MBIO 3401 EXAM 1 QUESTIONS AND ANSWERS 2026
Microbes include members of which of the following groups? - answers - bacteria,
archaea, fungi, viruses
Which of the following scientist-contribution pairs is not matched correctly? - answers -
louis pasteur proved spontaneous generation
What is robert kochs contribution - answers - developed the criteria for establishing a
causative link betwen an infectious agent and disease
What is leewunhoek's contribution - answers - discovered individual microbes
What is nightingales contributions - answers - founded medical statistics
Kochs postulates include all of the following except what - answers - the pathogen must
be shown to contain toxins
Kocks postulates - answers - a pure culture must be obtained, pathogne must be found
in every individual suffering from the disease, the isolated pathogen must be used to
infect healthy hosts, healthy individuals infected with osilated suspected pathogen must
get sick with disease
Who performed the first vaccination - answers - edward jenner
Who discovered the first antibiotic - answers - alexander fleming
Who are the ancestors of mitochondria - answers - proteobacteria
What size are normal microbes - answers - 10-100um
What type of microbes are less than 10um - answers - prokaryotes
What is the correct order of reagents in gram stain - answers - crystal violet, idodine,
ehtanol, safranin
In fluorescence micorscopy, the specimen absorbs incident light and then re-emits a
_____ energy and a _____ wavelength - answers - lower, longer
Which of the following microscopes allows the best view of bacterial flagella during
motility - answers - dark-field microscope
,What type pf microscopy exploits differnces in refactive indices between cell parts and
surroundign media as well as all live cells - answers - phase-contrst microscopy
Scanning electron microscopy - answers - specimen is fixed and embedded, it cannot
be used to view live specimen, provdes 3d image of the specimen
Atomic force microscope - answers - measures van der waals forces, example of
scanning probe microscop e
What is the best method to examining the presensce of a chemical structure with a
diameter of 3nm? - answers - x-ray crystallography
What is the structure of prokaryotes that performs the same function as mitochodria in
eukaryotes - answers - cell membrane
Lipids - answers - have ester linkages, while those of archaea have ether linkages
Component of peptidoglycan - answers - n-acetylmuramic acid, n-acetylglucosamine,
amino acids, peptide cross-links
Prokaryotic outer membrane - answers - found in gram negative bacteria, contains
porins, contains toxic component, contains lipopolysaccharide layer
Prokaryotic chromosome - answers - has a single origin of replication and then dna is
replicated bidirectionally
What does a stalked cell in caulobacter crescentus divide to reproduce - answers - a
stalked cell and a flagellated cell
What is an extension of the cytoplasm that attaches bacteria to a surface called -
answers - stalk
Prokaryotic flagella - answers - driven by proton motice force, found in both gram - and
gram +, embedded in the cell envelope, used for chemotaxis
Limitations for koch's postulates - answers - not all microbes can be grown in pure
culture, sometimes the causing agent can be found in both healthy and sick individuals,
not all those infected develop disease, not all pathogens have animal modes of infection
Causality of koch's postulates - answers - mycobacterium tuberculosis> tuberculosis,
bacillus antracis>anthrax
Association of koch's postulates - answers - men wear larger shoes and are stronger
than women. Do large shoes make you stronger?
, How does pasteur disprove spontaneous generation? - answers - the curve of the neck
prevented microbes from entering the broth. If the flask was broken, the broth would be
contaminated. Boiled broth to get rid of exsiting microbes
Why can microbes still grow after boiling? - answers - boiling will not kill endospores,
steam sterilization and autoclaving will completely sterilize the broth
What happens if crystal violet is not added? - answers - the iodine will not react with
anything and will be able to leave lipid bilayer after adding decolorizer. Once the counter
stain is added, both gram postive and negative will be red
What happens if iodine is not added during gram stain? - answers - crystal violet will not
react with anything and the decolorizer will be able to remove the cv. Both gram postive
and negative will be red after safrinin
What happens if decolorizer is not added during gram stain - answers - the negative
bacteria will retain the color of the cv, and both types of bacteria will be purple
What happens if the counter stain is not added when gram staining - answers - the
gram negative will be colorless after being decoloized. Gram negative will retain purple
color
What type of energy do photolithoautotrophs require - answers - sunlight through
photosynthesis
What type of energy do chemolithotrophs require - answers - inorganic molecule
How do you culture and isolate photolithoautotrophs - answers - incubate the culture
under sun light at room temp in a medium that does not contain organic carbon source
How do you culture and isolate a chemolithotrophs - answers - keep the culture in
darkness and provide inorganic carbon donors such as ammonium, sulfide, in the
medium. Do not provide organic carbon souce
Explain the results of direct count - answers - look at the number of microbes that are
both viable and non viable (all cells counted)
Explain the results of viable count - answers - the number of colonies that grow on
plates represent only the viable and replicative cells
Direct/viable ratio in the lag phase - answers - direct count>viable
Direct/viabel ratio of log phase - answers - direct=viable
Direct/viable ratio of stationary phase - answers - direct=viable (but as the phase
progresses there will be more direct count than viable)
Microbes include members of which of the following groups? - answers - bacteria,
archaea, fungi, viruses
Which of the following scientist-contribution pairs is not matched correctly? - answers -
louis pasteur proved spontaneous generation
What is robert kochs contribution - answers - developed the criteria for establishing a
causative link betwen an infectious agent and disease
What is leewunhoek's contribution - answers - discovered individual microbes
What is nightingales contributions - answers - founded medical statistics
Kochs postulates include all of the following except what - answers - the pathogen must
be shown to contain toxins
Kocks postulates - answers - a pure culture must be obtained, pathogne must be found
in every individual suffering from the disease, the isolated pathogen must be used to
infect healthy hosts, healthy individuals infected with osilated suspected pathogen must
get sick with disease
Who performed the first vaccination - answers - edward jenner
Who discovered the first antibiotic - answers - alexander fleming
Who are the ancestors of mitochondria - answers - proteobacteria
What size are normal microbes - answers - 10-100um
What type of microbes are less than 10um - answers - prokaryotes
What is the correct order of reagents in gram stain - answers - crystal violet, idodine,
ehtanol, safranin
In fluorescence micorscopy, the specimen absorbs incident light and then re-emits a
_____ energy and a _____ wavelength - answers - lower, longer
Which of the following microscopes allows the best view of bacterial flagella during
motility - answers - dark-field microscope
,What type pf microscopy exploits differnces in refactive indices between cell parts and
surroundign media as well as all live cells - answers - phase-contrst microscopy
Scanning electron microscopy - answers - specimen is fixed and embedded, it cannot
be used to view live specimen, provdes 3d image of the specimen
Atomic force microscope - answers - measures van der waals forces, example of
scanning probe microscop e
What is the best method to examining the presensce of a chemical structure with a
diameter of 3nm? - answers - x-ray crystallography
What is the structure of prokaryotes that performs the same function as mitochodria in
eukaryotes - answers - cell membrane
Lipids - answers - have ester linkages, while those of archaea have ether linkages
Component of peptidoglycan - answers - n-acetylmuramic acid, n-acetylglucosamine,
amino acids, peptide cross-links
Prokaryotic outer membrane - answers - found in gram negative bacteria, contains
porins, contains toxic component, contains lipopolysaccharide layer
Prokaryotic chromosome - answers - has a single origin of replication and then dna is
replicated bidirectionally
What does a stalked cell in caulobacter crescentus divide to reproduce - answers - a
stalked cell and a flagellated cell
What is an extension of the cytoplasm that attaches bacteria to a surface called -
answers - stalk
Prokaryotic flagella - answers - driven by proton motice force, found in both gram - and
gram +, embedded in the cell envelope, used for chemotaxis
Limitations for koch's postulates - answers - not all microbes can be grown in pure
culture, sometimes the causing agent can be found in both healthy and sick individuals,
not all those infected develop disease, not all pathogens have animal modes of infection
Causality of koch's postulates - answers - mycobacterium tuberculosis> tuberculosis,
bacillus antracis>anthrax
Association of koch's postulates - answers - men wear larger shoes and are stronger
than women. Do large shoes make you stronger?
, How does pasteur disprove spontaneous generation? - answers - the curve of the neck
prevented microbes from entering the broth. If the flask was broken, the broth would be
contaminated. Boiled broth to get rid of exsiting microbes
Why can microbes still grow after boiling? - answers - boiling will not kill endospores,
steam sterilization and autoclaving will completely sterilize the broth
What happens if crystal violet is not added? - answers - the iodine will not react with
anything and will be able to leave lipid bilayer after adding decolorizer. Once the counter
stain is added, both gram postive and negative will be red
What happens if iodine is not added during gram stain? - answers - crystal violet will not
react with anything and the decolorizer will be able to remove the cv. Both gram postive
and negative will be red after safrinin
What happens if decolorizer is not added during gram stain - answers - the negative
bacteria will retain the color of the cv, and both types of bacteria will be purple
What happens if the counter stain is not added when gram staining - answers - the
gram negative will be colorless after being decoloized. Gram negative will retain purple
color
What type of energy do photolithoautotrophs require - answers - sunlight through
photosynthesis
What type of energy do chemolithotrophs require - answers - inorganic molecule
How do you culture and isolate photolithoautotrophs - answers - incubate the culture
under sun light at room temp in a medium that does not contain organic carbon source
How do you culture and isolate a chemolithotrophs - answers - keep the culture in
darkness and provide inorganic carbon donors such as ammonium, sulfide, in the
medium. Do not provide organic carbon souce
Explain the results of direct count - answers - look at the number of microbes that are
both viable and non viable (all cells counted)
Explain the results of viable count - answers - the number of colonies that grow on
plates represent only the viable and replicative cells
Direct/viable ratio in the lag phase - answers - direct count>viable
Direct/viabel ratio of log phase - answers - direct=viable
Direct/viable ratio of stationary phase - answers - direct=viable (but as the phase
progresses there will be more direct count than viable)
