The Bacteria That Help You Digest

Science · Organisms & Life Processes · ages 12-13

Name ______________________ Date ____________

What can gut bacteria break down that your digestive enzymes cannot?
- Sugar from fruit
- Fibre from plants
- Water you drink
Most bacteria living in your gut are...
- Helpful and work with your body
- Harmful and should be avoided
- Not really alive
If your gut bacteria are wiped out, your digestion can be thrown off balance.
Circle one: True False
Look at the bar chart of bacteria in a healthy gut. How many more helpful bacteria units are there than harmful ones?
Answer: ______________
Layla eats a salad full of leafy vegetables. Her enzymes break down the sugars, but what happens to the tough fibre in the leaves?
- It passes through completely undigested, doing nothing
- Her stomach acid dissolves all of it
- Gut bacteria in her large intestine ferment it
A doctor prescribes antibiotics to treat a throat infection. Besides killing the bacteria causing it, what else might happen?
- Helpful gut bacteria can be killed too, disrupting digestion
- Nothing else changes
- Digestive enzymes stop working permanently
A scientist compares two children's gut samples. One child recently finished a two-week course of strong antibiotics; the other did not take any. What would you expect, and why?
- The treated child will have more gut bacteria, since antibiotics feed bacteria
- There will be no difference, antibiotics only affect the throat
- The treated child likely has fewer types of gut bacteria, since antibiotics reduce bacteria broadly
Ben says: "Since bacteria make me sick when I have an infection, I should get rid of all the bacteria in my gut to stay healthy." What is wrong with Ben's thinking?
- Nothing, fewer bacteria is always better
- Most gut bacteria are helpful, and removing them would harm his digestion
- Bacteria in the gut are not real, they are germs

Answer key

For grown-ups. Fold this page away before handing over the rest.

The Bacteria That Help You Digest W1-mt_fCvmdI6xGO-s1

Fibre from plants · Fibre is too tough for human enzymes, so gut bacteria ferment it instead.
Helpful and work with your body · Only a small number of gut bacteria can cause harm. Most help you digest food and stay healthy.
True · Losing gut bacteria removes helpers your body relies on for digesting fibre and keeping the gut balanced.
80 · 90 minus 10 is 80, showing helpful bacteria far outnumber harmful ones.
Gut bacteria in her large intestine ferment it · Enzymes handle sugars and proteins, but fibre needs gut bacteria to break it down further.
Helpful gut bacteria can be killed too, disrupting digestion · Antibiotics can't tell helpful bacteria from harmful ones, so they often reduce gut bacteria overall.
The treated child likely has fewer types of gut bacteria, since antibiotics reduce bacteria broadly · Antibiotics travel through the body and reduce gut bacteria along with the bacteria causing illness, which is why gut diversity often drops afterward.
Most gut bacteria are helpful, and removing them would harm his digestion · Ben is confusing disease-causing bacteria with the helpful bacteria that live in a healthy gut and support digestion.