What is an ecosystem?
an experiment in which people were placed inside a room that was as free of microbes as possible
a species of bacteria that can help protect our skin against fungi and yeast but can also cause infections and life-threatening diseases
a community of living things that interact with each other and with the non-living things in their environment
a group of scientists studying how microorganisms work in our bodies, and learning about the balance among different bacterial communities
To organize this text, the author divides it into sections with subheadings. What is described in the section with the subheading “You Are an Ecosystem”?
microbes in and on the human body
plants and animals living in the ocean
an experiment in which scientists measured bacterial “clouds”
the effects of antibiotic drugs on our microbiomes
Humans and microbes have “complex relationships.”
What information in the article best supports this statement?
Scientists call bacteria that are harmless to humans “commensal.”
Antibacterial hand sanitizers can wipe out all bacteria on a patch of skin.
Microbes are the oldest form of life on Earth, having first appeared over 3.5 billion years ago.
Some microbes benefit humans, while other microbes harm humans.
Read these sentences from the text.
“Scientists repeated the experiment many times, and could always tell which room had been occupied. They could measure bacterial ‘clouds’ in the room—bacteria that had come off the person’s body. Because every person’s microbiome is unique, they could also identify different people from their bacterial ‘clouds.’”
Why might the author have placed the word “clouds” in quotation marks?
to indicate that the word is being used in a different way than usual
to quote the scientists who were doing the experiment
to express surprise that clouds appeared inside a room
to suggest that the measurements recorded by the scientists may not have been accurate
What is the main idea of this text?
No two human microbiomes are the same.
The human body is a diverse ecosystem made up of microbes.
Some bacteria cause infections and even life-threatening diseases.
Some scientists think that infants who lack exposure to microorganisms develop a higher rate of allergies.
