PORTAGE LEARNING MICROBIOLOGY
MODULE 4 2026/2027 ACTUAL
QUESTIONS WITH VERIFIED ANSWERS.
Growth Media
Liquid or solid formulated to support microbial growth. Contains
essential nutrients to provide the microbe with a source of
carbon/energy.
What is the nutrient composition of growth media?
The nutrient composition often includes a rich source of sugars,
amino acids, and vitamins.
Nutrient broth
Another name for growth media; used to grow microbes in
suspension
LB media
Lysongeny broth; perhaps the most common nutrient broth is
nutrient rich and is known for its ability to grow a vast array of
microbes
Selective conditions
An instance where a researcher wants to establish conditions
where various types of bacteria will grow, while others will not.
Differential conditions
An instance when a researcher wants to establish conditions
where several types of microbes can be grown simultaneously
while being able to distinguish one type from another.
Selective Media
, Allows for only the growth of certain microbes and, by
extension, restricts the growth of all others.
How is selective media accomplished?
(1) Limiting the amount of nutrients; (2) varying degrees of pH;
(3) various chemical additives that limit unwanted microbial
growth (ex: antibiotics).
Differential Media
Distinguishes between two, often related, microbes.
What is an example of differential media usage?
Both E. coli and Salmonella are Gram-negative, but can be
distinguished by the presence or absence of lactose
fermentation. If grown on the same differential media, E. coli
ferments and turns the culture red, while Salmonella does not
and will remain white/tan.
What is the use of selective media?
It inhibits growth of certain microbes while permitting growth of
others.
How does selective media work?
The media contains substances to promote or inhibit growth.
What are examples of selective media?
Antibiotics, sodium chloride, or bile salts
When using selective media, what is on the plate?
Only organisms that can survive on the media.
What is the use of differential media and plates?
It distinguishes between strains or species growing on the
same plate.
MODULE 4 2026/2027 ACTUAL
QUESTIONS WITH VERIFIED ANSWERS.
Growth Media
Liquid or solid formulated to support microbial growth. Contains
essential nutrients to provide the microbe with a source of
carbon/energy.
What is the nutrient composition of growth media?
The nutrient composition often includes a rich source of sugars,
amino acids, and vitamins.
Nutrient broth
Another name for growth media; used to grow microbes in
suspension
LB media
Lysongeny broth; perhaps the most common nutrient broth is
nutrient rich and is known for its ability to grow a vast array of
microbes
Selective conditions
An instance where a researcher wants to establish conditions
where various types of bacteria will grow, while others will not.
Differential conditions
An instance when a researcher wants to establish conditions
where several types of microbes can be grown simultaneously
while being able to distinguish one type from another.
Selective Media
, Allows for only the growth of certain microbes and, by
extension, restricts the growth of all others.
How is selective media accomplished?
(1) Limiting the amount of nutrients; (2) varying degrees of pH;
(3) various chemical additives that limit unwanted microbial
growth (ex: antibiotics).
Differential Media
Distinguishes between two, often related, microbes.
What is an example of differential media usage?
Both E. coli and Salmonella are Gram-negative, but can be
distinguished by the presence or absence of lactose
fermentation. If grown on the same differential media, E. coli
ferments and turns the culture red, while Salmonella does not
and will remain white/tan.
What is the use of selective media?
It inhibits growth of certain microbes while permitting growth of
others.
How does selective media work?
The media contains substances to promote or inhibit growth.
What are examples of selective media?
Antibiotics, sodium chloride, or bile salts
When using selective media, what is on the plate?
Only organisms that can survive on the media.
What is the use of differential media and plates?
It distinguishes between strains or species growing on the
same plate.
