Microbiology Lab Exam 1 with Complete
Solutions
What is the purpose of a streak plate? Correct Ans-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? Correct Ans-Areas of growth that arise from a single cell.
How do colonies form? Correct Ans-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? Correct Ans-Culture containing only one type of organism
What kind of media are colonies able to form on? Correct Ans-agar slant, broth media, agar
plate
When is a agar slant used? Pros & cons Correct Ans-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
What are the 4 criteria for labeling a microbial culture? Correct Ans-1) initials or name AND
group number
2) date
,3) growth media type
4) culture name or source of inoculum
Describe bacillus (bacilli) morphology Correct Ans-rod shaped cells, longer than wide,
sausage like, can use rod or bacillus
describe coccus morphology Correct Ans-cells are ball shaped or spherical
Describe coccobacillus morphology Correct Ans-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 Correct Ans-Helical, loose or tight coils. Look like wavy
lines - morphology has no arrangement
Describe filamentous morphology Correct Ans-Long elongated cells. Look like a tangled
mass of branched filaments- no arrangement
Describe vibrio morphology Correct Ans-A curved rod or comma shape
What does No arrangement mean? Correct Ans-Single cells, ungrouped. Not all cells have an
arrangement
, What is the cell arrangement Diplococci/Diplobacilli Correct Ans-Pairs of cells. Diplococci
are pairs of cocci, diplobacilli are pairs of rods
What is the cell arrangement Streptococci/Streptobacilli? Correct Ans-Chains of cells.
Streptococci are chains of cocci, streptobacilli are chains of rods
What is the call arrangement staphylococcus? Correct Ans-Irregular clusters of cells- like
bunches of grapes.
What is the cell arrangement of tetrads? Correct Ans-Sets of 4 regularly arranged cells
What is the cell arrangement of palisade? Correct Ans-Bacilli (usually 2-4 cells) arranged
side by side. Columns or "V-forms"
What genus is an acid fast bacteria? Correct Ans-Mycobacterium tuberculosis
What genus is an capsule former? Correct Ans-Klebsiella pneumoniae
What is a simple stain? Correct Ans-Involves only one dye to make cells more visable.
Involves methylene blue or crystal voilet.
What is a complex stain? Correct Ans-Two or more stains. Allow the differentiation of cell
types or cell structures. (can be called differential stain)
Solutions
What is the purpose of a streak plate? Correct Ans-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? Correct Ans-Areas of growth that arise from a single cell.
How do colonies form? Correct Ans-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? Correct Ans-Culture containing only one type of organism
What kind of media are colonies able to form on? Correct Ans-agar slant, broth media, agar
plate
When is a agar slant used? Pros & cons Correct Ans-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
What are the 4 criteria for labeling a microbial culture? Correct Ans-1) initials or name AND
group number
2) date
,3) growth media type
4) culture name or source of inoculum
Describe bacillus (bacilli) morphology Correct Ans-rod shaped cells, longer than wide,
sausage like, can use rod or bacillus
describe coccus morphology Correct Ans-cells are ball shaped or spherical
Describe coccobacillus morphology Correct Ans-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 Correct Ans-Helical, loose or tight coils. Look like wavy
lines - morphology has no arrangement
Describe filamentous morphology Correct Ans-Long elongated cells. Look like a tangled
mass of branched filaments- no arrangement
Describe vibrio morphology Correct Ans-A curved rod or comma shape
What does No arrangement mean? Correct Ans-Single cells, ungrouped. Not all cells have an
arrangement
, What is the cell arrangement Diplococci/Diplobacilli Correct Ans-Pairs of cells. Diplococci
are pairs of cocci, diplobacilli are pairs of rods
What is the cell arrangement Streptococci/Streptobacilli? Correct Ans-Chains of cells.
Streptococci are chains of cocci, streptobacilli are chains of rods
What is the call arrangement staphylococcus? Correct Ans-Irregular clusters of cells- like
bunches of grapes.
What is the cell arrangement of tetrads? Correct Ans-Sets of 4 regularly arranged cells
What is the cell arrangement of palisade? Correct Ans-Bacilli (usually 2-4 cells) arranged
side by side. Columns or "V-forms"
What genus is an acid fast bacteria? Correct Ans-Mycobacterium tuberculosis
What genus is an capsule former? Correct Ans-Klebsiella pneumoniae
What is a simple stain? Correct Ans-Involves only one dye to make cells more visable.
Involves methylene blue or crystal voilet.
What is a complex stain? Correct Ans-Two or more stains. Allow the differentiation of cell
types or cell structures. (can be called differential stain)
