Portage Learning BIOD 171Lab 9 Microbiology Lect
ure Midterm Exam 2 Questions and Answers
Using the observations made and recorded from PL09 Unknown
Pathogen, complete theresults sections accordingly.
1. Given Culture A and Culture B were accidentally mixed, what
observations were made from theGram stain (shown below)?
Gram-positive cocci (spherical) clusters and Gram-negative bacillus
(rods) were observed.
2. Given the results from a MacConkey agar plate shown below, what
is the shape of Culture A?Culture B?
MacConkey agar is selective for Gram-negative bacteria. Thus,
Culture A must be Gram-positive as no growth was observed.
Coupled to the results of the gram stain, Culture A(Gram-positive)
must be the cocci.
, Culture B must be Gram-negative (growth observed) and this
correlates to the bacillus orrod-shaped bacteria.
3. The hemolytic properties of both cultures were next examined by
streaking each culture on ablood agar plate (shown below). What is
the hemolytic status of Culture A? Culture B?
Culture A exhibits beta hemolysis as defined by the region of clearing
around the growingbacterial streak.
Culture B exhibits gamma-hemolysis (non-hemolytic) as indicated
by the white coloniesgrowing on the still red agar.
ure Midterm Exam 2 Questions and Answers
Using the observations made and recorded from PL09 Unknown
Pathogen, complete theresults sections accordingly.
1. Given Culture A and Culture B were accidentally mixed, what
observations were made from theGram stain (shown below)?
Gram-positive cocci (spherical) clusters and Gram-negative bacillus
(rods) were observed.
2. Given the results from a MacConkey agar plate shown below, what
is the shape of Culture A?Culture B?
MacConkey agar is selective for Gram-negative bacteria. Thus,
Culture A must be Gram-positive as no growth was observed.
Coupled to the results of the gram stain, Culture A(Gram-positive)
must be the cocci.
, Culture B must be Gram-negative (growth observed) and this
correlates to the bacillus orrod-shaped bacteria.
3. The hemolytic properties of both cultures were next examined by
streaking each culture on ablood agar plate (shown below). What is
the hemolytic status of Culture A? Culture B?
Culture A exhibits beta hemolysis as defined by the region of clearing
around the growingbacterial streak.
Culture B exhibits gamma-hemolysis (non-hemolytic) as indicated
by the white coloniesgrowing on the still red agar.
