Questions for ‘The bugs within us’

Microbes, such as this fungi (Malassezia lopophilis), are part of the human microbiome. This fungus, which has been colorized to show up well, is commonly found on human skin.

Janice Haney Carr, CDC

To accompany feature: The bugs within us


Before reading:

1.    Bacteria live everywhere. Where would you expect to find especially large numbers of them in your home?

2.    Research the roles bacteria and other microbes play in making these food products: beer, cheese, bread, pickles and yogurt.

During reading:

1.    By cell count, are you mostly human or bacterial? How about by mass?

2.    What are some of the sources of the bacteria that live on and in us?

3.    Name one important role bacteria play in our health.

4.    Explain why “tit for tat” helps explain our relationship with bacteria.

5.    Define “microbiome.”

6.    Why is the blood-brain barrier so important?

7.    What exciting role might bacteria play in the development of the blood-brain barrier?

8.    Explain what seems to lure fruit fly larvae to a new food source.

9.    When do fly larvae expel the chemicals called volatiles?

10. Based on the facts presented in the story, why is an animal’s scent so important?

After reading:

1.    Explain why giving antibiotics to newborn babies might affect the development of their brains. What evidence does the story cite for this?

2.    Bacteria appear to play a role in the mating choices made by at least some animals. How might that benefit the bacteria?


1.    Weigh yourself. Now, using the estimated percentages provided in this story, calculate the range of masses (likely weights) of your microbiome.

2.    Convert into a percentage the ratio (as described in the story) of estimated bacterial cells to human cells in your body.