Digestion and the gut
Digestion breaks huge food molecules into tiny ones your body can absorb — and it needs both chemical helpers and a whole community of bacteria.
Part of your national curriculum
- Biology: structure and function: Understand the tissues and organs of the human digestive system, including the role of enzymes and the importance of bacteria in the gut
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
- • The journey of food
- • Enzymes speed up digestion
- • Gut bacteria
This lesson at a glance
- 28 minutes
- 14 parts to scroll through
- 3 quick checks
- Marked quiz at the end
- Gentle pace: short sittings with pauses
Words to know
Scroll down — the lesson carries on below
Watch & discover
Part 1 of 14
Watch first
Digestion and the gut
An English teaching video on this topic from Explore Planet English. 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
Learning cycle
Part 2 of 14
Learning cycle 1 of 2
Part 1 · The journey of food
A short piece of teaching, then a check to make sure it has landed.
Explore the idea
Part 3 of 14
Learn
The journey of food
Food travels from the mouth through the oesophagus to the stomach, then the small intestine, where most digestion and absorption happens, and finally the large intestine, where water is absorbed before waste leaves as faeces.
Explore the idea
Part 4 of 14
Learn
Enzymes speed up digestion
Enzymes are biological catalysts. Amylase (in saliva and the small intestine) breaks starch into sugars; protease breaks proteins into amino acids; lipase breaks fats into fatty acids and glycerol. Each enzyme works best at a specific pH and temperature.
Quick check
Part 5 of 14
Quick check
What does amylase break down?
Reset break
Part 6 of 14
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.
Quick check
Part 7 of 14
Quick check
Where does most digestion and absorption occur?
Learning cycle
Part 8 of 14
Learning cycle 2 of 2
Part 2 · Gut bacteria
A short piece of teaching, then a check to make sure it has landed.
Explore the idea
Part 9 of 14
Learn
Gut bacteria
Trillions of bacteria live in the large intestine. They help break down fibre that human enzymes cannot digest, produce some vitamins (such as vitamin K), and support the immune system by competing with harmful microbes for space and food.
Quick check
Part 10 of 14
Quick check
What is one benefit of gut bacteria?
Challenge round
Part 11 of 14
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
Challenge round
Part 12 of 14
Game · Fill the gaps
Finish the sentences
Choose the word that belongs in each gap.
____ are biological catalysts.
They help break down fibre that human enzymes cannot digest, produce some vitamins (such as vitamin K), and support the immune ____ by competing with harmful microbes for space and food.
Mastery quiz
Part 13 of 14
Marked quiz
End of lesson quiz: Digestion and the gut
3 questions, marked with the reasoning shown. No timer.
1. What does amylase break down?
2. Where does most digestion and absorption occur?
3. What is one benefit of gut bacteria?
Lesson round-up
Part 14 of 14
Lesson round-up
Ready when you are
Quiz score
Not sat
Games
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Points this lesson
0
Best run
0 in a row
Luna: 0 out of 3 on the practice checks. Only if you feel up to it — one more?
Ask LunaDo 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.
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
- Name the variable the club changed the second time, and one variable they kept the same.
- Explain, using the words photosynthesis and enzymes, why the plants were damaged in July.
- Write a conclusion for the club's report, saying how far the evidence supports it.
Method and results
WritingWrite 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
WritingExplain 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
DiagramDraw the apparatus or the process in pencil, label it fully, and photograph it.
1 labelled diagram
Reading and notes
ReadingRead 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 14 · Watch & discover
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Understand the tissues and organs of the human digestive system, including the role of enzymes and the importance of bacteria in the gut