D311: Microbiology with Lab: A Fundamental Approach Lesson
Quizzes
Section 2 – Microbial Environments
These are the questions for the lesson quizzes and section tests from the
course material. Please answer the questions, but also for each answer
choice, explain why the choice is correct or incorrect. For example, if the
answer is B, please explain why B is correct and why choices A, C, and D
are incorrect, for each question. This will give you extra practice with the
material, which will help with synthesis and retention.
Please watch the following videos to help you explain each answer choice
for Lesson 1.
The Rhizosphere
Section 2 Lesson 1 Quiz
1. What is a characteristic of rhizospheres?
a. The rhizosphere is where microbes that survive well in
extremely acidic conditions reside. This statement is incorrect. The
rhizosphere is not specifically characterized by microbes that survive in extremely acidic
conditions. While some microbes in the rhizosphere can tolerate various pH levels, this is
not a defining characteristic.
b. The rhizosphere is where microbes that survive well on humans
reside. This statement is incorrect. The rhizosphere is associated with plant roots, not
human-associated microbes.
c. The rhizosphere is where microbes that survive well in the cold
reside. This statement is incorrect. The rhizosphere is not specifically characterized by
cold-loving microbes. (psychrophiles)
d. The rhizosphere is where plants release organic compounds
that can be metabolized by microbes into soil. This statement is
correct. The rhizosphere is the narrow region of soil directly influenced by root secretions
and associated soil microorganisms. Plants release organic compounds into the
rhizosphere, which can be metabolized by microbes.
2. Which environment would contain microbes that are psychrophilic?
, a. Deep-sea hydrothermal vents This statement is incorrect. Deep-sea
hydrothermal vents are characterized by extremely high temperatures, not suitable for
psychrophilic microbes.
b. Glaciers This statement is correct. Psychrophilic microbes thrive in cold environments
such as glaciers, polar regions, and deep ocean waters.
c. Human gut This statement is incorrect. The human gut is a warm environment, not
suitable for psychrophilic microbes.
d. Irradiated food This statement is incorrect. Irradiated food is not a natural
environment for psychrophilic microbes.
3. What is the role of nematodes in soil?
a. They prey on only soil bacteria. This statement is incorrect. Nematodes do
not exclusively prey on soil bacteria; they have a more diverse diet.
b. They decompose dead and decaying biomass. This statement is
incorrect. While some nematodes may contribute to decomposition, this is not their
primary role.
c. They prey on bacteria, smaller nematodes, fungi, and even
plant roots. This statement is correct. Nematodes are diverse in their feeding habits
and can prey on bacteria, smaller nematodes, fungi, and even plant roots.
d. They photosynthesize and fix nitrogen. This statement is incorrect.
Nematodes do not photosynthesize or fix nitrogen.
4. Which eukaryote is responsible for producing antibiotics to ward off
bacterial competitors?
a. Nematodes This statement is incorrect. Nematodes do not produce antibiotics.
b. Tardigrades This statement is incorrect. Tardigrades are not known for producing
antibiotics.
c. Helminths This statement is incorrect. Helminths do not produce antibiotics.
d. Fungi This statement is correct. Fungi are known for producing antibiotics to ward off
bacterial competitors. For example, Penicillium fungi produce penicillin.
Please watch the following videos to help you explain each answer choice
for Lesson 2. (Note: Some of the videos refer to an older version of the
course “C453”. The topics they cover do not differ from the current material,
but references to the previous course may be made.):
Host-Microbe Relationships and Disease Stages
, Reservoirs and Transmission of Pathogens
Section 2 Lesson 2 Quiz
1. Which symbiotic relationship is an example of mutualism?
a. The relationship between humans and Candida albicans of the
vagina This statement is incorrect. Candida albicans can cause infections when it
overgrows, which is not beneficial to humans.
b. The relationship between germinating Bacillus anthracis and
Bacillus anthracis endospores in the soil This statement is incorrect. This
is not a symbiotic relationship but rather a life cycle process of the same organism.
c. The relationship between Staphylococcus epidermidis and
Propionibacterium acnes and other bacteria on the skin This
statement is incorrect. This is an example of commensalism, not mutualism.
d. The relationship between humans and the Escherichia coli
colonizing the human gut This statement is correct. E. coli in the gut helps in
the production of vitamin K, which is beneficial to humans, while the bacteria get a
nutrient-rich environment to live in.
2. Which type of symbiotic relationship exists between the Escherichia
coli (E. coli) that inhabit the human gut and the humans who utilize
the vitamin K produced by E. coli?
a. Commensalism This statement is incorrect. In commensalism, one organism
benefits while the other is neither helped nor harmed. Here, both E. coli and humans’
benefit.
b. Mutualism This statement is correct. Both E. coli and humans benefit from this
relationship.
c. Parasitism This statement is incorrect. In parasitism, one organism benefits at the
expense of the other.
d. Neutralism This statement is incorrect. In neutralism, neither organism affects the
other.
3. Which description of resident microbiota is true?
a. Resident microbiota are always parasites. This statement is incorrect.
Resident microbiota are usually harmless or beneficial.
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