Question 1

Which of the following best describes the difference between resident and transient microbiota?

Accepted Answer

Resident microbiota are introduced at birth and remain permanently, while transient microbiota are temporarily present and eliminated by host defenses.

Question 2

A patient is taking broad-spectrum antibiotics for a bacterial infection. Which of the following is a likely consequence related to their microbiota?

Accepted Answer

The antibiotics may disrupt the resident microbiota, allowing opportunistic pathogens to cause infection.

Question 3

Which of the following is a key reason why most resident microbiota are beneficial to the host?

Accepted Answer

They compete with potential pathogens for nutrients and attachment sites, a process known as microbial antagonism.

Question 4

Which genus of bacteria is primarily responsible for the acidic environment of the vagina, and what is the effect of this acidity?

Accepted Answer

Lactobacillus; the acidity inhibits the growth of pathogens such as Clostridium.

Question 5

Which of the following scenarios best illustrates an opportunistic infection caused by resident microbiota?

Accepted Answer

A patient with a compromised immune system develops pneumonia caused by a normally harmless species of resident microbiota.

Question 6

Which of the following statements about transient microbiota is correct?

Accepted Answer

They are temporarily present on body surfaces and are eliminated by host defenses or competition from resident microbiota.

Question 7

If a microbe cannot attach to host tissues, what is the likely outcome according to the study materials?

Accepted Answer

No residence and no infectious disease will be established.

Question 8

Which of the following best describes the relationship of commensalism in the context of resident microbiota?

Accepted Answer

One organism benefits while the other is unaffected.

Question 9

A newborn is delivered via cesarean section and is not immediately exposed to the mother's vaginal microbiota. Which of the following is a likely effect on the newborn's microbiome?

Accepted Answer

The newborn may have a different initial microbiota composition compared to a vaginally delivered infant.

Question 10

Which of the following is an example of mutualism between resident microbiota and the human host?

Accepted Answer

Bacteria in the gut synthesize vitamins that are absorbed by the host, while the bacteria receive nutrients and a place to live.

Question 11

Which of the following is a correct statement about probiotics based on the study materials?

Accepted Answer

Probiotics can restore resident microbiota populations on the surface of the digestive tract during antibiotic therapy.

Question 12

Which of the following best explains why Staphylococcus aureus is considered an opportunistic pathogen?

Accepted Answer

It is usually harmless but can cause disease if it gains access to deeper tissues or if the host is immunocompromised.

Question 13

Which of the following is NOT a typical external surface colonized by resident microbiota?

Accepted Answer

Bloodstream

Question 14

Which of the following best describes the role of Lactobacillus acidophilus in the human body?

Accepted Answer

It is a beneficial bacterium found on the surface of the intestinal tract and is also used in probiotics.

Question 15

A patient develops a fungal infection after a course of antibiotics. Which concept best explains this phenomenon?

Accepted Answer

The antibiotics disrupted the resident microbiota, reducing microbial antagonism and allowing opportunistic fungi to proliferate.

Question 16

Which of the following is a necessary condition for an infectious disease to be established by a microbe?

Accepted Answer

The microbe must attach to host tissues.

Question 17

Which of the following best describes the concept of microbial antagonism?

Accepted Answer

Resident microbiota inhibit the growth of potential pathogens by competing for nutrients and attachment sites.

Question 18

Which of the following is a plausible outcome if the vaginal pH increases significantly?

Accepted Answer

There may be a decrease in Lactobacillus populations and an increased risk of infection by pathogens such as Clostridium.

Question 19

Which of the following is an example of a mutualistic relationship involving the intestinal microbiota?

Accepted Answer

Bacteria in the gut help digest complex carbohydrates, providing nutrients for both themselves and the host.

Question 20

Which of the following best explains why transient microbiota do not usually cause disease in healthy individuals?

Accepted Answer

They are eliminated by host defenses or outcompeted by resident microbiota before they can establish residence.

Normal Microbiota: Classification, Distribution, and Host Relationships

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