Lab 9 and 10 microbiology Exam 2025
Questions and Answers
What type of medium is used to isolate Staphylococcus from the skin? - --
CORRECT ANSWER--Blood agar
What best describes hemolysis? - --CORRECT ANSWER--Rupturing of red blood
cells
What tool is used to isolate bacterial colonies in quadrant three and four of the
blood agar plate? - --CORRECT ANSWER--Inoculating loop flamed between
quadrants
What type of hemolysis is seen with most staphylococcal colonies? - --CORRECT
ANSWER--Gamma
What two microscopic characteristics indicate that the organism might be a
Staphylococcus? - --CORRECT ANSWER--Purple; spheres in clusters
What medium is used for preparation of stock cultures? - --CORRECT ANSWER-
-TSA slant
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, Which term best describes MSA medium? - --CORRECT ANSWER--Both
selective and differential
What indicates that a staphylococcus can ferment mannitol in MSA? - --
CORRECT ANSWER--It turns yellow due to a low pH
What do the clear zones indicate in an MSA medium? - --CORRECT ANSWER--
The presence of an enzyme
What do streptococci and staphylococci have in common? - --CORRECT
ANSWER--Both Gram positive
You have just isolated bacteria from the back of your throat. How can you most
quickly determine if you have streptococci or staphylococci? - --CORRECT
ANSWER--By a Catalase test
What indicates a positive catalase test? - --CORRECT ANSWER--Presence of
bubbles on the slide
Which of the following is a correct match? - --CORRECT ANSWER--
Staphylococcus--Catalase positive
What is the role of coagulase in an organism? - --CORRECT ANSWER--Clots
plasma
What is the expected result in a plasma tube if it is inoculated with coagulase-
positive staphylococci? - --CORRECT ANSWER--Plasma will not flow freely
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Questions and Answers
What type of medium is used to isolate Staphylococcus from the skin? - --
CORRECT ANSWER--Blood agar
What best describes hemolysis? - --CORRECT ANSWER--Rupturing of red blood
cells
What tool is used to isolate bacterial colonies in quadrant three and four of the
blood agar plate? - --CORRECT ANSWER--Inoculating loop flamed between
quadrants
What type of hemolysis is seen with most staphylococcal colonies? - --CORRECT
ANSWER--Gamma
What two microscopic characteristics indicate that the organism might be a
Staphylococcus? - --CORRECT ANSWER--Purple; spheres in clusters
What medium is used for preparation of stock cultures? - --CORRECT ANSWER-
-TSA slant
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 1
, Which term best describes MSA medium? - --CORRECT ANSWER--Both
selective and differential
What indicates that a staphylococcus can ferment mannitol in MSA? - --
CORRECT ANSWER--It turns yellow due to a low pH
What do the clear zones indicate in an MSA medium? - --CORRECT ANSWER--
The presence of an enzyme
What do streptococci and staphylococci have in common? - --CORRECT
ANSWER--Both Gram positive
You have just isolated bacteria from the back of your throat. How can you most
quickly determine if you have streptococci or staphylococci? - --CORRECT
ANSWER--By a Catalase test
What indicates a positive catalase test? - --CORRECT ANSWER--Presence of
bubbles on the slide
Which of the following is a correct match? - --CORRECT ANSWER--
Staphylococcus--Catalase positive
What is the role of coagulase in an organism? - --CORRECT ANSWER--Clots
plasma
What is the expected result in a plasma tube if it is inoculated with coagulase-
positive staphylococci? - --CORRECT ANSWER--Plasma will not flow freely
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 2
