MIBO 3500 FINAL EXAM QUESTIONS & ANSWERS
millimeter (mm) - Answers -10^-3
micrometer (um) - Answers -10^-6
nanometer - Answers -10^-9
Microbes - Answers
-Organisms and acellular agents too small to be seen by the unaided eye
Robert Hooke - Answers -made first compound microscope, coined the term "cell"
Antoine van Leeuwenhoek - Answers -built single-lens magnifier, first to observe
single-felled microbes
Francesco Redi - Answers -meat and maggots research, disproved theory that
microbes spontaneously generated
Lazzaro Spallanzani - Answers -also disproved the spontaneous generation theory,
used broth covered and uncovered
Louis Pasteur - Answers -proposed the germ theory of disease, idea that the
transmission of microbes is what causes disease, also used Swan neck flasks and broth
to disprove spontaneous generation
germ theory of disease - Answers -idea that infectious diseases are caused by
microorganisms, important features: transmission, pure culture, colonies
Robert Koch - Answers -Father of microbiology, four postulates to establish link
between specific microbe and a disease
Koch's first postulate - Answers -Microorganism must be present in every case of the
disease and absent from healthy organisms
,Koch's Second Postulate - Answers -Microbe must be isolated and grown in pure
culture
Koch's Third Postulate - Answers -Same disease must result when organism is
inoculated in healthy host
Koch's Fourth Postulate - Answers -Same microorganism must be isolated from 2nd
diseases host
Limitations of Koch's Postulates - Answers -Some have immunity, some illnesses have
multiple causes/strains, and, since you can't inoculate humans, a disease that only
affects humans would be difficult to test
Lady Montagu - Answers -Introduces smallpox inoculation in 1717
Edward Jenner - Answers -Smallpox vaccine (furthers Lady Montagu's work)
Florence Nightingale - Answers -Used medical statistics to demonstrate the
significance of mortality due to disease during the Crimean War
Alexander Fleming - Answers -discovered penicillin
Howard Florey and Ernst Chain - Answers -Purified penicillin
Sergei Winogradsky - Answers -Discovered lithotrophs, developed enrichment cultures,
and built the Winogradsky column
Detection - Answers -The ability to determine the presence of an object
Magnification - Answers -An increase in the apparent size of an image
Resolution - Answers -Ability of a microscope to distinguish two objects as separate
light microscope - Answers --bright-field
-dark field
-phase contrast
-fluorescence
compound microscope - Answers -A light microscope that has more than one lens
bright-field microscopy - Answers -Ocular lens (10x), condenser, objective lens, total
magnification is equal to the product of the ocular lens magnification times the objective
lens, can see microbes but can't tell much about sample
,Limitations of bright-field microscopy - Answers --0.2 um between objects is best a
bright-field microscope can resolve
-staining can kill cells
-refraction reduces resolving power (immersion oil as a remedy)
-LITTLE DIFFERENCE IN COLOR INTENSITY BETWEEN SAMPLE AND
BACKGROUND for low contrast
dark-field microscopy - Answers -Microbes visualized as halos of bright light against
darkness
Allows detection of narrow cells (.1 um) unresolved in bright-field with a good
contrasting image
Limitations of dark-field microscopy - Answers --dust particles can be mistaken as
objects
-light shines at an oblique angle
-only light scattered by sample reaches objective
phase-contrast microscopy - Answers -Allows refractive differences in cell components
to be transformed into differences in light intensity (allows you to see internal
components)
Fluorescence microscopy - Answers -For specimens with added dye or naturally
photosynthetic microbes
Fluorophores - Answers -Chemical compounds that absorb/emit light of specific
wavelengths; can be a dye or protein
Fixation - Answers -Heat and chemicals retain morphology but inactivate enzymes
basic dyes - Answers -Positively charged
- examples: methylene blue, crystal violet, and safranin
- often used in the surface of a cell
RED after staining
acidic dyes - Answers -Negatively charged
- examples: eosin, rose bengal
- used on positively charged samples
BLUE after staining
simple staining - Answers -color added to specimen
Differential staining - Answers -gram staining, acid-fast staining, endosphere staining
Gram staining - Answers -Has to do with cell wall properties
, Peptidoglycan - Answers -Rigid structure that lies just outside the plasma membrane
(gram + has a lot, gram - has little)
Gram stain procedure - Answers -1. Add crystal violet after fixation (colorless)
2. Both are purple
3. Add iodine (traps crystal violet); still purple
4. Add alcohol (decolorizing step), which removes crystal violet only in gram -
5. Add counterstain, safranin
(Gram + will be purple, Gram - will be red)
If you forget to add the decolorizing agent when performing a Gram stain, what color will
the gram cells be? - Answers -Both will be purple
If you add too much decolorizing agent when performing a Gram stain, what color will
the gram cells be? - Answers -Both will be red
electron microscopy - Answers -Electrons used instead of light beam (shorter
wavelength means greater resolution)
Scanning Electron Microscopy - Answers
-Used to see external features
Transmission Electron Microscopy - Answers
millimeter (mm) - Answers -10^-3
micrometer (um) - Answers -10^-6
nanometer - Answers -10^-9
Microbes - Answers
-Organisms and acellular agents too small to be seen by the unaided eye
Robert Hooke - Answers -made first compound microscope, coined the term "cell"
Antoine van Leeuwenhoek - Answers -built single-lens magnifier, first to observe
single-felled microbes
Francesco Redi - Answers -meat and maggots research, disproved theory that
microbes spontaneously generated
Lazzaro Spallanzani - Answers -also disproved the spontaneous generation theory,
used broth covered and uncovered
Louis Pasteur - Answers -proposed the germ theory of disease, idea that the
transmission of microbes is what causes disease, also used Swan neck flasks and broth
to disprove spontaneous generation
germ theory of disease - Answers -idea that infectious diseases are caused by
microorganisms, important features: transmission, pure culture, colonies
Robert Koch - Answers -Father of microbiology, four postulates to establish link
between specific microbe and a disease
Koch's first postulate - Answers -Microorganism must be present in every case of the
disease and absent from healthy organisms
,Koch's Second Postulate - Answers -Microbe must be isolated and grown in pure
culture
Koch's Third Postulate - Answers -Same disease must result when organism is
inoculated in healthy host
Koch's Fourth Postulate - Answers -Same microorganism must be isolated from 2nd
diseases host
Limitations of Koch's Postulates - Answers -Some have immunity, some illnesses have
multiple causes/strains, and, since you can't inoculate humans, a disease that only
affects humans would be difficult to test
Lady Montagu - Answers -Introduces smallpox inoculation in 1717
Edward Jenner - Answers -Smallpox vaccine (furthers Lady Montagu's work)
Florence Nightingale - Answers -Used medical statistics to demonstrate the
significance of mortality due to disease during the Crimean War
Alexander Fleming - Answers -discovered penicillin
Howard Florey and Ernst Chain - Answers -Purified penicillin
Sergei Winogradsky - Answers -Discovered lithotrophs, developed enrichment cultures,
and built the Winogradsky column
Detection - Answers -The ability to determine the presence of an object
Magnification - Answers -An increase in the apparent size of an image
Resolution - Answers -Ability of a microscope to distinguish two objects as separate
light microscope - Answers --bright-field
-dark field
-phase contrast
-fluorescence
compound microscope - Answers -A light microscope that has more than one lens
bright-field microscopy - Answers -Ocular lens (10x), condenser, objective lens, total
magnification is equal to the product of the ocular lens magnification times the objective
lens, can see microbes but can't tell much about sample
,Limitations of bright-field microscopy - Answers --0.2 um between objects is best a
bright-field microscope can resolve
-staining can kill cells
-refraction reduces resolving power (immersion oil as a remedy)
-LITTLE DIFFERENCE IN COLOR INTENSITY BETWEEN SAMPLE AND
BACKGROUND for low contrast
dark-field microscopy - Answers -Microbes visualized as halos of bright light against
darkness
Allows detection of narrow cells (.1 um) unresolved in bright-field with a good
contrasting image
Limitations of dark-field microscopy - Answers --dust particles can be mistaken as
objects
-light shines at an oblique angle
-only light scattered by sample reaches objective
phase-contrast microscopy - Answers -Allows refractive differences in cell components
to be transformed into differences in light intensity (allows you to see internal
components)
Fluorescence microscopy - Answers -For specimens with added dye or naturally
photosynthetic microbes
Fluorophores - Answers -Chemical compounds that absorb/emit light of specific
wavelengths; can be a dye or protein
Fixation - Answers -Heat and chemicals retain morphology but inactivate enzymes
basic dyes - Answers -Positively charged
- examples: methylene blue, crystal violet, and safranin
- often used in the surface of a cell
RED after staining
acidic dyes - Answers -Negatively charged
- examples: eosin, rose bengal
- used on positively charged samples
BLUE after staining
simple staining - Answers -color added to specimen
Differential staining - Answers -gram staining, acid-fast staining, endosphere staining
Gram staining - Answers -Has to do with cell wall properties
, Peptidoglycan - Answers -Rigid structure that lies just outside the plasma membrane
(gram + has a lot, gram - has little)
Gram stain procedure - Answers -1. Add crystal violet after fixation (colorless)
2. Both are purple
3. Add iodine (traps crystal violet); still purple
4. Add alcohol (decolorizing step), which removes crystal violet only in gram -
5. Add counterstain, safranin
(Gram + will be purple, Gram - will be red)
If you forget to add the decolorizing agent when performing a Gram stain, what color will
the gram cells be? - Answers -Both will be purple
If you add too much decolorizing agent when performing a Gram stain, what color will
the gram cells be? - Answers -Both will be red
electron microscopy - Answers -Electrons used instead of light beam (shorter
wavelength means greater resolution)
Scanning Electron Microscopy - Answers
-Used to see external features
Transmission Electron Microscopy - Answers
