Good Learning Co.
SavannahYear 8
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ScienceHow animal bodies work30 min★★★ difficulty

Guts, enzymes and gut bacteria: carnivore, herbivore, omnivore

You can predict what an animal eats from the length of its gut. Grass is hard to digest, meat is not, and the gut is built to match.

Lesson overview

What you'll learn in this lesson

Understand the tissues and organs of the human digestive system, including the role of enzymes and the importance of bacteria in the gut

Key learning points

  • • One tube, several specialists
  • • Absorption depends on surface area
  • • Bacteria are part of the machinery
  • • Diet predicts gut design

This lesson at a glance

  • 30 minutes
  • 19 parts to scroll through
  • 4 quick checks
  • Marked quiz at the end
  • Gentle pace: short sittings with pauses

Words to know

tissuesorgansdigestivesystemenzymes

Scroll down — the lesson carries on below

Part 1 of 19 · Discover5%
1

Watch & discover

Part 1 of 19

Watch first

Guts, enzymes and gut bacteria: carnivore, herbivore, omnivore

An English teaching video on this topic from Little School. Watch it, then scroll down for the lesson.

In a nutshell

Understand the tissues and organs of the human digestive system, including the role of enzymes and the importance of bacteria in the gut

2

What you already know

Part 2 of 19

Before we start

What you already know

You should already know that food is broken down into smaller molecules that can be absorbed into the blood.

3

Key words

Part 3 of 19

Key words

Words you'll need today

Enzyme
A protein that speeds up a specific reaction, such as breaking down starch.
Villi
Tiny folds of the small intestine wall that increase absorption surface.
Caecum
A pouch in the gut where microbes ferment tough plant material.
Ruminant
A herbivore such as a cow that ferments food in a chambered stomach.
Microbiome
The community of bacteria living in an animal's gut.
4

Learning cycle

Part 4 of 19

Learning cycle 1 of 2

The human digestive line

A short piece of teaching, then a check to make sure it has landed.

5

Explore the idea

Part 5 of 19

Learn

One tube, several specialists

Food is chewed and mixed with amylase in the mouth, churned in acidic stomach juices with protease, then met in the small intestine by enzymes from the pancreas and bile from the liver. Amylase acts on starch, protease on protein and lipase on fats, each producing small soluble molecules.

6

Explore the idea

Part 6 of 19

Learn

Absorption depends on surface area

The small intestine is lined with villi, each covered in microvilli and supplied with blood capillaries. Huge surface area, a wall one cell thick and a rich blood supply keep the concentration gradient steep, exactly as in the lungs.

7

Quick check

Part 7 of 19

Quick check

Which enzyme acts on starch?

8

Quick check

Part 8 of 19

Quick check

Villi increase the rate of absorption mainly by increasing

9

Reset break

Part 9 of 19

Pause

That's sitting 1 of 2 done

Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.

Stop here for now
10

Learning cycle

Part 10 of 19

Learning cycle 2 of 2

Why herbivore guts are longer

A short piece of teaching, then a check to make sure it has landed.

11

Explore the idea

Part 11 of 19

Learn

Bacteria are part of the machinery

Gut bacteria break down fibre humans cannot digest, make some vitamins, and crowd out harmful microbes. Antibiotics can disturb this community, which is one reason digestion is upset during a course of treatment.

12

Explore the idea

Part 12 of 19

Learn

Diet predicts gut design

A cat's gut is short because meat is protein and fat, digestible by its own enzymes. A rabbit has a huge caecum and eats some of its droppings to pass plant material through twice. A cow ferments grass in a four-chambered stomach. None of them makes an enzyme for cellulose — microbes do that work.

13

Quick check

Part 13 of 19

Quick check

Why is a cat's gut relatively short?

14

Quick check

Part 14 of 19

Quick check

A rabbit's large caecum exists to

15

Common mix-ups

Part 15 of 19

Common mix-ups

Things people often get wrong

  • Enzymes are not alive and are not used up; they are reused catalysts.
  • Herbivores do not digest cellulose themselves — their gut microbes ferment it.
  • Stomach acid does not digest everything; most absorption happens further along, in the small intestine.
16

Challenge round

Part 16 of 19

Game · Sort it

Which of these are true?

Drag each card into the right column. Tap a card first if dragging is fiddly.

True

Not true

17

Challenge round

Part 17 of 19

Game · Fill the gaps

Finish the sentences

Choose the word that belongs in each gap.

Food is chewed and mixed with amylase in the mouth, churned in acidic stomach juices with protease, then met in the small intestine by ____ from the pancreas and bile from the liver.

18

Mastery quiz

Part 18 of 19

Marked quiz

End of lesson quiz: Guts, enzymes and gut bacteria: carnivore, herbivore, omnivore

6 questions, marked with the reasoning shown. No timer.

  1. 1. Bile is made by the

  2. 2. Lipase acts on

  3. 3. Gut bacteria help by

  4. 4. A ruminant such as a cow ferments food in its

  5. 5. Most absorption of digested food happens in the

  6. 6. Enzymes are best described as

19

Lesson round-up

Part 19 of 19

Lesson round-up

Ready when you are

Quiz score

Not sat

Games

Not played

Points this lesson

0

Best run

0 in a row

Luna: 0 out of 4 on the practice checks. Only if you feel up to it — one more?

Ask Luna

Do the work

Your written work for this lesson

This is the part you'd do in your book at school. Pick the pieces below, write here or on paper, and photograph anything you draw or work out.

Case study

Why the school greenhouse failed

A science club grew tomato plants in the school greenhouse. In June the plants grew well: leaves were dark green and the fruit set quickly. In July the club went away for two weeks and left the greenhouse door shut. When they came back, the leaves were curled and pale and most of the fruit had dropped.

The club had a data logger inside. It showed the temperature reached 46 °C on several afternoons and the soil moisture fell close to zero. The club knew photosynthesis needs light, water and carbon dioxide, and that enzymes in a plant work best in a narrow range of temperature. Above that range the enzymes stop working properly.

The club repeated the summer with the door propped open and a water bottle drip on each pot. Temperature peaked at 31 °C and the plants survived.

Written for Good Learning Co.

Reading questions

  1. Name the variable the club changed the second time, and one variable they kept the same.
  2. Explain, using the words photosynthesis and enzymes, why the plants were damaged in July.
  3. Write a conclusion for the club's report, saying how far the evidence supports it.

  • Method and results

    Writing

    Write the aim, what you changed, what you measured and what you kept the same, then record your results in a table.

    1 page + results table

  • Conclusion

    Writing

    Explain what your results show and why, using the scientific words from the lesson. Say how you know you can trust them.

    6–8 sentences

  • Labelled diagram

    Diagram

    Draw the apparatus or the process in pencil, label it fully, and photograph it.

    1 labelled diagram

  • Reading and notes

    Reading

    Read the lesson text again and write the key ideas in your own words.

    Half a page of notes

Saved as you type.

Part 1 of 19 · Watch & discover

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