Question 1

Which of the following best describes mutualism in the context of microbial communities?

Accepted Answer

A relationship where both organisms benefit from the interaction.

Question 2

Which of the following is NOT a function of the human microbiome?

Accepted Answer

Directly attacking viruses in the bloodstream.

Question 3

A patient is prescribed broad-spectrum antibiotics and subsequently develops severe diarrhea. Which of the following best explains this outcome?

Accepted Answer

The antibiotics suppressed normal gut microbiota, allowing Clostridium difficile to overgrow.

Question 4

Which of the following statements about Mucosal-Associated Lymphoid Tissue (MALT) is correct?

Accepted Answer

MALT provides a moist, mucus-rich environment that supports the microbiota.

Question 5

Which of the following is a plausible consequence of dysbiosis in the gut microbiome?

Accepted Answer

Development of inflammatory bowel disease.

Question 6

Which of the following best explains why the skin microbiome is dominated by Gram-positive bacteria?

Accepted Answer

Gram-positive bacteria are more resistant to high salt, low pH, and dry conditions.

Question 7

Which of the following is a direct benefit of the microbiota occupying mucosal surfaces?

Accepted Answer

They prevent pathogen attachment by occupying available niches.

Question 8

A sudden switch in a cow’s diet from hay to grain leads to rapid growth of Streptococcus bovis in the rumen. What is the most likely consequence?

Accepted Answer

Acidosis due to lactic acid accumulation, potentially causing inflammation and death.

Question 9

Which of the following best describes the role of methanogenic archaea in the rumen?

Accepted Answer

They remove $$\mathrm{H}_2 by $$converting it to methane, promoting fermentation.

Question 10

Which of the following is a reason why normal microflora do NOT colonize internal organs, blood, lymph, or the nervous system?

Accepted Answer

These environments are sterile, and colonization indicates serious infection.

Question 11

Which of the following is a correct statement about the oral microbiome?

Accepted Answer

It contains both aerobic and anaerobic microbes, including bacteria, archaea, and yeast.

Question 12

Which of the following best explains why fecal microbiota transplantation (FMT) can be effective in treating recurrent C. difficile infections?

Accepted Answer

FMT restores a healthy and diverse gut microbiome, which suppresses C. difficile overgrowth.

Question 13

Which of the following is a function of the gut microbiome related to host metabolism?

Accepted Answer

Synthesis of volatile fatty acids (VFAs) from complex carbohydrates.

Question 14

Which of the following best describes the Red Queen Hypothesis as it relates to microbial communities?

Accepted Answer

Species must constantly adapt and evolve to survive against ever-evolving opposing organisms.

Question 15

Which of the following is a limitation of Koch’s postulates when applied to identifying members of the normal microflora?

Accepted Answer

Normal microflora do not always cause disease, so they do not fulfill Koch’s postulates.

Question 16

Which of the following factors does NOT significantly influence the composition of the human microbiome?

Accepted Answer

Blood type.

Question 17

Which of the following best explains why the lower respiratory tract is typically free of resident microflora in healthy adults?

Accepted Answer

Ciliated epithelial cells and mucus trap and remove microorganisms before they reach the lower tract.

Question 18

Which of the following is a plausible effect of a decrease in 'peace-keeping' bacteria in the gut?

Accepted Answer

Pathological inflammation and increased susceptibility to disease.

Question 19

Which of the following is a correct statement about the relationship between obesity and the gut microbiome?

Accepted Answer

Obese individuals often have increased Firmicutes and methanogenic archaea.

Microbial Communities and the Human Microbiome

Study Guide - Practice Questions