MBIO 3401 Exam 1 Zhang LATEST VERSION 2025/2026 QUESTIONS
AND CORRECT DETAILED ANSWERS (VERIFIED ANSWERS) |ALREADY
GRADED A
microbes include members of which of the following groups? - correct answer bacteria,
archaea, fungi, viruses
which of the following scientist-contribution pairs is not matched correctly? - correct answer
louis pasteur proved spontaneous generation
what is robert kochs contribution - correct answer developed the criteria for establishing a
causative link betwen an infectious agent and disease
what is leewunhoek's contribution - correct answer discovered individual microbes
what is nightingales contributions - correct answer founded medical statistics
kochs postulates include all of the following except what - correct answer the pathogen must
be shown to contain toxins
kocks postulates - correct answer 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 - correct answer edward jenner
who discovered the first antibiotic - correct answer alexander fleming
who are the ancestors of mitochondria - correct answer proteobacteria
what size are normal microbes - correct answer <0.2mm, <200um
what type of microbes are less than 10um - correct answer prokaryotes
what is the correct order of reagents in gram stain - correct answer crystal violet, idodine,
ehtanol, safranin
in fluorescence micorscopy, the specimen absorbs incident light and then re-emits a _____
energy and a _____ wavelength - correct answer lower, longer
which of the following microscopes allows the best view of bacterial flagella during motility -
correct answer dark-field microscope
what type pf microscopy exploits differnces in refactive indices between cell parts and
surroundign media as well as all live cells - correct answer phase-contrst microscopy
,scanning electron microscopy - correct answer specimen is fixed and embedded, it cannot be
used to view live specimen, provdes 3D image of the specimen
atomic force microscope - correct answer 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? - correct answer x-ray crystallography
what is the structure of prokaryotes that performs the same function as mitochodria in
eukaryotes - correct answer cell membrane
lipids - correct answer have ester linkages, while those of archaea have ether linkages
component of peptidoglycan - correct answer n-acetylmuramic acid, n-acetylglucosamine,
amino acids, peptide cross-links
prokaryotic outer membrane - correct answer found in gram negative bacteria, contains porins,
contains toxic component, contains lipopolysaccharide layer
prokaryotic chromosome - correct answer has a single origin of replication and then DNA is
replicated bidirectionally
what does a stalked cell in caulobacter crescentus divide to reproduce - correct answer a
stalked cell and a flagellated cell
what is an extension of the cytoplasm that attaches bacteria to a surface called - correct answer
stalk
prokaryotic flagella - correct answer driven by proton motice force, found in both gram - and
gram +, embedded in the cell envelope, used for chemotaxis
limitations for koch's postulates - correct answer 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 - correct answer mycobacterium tuberculosis> tuberculosis,
bacillus antracis>anthrax
association of koch's postulates - correct answer men wear larger shoes and are stronger than
women. do large shoes make you stronger?
how does pasteur disprove spontaneous generation? - correct answer 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? - correct answer boiling will not kill endospores,
steam sterilization and autoclaving will completely sterilize the broth
, what happens if crystal violet is not added? - correct answer 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? - correct answer 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 - correct answer 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 - correct answer the gram
negative will be colorless after being decoloized. gram negative will retain purple color
what type of energy do photolithoautotrophs require - correct answer sunlight through
photosynthesis
what type of energy do chemolithotrophs require - correct answer inorganic molecule
how do you culture and isolate photolithoautotrophs - correct answer 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 - correct answer 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 - correct answer look at the number of microbes that are
both viable and non viable (all cells counted)
explain the results of viable count - correct answer the number of colonies that grow on plates
represent only the viable and replicative cells
direct/viable ratio in the lag phase - correct answer direct count>viable
direct/viabel ratio of log phase - correct answer direct=viable
direct/viable ratio of stationary phase - correct answer direct=viable (but as the phase
progresses there will be more direct count than viable)
direct/viable ration of death phase - correct answer direct>viable
list advantages of phage therapy - correct answer potent on drug resistant/sensitive bacteria,
low toxicity (only infect specific type of bacteria), low cost of use, effective against planktonic
and biofilms
what is phage therapy - correct answer use of bacteriophage to treat patogenic bacterial
infections
AND CORRECT DETAILED ANSWERS (VERIFIED ANSWERS) |ALREADY
GRADED A
microbes include members of which of the following groups? - correct answer bacteria,
archaea, fungi, viruses
which of the following scientist-contribution pairs is not matched correctly? - correct answer
louis pasteur proved spontaneous generation
what is robert kochs contribution - correct answer developed the criteria for establishing a
causative link betwen an infectious agent and disease
what is leewunhoek's contribution - correct answer discovered individual microbes
what is nightingales contributions - correct answer founded medical statistics
kochs postulates include all of the following except what - correct answer the pathogen must
be shown to contain toxins
kocks postulates - correct answer 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 - correct answer edward jenner
who discovered the first antibiotic - correct answer alexander fleming
who are the ancestors of mitochondria - correct answer proteobacteria
what size are normal microbes - correct answer <0.2mm, <200um
what type of microbes are less than 10um - correct answer prokaryotes
what is the correct order of reagents in gram stain - correct answer crystal violet, idodine,
ehtanol, safranin
in fluorescence micorscopy, the specimen absorbs incident light and then re-emits a _____
energy and a _____ wavelength - correct answer lower, longer
which of the following microscopes allows the best view of bacterial flagella during motility -
correct answer dark-field microscope
what type pf microscopy exploits differnces in refactive indices between cell parts and
surroundign media as well as all live cells - correct answer phase-contrst microscopy
,scanning electron microscopy - correct answer specimen is fixed and embedded, it cannot be
used to view live specimen, provdes 3D image of the specimen
atomic force microscope - correct answer 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? - correct answer x-ray crystallography
what is the structure of prokaryotes that performs the same function as mitochodria in
eukaryotes - correct answer cell membrane
lipids - correct answer have ester linkages, while those of archaea have ether linkages
component of peptidoglycan - correct answer n-acetylmuramic acid, n-acetylglucosamine,
amino acids, peptide cross-links
prokaryotic outer membrane - correct answer found in gram negative bacteria, contains porins,
contains toxic component, contains lipopolysaccharide layer
prokaryotic chromosome - correct answer has a single origin of replication and then DNA is
replicated bidirectionally
what does a stalked cell in caulobacter crescentus divide to reproduce - correct answer a
stalked cell and a flagellated cell
what is an extension of the cytoplasm that attaches bacteria to a surface called - correct answer
stalk
prokaryotic flagella - correct answer driven by proton motice force, found in both gram - and
gram +, embedded in the cell envelope, used for chemotaxis
limitations for koch's postulates - correct answer 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 - correct answer mycobacterium tuberculosis> tuberculosis,
bacillus antracis>anthrax
association of koch's postulates - correct answer men wear larger shoes and are stronger than
women. do large shoes make you stronger?
how does pasteur disprove spontaneous generation? - correct answer 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? - correct answer boiling will not kill endospores,
steam sterilization and autoclaving will completely sterilize the broth
, what happens if crystal violet is not added? - correct answer 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? - correct answer 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 - correct answer 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 - correct answer the gram
negative will be colorless after being decoloized. gram negative will retain purple color
what type of energy do photolithoautotrophs require - correct answer sunlight through
photosynthesis
what type of energy do chemolithotrophs require - correct answer inorganic molecule
how do you culture and isolate photolithoautotrophs - correct answer 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 - correct answer 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 - correct answer look at the number of microbes that are
both viable and non viable (all cells counted)
explain the results of viable count - correct answer the number of colonies that grow on plates
represent only the viable and replicative cells
direct/viable ratio in the lag phase - correct answer direct count>viable
direct/viabel ratio of log phase - correct answer direct=viable
direct/viable ratio of stationary phase - correct answer direct=viable (but as the phase
progresses there will be more direct count than viable)
direct/viable ration of death phase - correct answer direct>viable
list advantages of phage therapy - correct answer potent on drug resistant/sensitive bacteria,
low toxicity (only infect specific type of bacteria), low cost of use, effective against planktonic
and biofilms
what is phage therapy - correct answer use of bacteriophage to treat patogenic bacterial
infections
