Q: Which equation best represents the ratio of bacterial cells to human cells in the human body?

$$\frac{\text{Bacterial cells}}{\text{Human cells}} \approx 10$$

Question 1

Which of the following statements best describes the human microbiome?

Accepted Answer

It is the collection of microbes and their genes living on and inside a human.

Question 2

Approximately how many microbial cells are present in the human body?

Accepted Answer

10-100 trillion

Question 3

Which function is NOT typically performed by the human gut microbiome?

Accepted Answer

Produce insulin

Question 4

A newborn's initial microbiome composition is most strongly influenced by which factor?

Accepted Answer

Mode of delivery (vaginal birth vs. C-section)

Question 5

Why is the diversity of the fecal microbiome generally higher than that of the tongue microbiome?

Accepted Answer

The gut provides a more stable and nutrient-rich environment for diverse microbes.

Question 6

Which medical intervention is most likely to disrupt the normal gut microbiome and reduce its diversity?

Accepted Answer

Administration of antibiotics

Question 7

After a course of antibiotics, which intervention has been shown to most effectively restore the gut microbiome to its baseline composition?

Accepted Answer

Fecal matter transplant (FMT)

Question 8

Which of the following is a plausible consequence of long-term disruption of the gut microbiome by antibiotics?

Accepted Answer

Increased risk of inflammation and obesity

Question 9

If a baby is delivered via C-section, which microbiome is it most likely to be seeded with?

Accepted Answer

Mother's skin microbiome

Question 10

Which equation best represents the ratio of bacterial cells to human cells in the human body?

Accepted Answer

$$\frac{	ext{Bacterial cells}}{	ext{Human cells}} \approx 10$$

Question 11

Which of the following is a reason why comparing tongue and fecal microbiomes is scientifically valuable?

Accepted Answer

It reveals differences in taxonomic diversity and functional roles across body sites.

Question 12

Which statement about the relative abundance of bacterial phyla in the tongue and fecal microbiomes is correct?

Accepted Answer

The fecal microbiome has higher overall diversity than the tongue microbiome.

Question 13

Which of the following best describes the effect of probiotics after antibiotic treatment, according to experimental studies?

Accepted Answer

Probiotics delay recovery compared to fecal matter transplant.

Question 14

Which of the following is NOT an essential function performed by microbes in the human body?

Accepted Answer

Synthesis of hemoglobin

Question 15

Which scenario best illustrates a multi-step disruption and recovery of the gut microbiome?

Accepted Answer

A patient receives antibiotics, then a fecal matter transplant, resulting in rapid restoration of microbial diversity.

Question 16

Which of the following best explains why microbial diversity is important for human health?

Accepted Answer

It supports essential functions such as nutrient extraction, vitamin synthesis, and immune regulation.

Question 17

If $$D$$ represents microbial diversity and $$A$$ represents antibiotic exposure, which equation best models the effect of antibiotics on diversity over time?

Accepted Answer

$$D_{post} = D_{pre} - A$$

Question 18

Which of the following is a plausible outcome of vaginal seeding in infants delivered by C-section?

Accepted Answer

Promotion of a microbiome with fewer health risk factors.

Question 19

Which of the following best describes the relationship between microbial cells and human genes in the human body?

Accepted Answer

There are more bacterial genes than human genes.

Question 20

Which of the following best explains why recovery of the gut microbiome after antibiotics can take years?

Accepted Answer

Antibiotics reduce microbial diversity, and natural recolonization is slow and incomplete.

Human Microbiome: Diversity, Acquisition, and Medical Impacts

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