Question 1

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

Accepted Answer

Microbiome is the functional collection of different microbes in a particular environment, while microbiota refers to the types of organisms present in that habitat.

Question 2

Which methodology has played a major role in identifying the diversity and abundance of different groups within the human microbiome?

Accepted Answer

Metagenomics

Question 3

Which of the following statements about the large intestine is correct?

Accepted Answer

It acts as an in vivo fermentation vessel, with microbiota using nutrients derived from digestion of food.

Question 4

Which bacterial group is most abundant in human feces?

Accepted Answer

Bacteroidetes

Question 5

What is a key function of Lactobacillus acidophilus in the adult female vagina?

Accepted Answer

It ferments glycogen, producing lactic acid to maintain a weakly acidic environment.

Question 6

Which of the following factors does NOT influence the composition of the skin microbiota?

Accepted Answer

Blood type

Question 7

Why does the lower respiratory tract have no naturally resident microbiota?

Accepted Answer

Microbes are trapped in mucus and expelled or killed in the stomach before reaching the lower tract.

Question 8

Which of the following is a consequence of antibiotic use in early life?

Accepted Answer

Increased risk of developing IBD and other disorders related to dysbiosis

Question 9

Which equation best represents the production of lactic acid by Lactobacillus acidophilus in the vagina?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$} \rightarrow 2\ \mathrm{CH_3CH(OH)COOH}$$

Question 10

Which of the following is TRUE regarding the effect of birth method on gut microbiota colonization?

Accepted Answer

Vaginally delivered infants acquire microbiota resembling their mother's vaginal and intestinal flora.

Question 11

Which of the following is a product of intestinal microbiota that helps 'educate' the immune system?

Accepted Answer

Short-chain fatty acids such as butyric acid

Question 12

Which scenario best illustrates the concept of dysbiosis?

Accepted Answer

Chronic inflammation of the gut due to disruption of homeostasis and reduced microbiome diversity.

Question 13

Obese humans tend to have higher levels of which microbial groups compared to lean humans?

Accepted Answer

Prevotella and methanogens

Question 14

Which process is most directly responsible for the formation of dental caries?

Accepted Answer

Biofilm formation by fermenting bacteria producing acid that wears down tooth enamel.

Question 15

Which of the following is a plausible outcome of fecal transplants?

Accepted Answer

Curing C. difficile infections by restoring healthy microbiota.

Question 16

Which of the following is a common probiotic bacterium found in commercial products?

Accepted Answer

Lactobacillus

Question 17

Prebiotics are best described as:

Accepted Answer

Carbohydrates indigestible by humans but provide nutrition for fermentative gut bacteria.

Question 18

Which equation best represents the production of methane by gut methanogens?

Accepted Answer

$$\mathrm{CO_2$} + 4\ \mathrm{H_2$} \rightarrow \mathrm{CH_4$} + 2\ \mathrm{H_2O}$$

Question 19

Which of the following is a plausible effect of oral antibiotics on the human gut microbiome?

Accepted Answer

Reduction in both target and non-target microbial populations, leading to loss of community diversity.

24. Microbial Symbioses With Humans: The Human Microbiome and Its Impact

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