Microbiology Lab Exam 1 Questions
and Answers 100% Pass
What is the purpose of a streak plate? - ✔✔1) To separate cells so that they grow to form
isolated colonies 2) To confirm if a culture is a pure colony or mixed 3) To confirm is
there is contamination in your culture
What is a colony? - ✔✔Areas of growth that arise from a single cell.
How do colonies form? - ✔✔They are formed by spreading out cells. Cells are spread
and reproduce over and over again through bionary fission until visable mass of cells
appear.
What is a pure culture? - ✔✔Culture containing only one type of organism
What kind of media are colonies able to form on? - ✔✔agar slant, broth media, agar
plate
When is a agar slant used? Pros & cons - ✔✔1) Smaller amount of surface area prevents
the media from drying out too quickly 2) useful for medium term storage 3) viable for a
couple of months if stored properly
Katelyn Whitman, All Rights Reserved © 2025 1
,What are the 4 criteria for labeling a microbial culture? - ✔✔1) initials or name AND
group number
2) date
3) growth media type
4) culture name or source of inoculum
Describe bacillus (bacilli) morphology - ✔✔rod shaped cells, longer than wide, sausage
like, can use rod or bacillus
describe coccus morphology - ✔✔cells are ball shaped or spherical
Describe coccobacillus morphology - ✔✔elongated spheres- not quite spherical, but not
clearly a rod. Tends to occur in species which are normally rod-shaped during rapid
growth.
Describe spirillum morphology - ✔✔Helical, loose or tight coils. Look like wavy lines -
morphology has no arrangement
Describe filamentous morphology - ✔✔Long elongated cells. Look like a tangled mass
of branched filaments- no arrangement
Describe vibrio morphology - ✔✔A curved rod or comma shape
What does No arrangement mean? - ✔✔Single cells, ungrouped. Not all cells have an
arrangement
Katelyn Whitman, All Rights Reserved © 2025 2
, What is the cell arrangement Diplococci/Diplobacilli - ✔✔Pairs of cells. Diplococci are
pairs of cocci, diplobacilli are pairs of rods
What is the cell arrangement Streptococci/Streptobacilli? - ✔✔Chains of cells.
Streptococci are chains of cocci, streptobacilli are chains of rods
What is the call arrangement staphylococcus? - ✔✔Irregular clusters of cells- like
bunches of grapes.
What is the cell arrangement of tetrads? - ✔✔Sets of 4 regularly arranged cells
What is the cell arrangement of palisade? - ✔✔Bacilli (usually 2-4 cells) arranged side by
side. Columns or "V-forms"
What genus is an acid fast bacteria? - ✔✔Mycobacterium tuberculosis
What genus is an capsule former? - ✔✔Klebsiella pneumoniae
What is a simple stain? - ✔✔Involves only one dye to make cells more visable. Involves
methylene blue or crystal voilet.
What is a complex stain? - ✔✔Two or more stains. Allow the differentiation of cell types
or cell structures. (can be called differential stain)
What is a differential stain? - ✔✔Another name for complex stain. Allow us to see the
differences between different cell types or cell structures. Uses at least two different
stains.
Katelyn Whitman, All Rights Reserved © 2025 3
and Answers 100% Pass
What is the purpose of a streak plate? - ✔✔1) To separate cells so that they grow to form
isolated colonies 2) To confirm if a culture is a pure colony or mixed 3) To confirm is
there is contamination in your culture
What is a colony? - ✔✔Areas of growth that arise from a single cell.
How do colonies form? - ✔✔They are formed by spreading out cells. Cells are spread
and reproduce over and over again through bionary fission until visable mass of cells
appear.
What is a pure culture? - ✔✔Culture containing only one type of organism
What kind of media are colonies able to form on? - ✔✔agar slant, broth media, agar
plate
When is a agar slant used? Pros & cons - ✔✔1) Smaller amount of surface area prevents
the media from drying out too quickly 2) useful for medium term storage 3) viable for a
couple of months if stored properly
Katelyn Whitman, All Rights Reserved © 2025 1
,What are the 4 criteria for labeling a microbial culture? - ✔✔1) initials or name AND
group number
2) date
3) growth media type
4) culture name or source of inoculum
Describe bacillus (bacilli) morphology - ✔✔rod shaped cells, longer than wide, sausage
like, can use rod or bacillus
describe coccus morphology - ✔✔cells are ball shaped or spherical
Describe coccobacillus morphology - ✔✔elongated spheres- not quite spherical, but not
clearly a rod. Tends to occur in species which are normally rod-shaped during rapid
growth.
Describe spirillum morphology - ✔✔Helical, loose or tight coils. Look like wavy lines -
morphology has no arrangement
Describe filamentous morphology - ✔✔Long elongated cells. Look like a tangled mass
of branched filaments- no arrangement
Describe vibrio morphology - ✔✔A curved rod or comma shape
What does No arrangement mean? - ✔✔Single cells, ungrouped. Not all cells have an
arrangement
Katelyn Whitman, All Rights Reserved © 2025 2
, What is the cell arrangement Diplococci/Diplobacilli - ✔✔Pairs of cells. Diplococci are
pairs of cocci, diplobacilli are pairs of rods
What is the cell arrangement Streptococci/Streptobacilli? - ✔✔Chains of cells.
Streptococci are chains of cocci, streptobacilli are chains of rods
What is the call arrangement staphylococcus? - ✔✔Irregular clusters of cells- like
bunches of grapes.
What is the cell arrangement of tetrads? - ✔✔Sets of 4 regularly arranged cells
What is the cell arrangement of palisade? - ✔✔Bacilli (usually 2-4 cells) arranged side by
side. Columns or "V-forms"
What genus is an acid fast bacteria? - ✔✔Mycobacterium tuberculosis
What genus is an capsule former? - ✔✔Klebsiella pneumoniae
What is a simple stain? - ✔✔Involves only one dye to make cells more visable. Involves
methylene blue or crystal voilet.
What is a complex stain? - ✔✔Two or more stains. Allow the differentiation of cell types
or cell structures. (can be called differential stain)
What is a differential stain? - ✔✔Another name for complex stain. Allow us to see the
differences between different cell types or cell structures. Uses at least two different
stains.
Katelyn Whitman, All Rights Reserved © 2025 3
