Portage Learning: Microbiology Module 4 Questions and
Answers
Question 1
What is another name for a liquid growth media, and what are the basic components?
Correct Answer
Growth media in a liquid form is often referred to as nutrient broth. As the name implies its composition consists
primarily of essential 'ingredients' such as a rich source of sugars, amino acids and vitamins. Together, a nutrient broth
provides the microbe with a source of carbon/energy, which, in turn, encourages its expansion.
Question 2
What is selective media?
Correct Answer
Selective media allows for only the growth of certain microbes while restricting the growth of all others.
Question 3
What is differential media?
Correct Answer
Differential media is used to distinguish between two (or more) related microbes.
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, Question 4
What are the requirements of a fastidious microbe?
Correct Answer
A fastidious microbe is an organism with complex growth requirements such that if absent it will not grow. Enriched
medias thus contain these specific and essential nutrients required for the growth of a particular subset of
microorganisms.
Question 5
What is agar?
Correct Answer
In its simplest form agar is liquid growth media that has had a hardening agent added to it. Agar is created when a
polysaccharide derived from seaweed (algae) extract is added to growth media. Agar is used to create a solid, smooth
surface on which microbes can grow.
Question 6
True or False: LB agar is classified as a non-selective, differential media.
Correct Answer
False. LB agar is both a non-selective and non-differential media. LB agar is often used to expand unknown microbial
population because it encourages microbial growth due to the presence of universal nutrients (non-differential) and
absence of restrictive factors (non-selective).
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Answers
Question 1
What is another name for a liquid growth media, and what are the basic components?
Correct Answer
Growth media in a liquid form is often referred to as nutrient broth. As the name implies its composition consists
primarily of essential 'ingredients' such as a rich source of sugars, amino acids and vitamins. Together, a nutrient broth
provides the microbe with a source of carbon/energy, which, in turn, encourages its expansion.
Question 2
What is selective media?
Correct Answer
Selective media allows for only the growth of certain microbes while restricting the growth of all others.
Question 3
What is differential media?
Correct Answer
Differential media is used to distinguish between two (or more) related microbes.
Page 1 of 5
, Question 4
What are the requirements of a fastidious microbe?
Correct Answer
A fastidious microbe is an organism with complex growth requirements such that if absent it will not grow. Enriched
medias thus contain these specific and essential nutrients required for the growth of a particular subset of
microorganisms.
Question 5
What is agar?
Correct Answer
In its simplest form agar is liquid growth media that has had a hardening agent added to it. Agar is created when a
polysaccharide derived from seaweed (algae) extract is added to growth media. Agar is used to create a solid, smooth
surface on which microbes can grow.
Question 6
True or False: LB agar is classified as a non-selective, differential media.
Correct Answer
False. LB agar is both a non-selective and non-differential media. LB agar is often used to expand unknown microbial
population because it encourages microbial growth due to the presence of universal nutrients (non-differential) and
absence of restrictive factors (non-selective).
Page 2 of 5
