation - Answers -uses ethanol, preseves morphology of microbe but may
also inactivate enzymes
basic dyes - Answers -have a POSITIVE charge and bind to negatively charged
molecules, such as nucleic acids or bacterial surfaces
3 basic dyes - Answers --methylene blue
-crystal violet
-safranin
Acidic dyes - Answers -have a negative charge that binds to positively charged
molecules, such as tissue
2 acidic dyes - Answers -eosin and nigrosin
simple stains - Answers -add color to the cells but not background
Differential staining definition and 3 types covered in class - Answers -stains one kind
of cell but not another
-gram
-acid fast
, -endospore
Gram staining - Answers -differential staining based on cell wall properties
Acid-fast staining - Answers -differential staining based on lipid content in cell walls
Endospore staining - Answers -differential staining based on vegetative and dormant
spores
Peptidoglycan - Answers -rigid structure that lies just outside of plasma membrane
Gram + bacteria have (thick/thin or no) peptidoglycan layers - Answers -thick
Gram stain procedure (long) - Answers -1) Add crystal violet, turning all bacteria purple.
2) Add iodine, which traps crystal violet in thick pep layers of gram + bacteria. All
bacteria is still purple.
3) Wash sample with alcohol, removing purple color from gram - bacteria; gram =
remains purple.
4) Add safranin, which does not affect gram + bacteria, but turns gram _ bacteria red
Electron microscopy - Answers -electrons are used instead of light beam. Beam
wavelength is extremely short, allowing great resolution.
Bacilli rods - Answers –
Paired cocci - Answers –
Microbial size definition - Answers -organisms and acellular agents too small to be
seen by the unaided eye
contradictions to this definition - Answers --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? - Answers -No, the mask protects against microbes that are 1-5
nanometers, and the tuberculosis particles are larger than 5 nanometers
Robert Hooke - Answers --built first compound microscope to observe mole and cork
-published Micrographia
-coined the term "cell"
Antoine van Leeuwenhoek - Answers --built single lens magnifiers
-first to observe single-celled microbes, called them "small animals"
Francesco Redi - Answers -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 - Answers -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 - Answers -disproved spontaneous generation using broth and bottle-
neck experiment
spontaneous generation - Answers -living organisms can arise from non-living matter
Germ theory - Answers -the theory that many diseases are caused by microbes (chain
of infection, pure culture, colonies)
Chain of infection - Answers -transmission of infectious microbes
Pure culture - Answers -culture from a single parental cell
,Colonies - Answers -distinct populations each grown from a single cell
Robert Koch - Answers -Developed first guidelines (postulates) to establish a link
between a specific microbe and disease
Koch's postulates (4) - Answers -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 - Answers -the first to use medical statistics to demonstrate the
significance of mortality due to disease
Alexander Fleming - Answers -discovered that Penicillium mold generated a substance
that can kill bacteria
Howard Florey and Ernst Chain - Answers -purified penicillin, first commercial antibiotic
to save lives
Sergei Winogradsky - Answers -among the first to study microbes in natural habitats,
discovered lithotrophis, and developed enrichment cultures. ALso build Winogradsky
column
Resolution - Answers -the ability to distinguish small objects close together
Magnification - Answers -enlarged image of an object
Contrast - Answers -the difference in color intensity between an object and its
background
4 types of light microscopes - Answers -bright-field
dark-field
phase-contrast
fluorescence
Compound microscope - Answers -a microscope that forms an image from more than
two lenses
Images produced by bright field microscopes are real or virtual? - Answers -virtual
Bright-field microscopy - Answers --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 - Answers -bending of light as it passes through an object that slows its
speed
Dark-field microscopy - Answers --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 - Answers -refractive differences in cell components are
transformed into differences in light intensity
Fluorescence microscopy - Answers -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 - Answers -chemical compounds that absorb/emit light of specific
wavelengths, can be a dye or a protein
Why do researchers stain microbes? - Answers --increases visibility
-preserves sample
-highlights morphological features
Heat fixation - Answers -uses flame to preserve internal and external morphology but
inactivates enzymes
Chemical fixation - Answers -uses ethanol, preseves morphology of microbe but may
also inactivate enzymes
basic dyes - Answers -have a POSITIVE charge and bind to negatively charged
molecules, such as nucleic acids or bacterial surfaces
3 basic dyes - Answers --methylene blue
-crystal violet
-safranin
Acidic dyes - Answers -have a negative charge that binds to positively charged
molecules, such as tissue
2 acidic dyes - Answers -eosin and nigrosin
simple stains - Answers -add color to the cells but not background
Differential staining definition and 3 types covered in class - Answers -stains one kind
of cell but not another
-gram
-acid fast
, -endospore
Gram staining - Answers -differential staining based on cell wall properties
Acid-fast staining - Answers -differential staining based on lipid content in cell walls
Endospore staining - Answers -differential staining based on vegetative and dormant
spores
Peptidoglycan - Answers -rigid structure that lies just outside of plasma membrane
Gram + bacteria have (thick/thin or no) peptidoglycan layers - Answers -thick
Gram stain procedure (long) - Answers -1) Add crystal violet, turning all bacteria purple.
2) Add iodine, which traps crystal violet in thick pep layers of gram + bacteria. All
bacteria is still purple.
3) Wash sample with alcohol, removing purple color from gram - bacteria; gram =
remains purple.
4) Add safranin, which does not affect gram + bacteria, but turns gram _ bacteria red
Electron microscopy - Answers -electrons are used instead of light beam. Beam
wavelength is extremely short, allowing great resolution.
Bacilli rods - Answers –
Paired cocci - Answers –
