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What Do You Know About the Human Microbiome?

Test your knowledge about the microbes that live in and on us in this 10-question quiz!

Icons representing a man and a woman covered with mysterious geometrical shapes.
1

Why do scientists call humans "superorganisms"?

 

humans are the smartest organisms on Earth

 

humans are an ecosystem for many other organisms

 

humans are such large organisms compared to most

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ANSWER: humans are an ecosystem for many other organisms

You are a superorganism because your body is an ecosystem. It is home to trillions of microbes that form communities in different places in and on your body. Together these communities make up your microbiome .

Question 1 of 10
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Three human icons with different proportions of their bodies covered by little dots.
2

What percent of all the cells  in the human body are bacterial cells?

 

less than 10%

 

about 30%

 

more than 70%

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ANSWER: more than 70%

Scientists estimate the human body is made of about 100 trillion bacterial cells. That's between 70 to 90 percent of all cells in your body! And the bacteria's genes make up about 99 percent of all the genes in your body.

Question 2 of 10
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Icon of a person covered/filled with geometric shapes, waving.
3

How do microbes keep us healthy?

 

they produce vitamins

 

they boost our immune system

 

they produce vitamins and boost our immune system

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ANSWER: they produce vitamins and boost our immune system

While some microbes can make us sick, many more keep us healthy from head to toe. Microbes in our brain  affect our mood, while microbes on our toes kill the fungus that causes athlete's foot. Others kill off harmful bacteria, help us digest food, and prevent tooth decay.

Question 3 of 10
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Icon of a person with three different areas of the body defined (forehead,Oily. Armpit, warm and wet. Knee, cool and dry)
4

From the point of view of a microbe, your skin has lots of habitats . Which area has the greatest diversity of microbes?

 

your knee

 

your forehead

 

your armpit

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ANSWER: your knee

On the cool and dry skin of your knee, the bacteria are fewer but more diverse, with hundreds of kinds that come and go.

Question 4 of 10
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Icons of a hamburger and a dog.
5

Every human has a different set of microbes. What accounts for these differences?

 

what you eat

 

who you live with

 

what you eat and who you live with

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ANSWER: what you eat and who you live with

In fact, many different things affect your microbiome : your diet, your washing habits, and whether you have a dog, are just a few.

Question 5 of 10
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Icon of the digestive system, with labels for the stomach, large and small intestine.
6

Where do most of the bacteria in your body live?

 

in your stomach

 

in your small intestine

 

in your large intestine

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ANSWER: in your large intestine

Ninety-nine percent of your body's microbes live in your large intestine or colon. Trillions of microbes ferment food you can't digest, produce nutrients, and protect your gut lining.

Question 6 of 10
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Icon of a bacteria eating burgers.
7

Many kinds of bacteria live in your digestive system. Where do they get their food?

 

from the food you eat

 

from your blood system

 

from your saliva and gastric "juices"

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ANSWER: from the food you eat

The food you eat feeds bacteria in your digestive system. They're like pets to feed and care for! Foods that feed beneficial bacteria include beans, vegetables, fruit, and whole grains. These are called prebiotics.

Question 7 of 10
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Person with a belly ache surrounded by icons of pills (antibiotics).
8

What is a potential risk of taking too many antibiotics for infections?

 

antibiotics "feed" the harmful bacteria

 

antibiotics kill bacteria that keep us healthy

 

there is no risk taking antibiotics

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ANSWER: antibiotics kill bacteria that keep us healthy

Antibiotics don't just kill harmful bacteria, they can also kill beneficial ones. Also, over time, harmful bacteria may become resistant to antibiotics.

Question 8 of 10
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Sad face surrounded by a peanut, ice cream and a shrimp.
9

Your body's microbes help "train" your immune system to know what to attack and what not to. What happens when your immune system attacks a normally harmless food?

 

you get a stomach ache

 

you have an allergic reaction

 

you don't notice any changes

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ANSWER: you have an allergic reaction

An allergy is an immune response to a normally harmless food or the environment. If your immune system attacks peanuts or pollen, you have an allergic reaction.

Question 9 of 10
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A microbe "flexing muscles" to show it is strong next to a jar of yogurt with microbes in it.
10

Why is yogurt considered a probiotic?

 

it destroys bacteria

 

it helps build strong bones

 

it contains live, helpful bacteria

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ANSWER: it contains live, helpful bacteria

A probiotic is anything that contains live organisms that are good for you. The live bacteria in yogurt boost your immune system and help keep out bacteria that cause disease.

Question 10 of 10
Nice try! Good try! Well done! A perfect score! You got out of 10 right on the first guess.