GCU MICROBIOLOGY FINAL EXAM REVIEW 2025
WITH 100% ACCURATE SOLUTIONS
Selective medium - Precise Answer ✔✔allow certain types of
organisms to grow, and inhibit the growth of other organisms
Differential medium - Precise Answer ✔✔medium permitting
certain organisms to be distinguished from others by the
appearance of their colonies
MacConkey agar selects for which group of bacteria? - Precise
Answer ✔✔not only selects for Gram-negative organisms by
inhibiting Gram-positive organisms and yeast but also
differentiates the Gram-negative organisms by lactose
fermentation
MacConkey agar media differentiates between enteric bacteria
based on what biochemical reaction? - Precise Answer
✔✔Based on lactose fermentation. The media starts red and will
turn yellow if the bacteria ferments.
,If the organism is E.coli, what would you see on your
MacConkey agar plates? - Precise Answer ✔✔E. coli will grow
due to being gram negative but will remain pink because it dose
not ferment lactose.
If the organism(s) is/are other enterics, what would you see on
your MacConkey agar plate? - Precise Answer ✔✔it would be
gram negative and the colonies would be yellow/orange and so
would the media.
EMB agar selects for which group of bacteria? - Precise Answer
✔✔Selects for Gram negative enteric bacteria.
EMB agar media differentiates between gram negative enteric
based on what biochemical reaction? - Precise Answer ✔✔is
based on lactose fermentation by eosin and methylene blue dye
If the organism is E.coli, what would you see on your EMB
plates? - Precise Answer ✔✔it would have dark blue-black
colonies with a green metallic sheen
, If the organism(s) is/are other enterics, what would you see on
your EMB plate? - Precise Answer ✔✔Gram-negative bacteria
that ferment the lactose produce acid which lowers the pH. This
encourages dye absorption by the colonies and turns the colonies
dark purple as the acid acts upon the dyes.
MSA agar selects for which group of bacteria? Explain. - Precise
Answer ✔✔is a selective medium used for the isolation of
pathogenic staphylococci.
MSA agar media differentiates staphylococcal species based on
what biochemical reaction? - Precise Answer ✔✔The high salt
concentration inhibits the growth of most bacteria other than
staphylococci.
If the organism is Staphylococcus aureus, what would you see
on your MSA plates? - Precise Answer ✔✔It grows on the plate
and turns it yellow
If the organism is other Staphylococcus epidermis, what would
you see on your MSA plate? - Precise Answer ✔✔It will not
grow and the media will remain pink
WITH 100% ACCURATE SOLUTIONS
Selective medium - Precise Answer ✔✔allow certain types of
organisms to grow, and inhibit the growth of other organisms
Differential medium - Precise Answer ✔✔medium permitting
certain organisms to be distinguished from others by the
appearance of their colonies
MacConkey agar selects for which group of bacteria? - Precise
Answer ✔✔not only selects for Gram-negative organisms by
inhibiting Gram-positive organisms and yeast but also
differentiates the Gram-negative organisms by lactose
fermentation
MacConkey agar media differentiates between enteric bacteria
based on what biochemical reaction? - Precise Answer
✔✔Based on lactose fermentation. The media starts red and will
turn yellow if the bacteria ferments.
,If the organism is E.coli, what would you see on your
MacConkey agar plates? - Precise Answer ✔✔E. coli will grow
due to being gram negative but will remain pink because it dose
not ferment lactose.
If the organism(s) is/are other enterics, what would you see on
your MacConkey agar plate? - Precise Answer ✔✔it would be
gram negative and the colonies would be yellow/orange and so
would the media.
EMB agar selects for which group of bacteria? - Precise Answer
✔✔Selects for Gram negative enteric bacteria.
EMB agar media differentiates between gram negative enteric
based on what biochemical reaction? - Precise Answer ✔✔is
based on lactose fermentation by eosin and methylene blue dye
If the organism is E.coli, what would you see on your EMB
plates? - Precise Answer ✔✔it would have dark blue-black
colonies with a green metallic sheen
, If the organism(s) is/are other enterics, what would you see on
your EMB plate? - Precise Answer ✔✔Gram-negative bacteria
that ferment the lactose produce acid which lowers the pH. This
encourages dye absorption by the colonies and turns the colonies
dark purple as the acid acts upon the dyes.
MSA agar selects for which group of bacteria? Explain. - Precise
Answer ✔✔is a selective medium used for the isolation of
pathogenic staphylococci.
MSA agar media differentiates staphylococcal species based on
what biochemical reaction? - Precise Answer ✔✔The high salt
concentration inhibits the growth of most bacteria other than
staphylococci.
If the organism is Staphylococcus aureus, what would you see
on your MSA plates? - Precise Answer ✔✔It grows on the plate
and turns it yellow
If the organism is other Staphylococcus epidermis, what would
you see on your MSA plate? - Precise Answer ✔✔It will not
grow and the media will remain pink
