The Gut's Gas Ledger: teacher key

Burps and Farts, grade 10 edition, written for 10th grade. A gut makes more gas than a person ever passes, because other microbes use some up and the blood absorbs some. Which foods leave the most for bacteria to ferment, and how the numbers are measured, explain much of the rest.

Read the book. Print this page for the key.

Questions and answers

1. Gas made by gut bacteria can leave by which routes?
   • Only out the bottom as a fart
   • Used up by other microbes, absorbed and breathed out, or passed as a fart (answer)
   • Only absorbed into the blood
2. Which food leaves only about 1 percent of its carbohydrate unabsorbed?
   • Baked beans
   • White rice (answer)
   • Potatoes
3. A diet with no fiber cut one person's daily gas from about 700 milliliters to about 200. What does that suggest?
   • Fiber gives bacteria more to ferment (answer)
   • Bacteria make gas without any food
   • Fiber has no link to gas
4. Why might two people eating the same dinner make different amounts of gas?
   • They have more or different bacteria in the gut (answer)
   • Only one of them swallows food
   • Gas only comes from air
5. In this passage, what does it mean that bacteria ferment food?
   • They break down food that was not digested earlier and give off gas (answer)
   • They make the food fizzy before it is eaten
   • They stop food from moving through the gut

Words

• ferment: break food down
• oligosaccharides: hard-to-digest sugars
• soluble: dissolves in water
• microbiome: gut microbe community
• flatologist: gas scientist