Q: Which equation best represents the exponential growth rate of bacteria in the intestinal tract, given 1-2 doublings per day?

$$N_t = N_0$ \times 2$$^{d}$$ where d$ is the number of doublings$

Question 1

Which of the following statements best describes the difference between microbiome and microbiota?

Accepted Answer

Microbiome refers to the functional collection of different microbes in a particular environmental system, while microbiota refers to all the microbes in a microhabitat.

Question 2

Which factor is LEAST likely to influence the composition and density of skin flora?

Accepted Answer

Blood glucose levels

Question 3

A patient presents with frequent respiratory infections. Which of the following is most likely to be true about their lower respiratory tract microbiota?

Accepted Answer

It is normally sterile in healthy adults.

Question 4

Which of the following is a major metabolic contribution of intestinal microorganisms?

Accepted Answer

Synthesis of vitamins such as B12 and K

Question 5

Which genus is the predominant organism on the human back skin, according to microbiome studies?

Accepted Answer

Propionibacterium

Question 6

Which of the following best explains why sweat can produce body odor?

Accepted Answer

Bacterial species on the skin metabolize sweat components, producing volatile compounds such as butyric acid and ammonia.

Question 7

Which of the following is a plausible consequence of decreased microbial diversity in the gut of aging individuals?

Accepted Answer

Decreased production of bioactive molecules such as propionic acid

Question 8

Which of the following is a function of bacteriophages in the human virome?

Accepted Answer

They provide a form of host-independent immunity by defending against pathogens in mucosal surfaces.

Question 9

A fecal transplant is most beneficial for patients suffering from which infection?

Accepted Answer

Clostridium difficile

Question 10

Which equation best represents the exponential growth rate of bacteria in the intestinal tract, given 1-2 doublings per day?

Accepted Answer

$$N_t = N_0$ 	imes 2$$^{d}$$ where d$ is the number of doublings$

Question 11

Which of the following is a major member of the gastrointestinal tract microbiota and is associated with enterotype #1?

Accepted Answer

Bacteroides

Question 12

Which antimicrobial enzyme is found in saliva and helps control oral microbiota?

Accepted Answer

Lysozyme

Question 13

Which of the following is NOT a plausible reason for the absence of normal microbiota in the lower respiratory tract of healthy adults?

Accepted Answer

High concentrations of nutrients promote microbial growth.

Question 14

Which of the following best describes the relationship between diet and gut microbiota composition?

Accepted Answer

Diet influences the enterotype, which in turn affects response to diet and drug therapy.

Question 15

Which of the following is a major physiological process occurring in the colon, facilitated by its microbiota?

Accepted Answer

Absorption of bile acids and vitamin $$B_{12}$$

Question 16

Which of the following is the predominant bacteria in the vagina between puberty and menopause?

Accepted Answer

Lactobacillus acidophilus

Question 17

Which of the following best describes the effect of circumcision on penile microbiota?

Accepted Answer

It lessens the amount and composition of microbiota.

Question 18

Which of the following is a plausible explanation for why most bacteria cannot be cultured from human microbiome samples?

Accepted Answer

They require specific nutrients and environmental conditions not replicated in laboratory media.

Question 19

Which of the following is a plausible effect of smoking on the respiratory tract microbiota, based on real-world data?

Accepted Answer

Smoking increases the abundance of Proteobacteria in the respiratory tract.

Question 20

Which of the following best describes the colonization of the human microbiome prior to birth?

Accepted Answer

Oral bacteria from the mother are found in the placenta, and microbes are present in amniotic fluid and fetal meconium.

Microbial Symbioses with Humans: The Human Microbiome

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