What Do You Know About the Human Microbiome?

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

Answer explanation

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 .

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

• Less than 10%

• About 30%

• More than 70%

Answer explanation

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.

How do microbes keep us healthy?

• They produce vitamins

• They boost our immune system

• They provide vitamins and boost our immune system

Answer explanation

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.

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

• Knee

• Forehead

• Armpit

Answer explanation

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

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

Answer explanation

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

Where do most bacteria in your body live?

• In your stomach

• In your large intestine

• In your small intestine

Answer explanation

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.

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

• From the food you eat

• From your bloodstream

• From your saliva and gastric “juices”

Answer explanation

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.

What is the 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

Answer explanation

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

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 a allergic reaction

• You don’t notice any changes

Answer explanation

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.

Why is yogurt considered a probiotic?

• It destroys bacteria

• It helps build strong bones

• It contains live, helpful bacteria

Answer explanation

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.