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Bacteria in the human digestive system
I can describe the important roles of bacteria in the human digestive system.
Lesson 4 of 5
New
New
- Year 8
Bacteria in the human digestive system
I can describe the important roles of bacteria in the human digestive system.
Lesson details
Key learning points
- Bacteria are living organisms; each bacterium is a microorganism made of a single living cell.
- Some bacteria are pathogens that cause diseases, but many bacteria are harmless and some are helpful.
- Helpful bacteria live inside the human digestive system.
- They release enzymes that digest food we cannot digest ourselves.
- They also help to protect us against pathogens that enter the digestive system by competing against them.
Keywords
Bacteria - Bacteria are unicellular organisms.
Microorganism - A microorganism is an organism that can only be seen using a microscope.
Pathogen - A pathogen is a microorganism that causes disease.
Enzyme - An enzyme is a biological catalyst that speeds up the rate of reaction such as digestion.
Competition - Competition occurs between living organisms, e.g. bacteria competes for food and space to live.
Common misconception
All bacteria are bad for us and make us unwell.
The lesson looks at how helpful bacteria in the gut help us digest our food, provide vitamins, and outcompete harmful bacteria.
Encourage students to add their own opinions into the discussion of the three students in Task B, and explore this verbally before writing a response.
Teacher tip
Equipment
Licence
This content is © Oak National Academy Limited (2026), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.The smallest living part of an organism (such as plant, animal or bacteria) is called a...
The smallest living part of an organism (such as plant, animal or bacteria) is called a...
nucleus
molecule
tissue
system
Q2.Which of the following are found in a bacteria cell?
Which of the following are found in a bacteria cell?
mitochondria
chloroplasts
Q3.After we have swallowed food it moves through the oesophagus and then moves into the...
After we have swallowed food it moves through the oesophagus and then moves into the...
Q4.In which of these parts of the digestive system does most digestion take place?
In which of these parts of the digestive system does most digestion take place?
stomach
large intestine
rectum
liver
Q5.Match the food type to the nutrients it is broken down into.
Match the food type to the nutrients it is broken down into.
Q6.Enzymes the rate of a chemical reaction, such as digestion.
Enzymes the rate of a chemical reaction, such as digestion.
Assessment exit quiz
6 Questions
Q1.What are pathogens?
What are pathogens?
All bacteria.
Bacteria used to make food.
Bacteria that produce enzymes.
Q2.Which people are correct?
Which people are correct?
Izzy: "Bacteria should only be found outside the body."
Sam: "Bacteria are always harmful to human health."
Q3."Gut flora" means the in our digestive system.
"Gut flora" means the in our digestive system.
Q4.Bacteria produce that digest food we can't digest ourselves.
Bacteria produce that digest food we can't digest ourselves.
Q5.Which of the following do bacteria compete for?
Which of the following do bacteria compete for?
enzymes
pathogens
Q6.Which of the following will help us maintain a healthy gut flora?
Which of the following will help us maintain a healthy gut flora?
Eating lots of protein.
Eating food with a high sugar content.
