New
New
Year 8

Digestion and enzymes

I can describe the processes of mechanical and chemical digestion that break down food to release nutrients, including the role of enzymes.

New
New
Year 8

Digestion and enzymes

I can describe the processes of mechanical and chemical digestion that break down food to release nutrients, including the role of enzymes.

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Lesson details

Key learning points

  1. The differences between mechanical and chemical digestion and where they take place.
  2. Food is made up of carbohydrates, proteins and fats.
  3. Carbohydrates, proteins and fats in food are broken down by digestion into smaller molecules that can be absorbed.
  4. Enzymes are biological molecules that act as catalysts to speed up chemical digestion of carbohydrate, protein and fat.
  5. Enzymes digest carbohydrates into starch and sugars, proteins into amino acids, and fats into fatty acids and glycerol.

Keywords

  • Digestion - Digestion is the process of breaking down large food molecules into smaller molecules that can be absorbed into the blood.

  • Enzyme - An enzyme is a biological molecule that is a catalyst that speeds up the rate of a reaction.

  • Carbohydrate - A carbohydrate is a molecule made of carbon, hydrogen and oxygen, and provides energy.

  • Protein - A protein is a molecule made of amino acids, and is used for growth and repair.

  • Fat - A fat is a molecule that is stored and used for energy.

Common misconception

Food is absorbed without being digested; or "goodness" from food is what is absorbed.

The lesson explores the roles of mechanical and chemical digestion (by enzymes) of different food types into small molecules to be absorbed.

Ask pupils to create a paperchain and then tear one segment off to provide an engaging way of modelling how enzymes digest food.
Teacher tip

Licence

This content is © Oak National Academy Limited (2024), 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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6 Questions

Q1.
What is digestion?
The process of moving food through the digestive system.
Correct answer: The process of breaking down food into nutrients
The process of releasing energy from food.
Q2.
Match the nutrient to the food source.
Correct Answer:carbohydrate,potatoes

potatoes

Correct Answer:protein,meat

meat

Correct Answer:fat,butter

butter

Q3.
Which is the correct order that food passes through the digestive system?
An image in a quiz
stomach, oesophagus, liver, small intestine, large intestine
Correct answer: mouth, oesophagus, stomach, small intestine, large intestine
oesophagus, mouth, stomach, large intestine, small intestine
mouth, oesophagus, stomach, liver, large intestine, small intestine
oesophagus, mouth, small intestine, liver, large intestine
Q4.
All the organs involved in digestion make up the __________ which breaks down food and absorbs nutrients.
Correct Answer: digestive system, Digestive system, Digestive System
Q5.
What is the role of the large intestine?
absorb water and nutrients
Correct answer: process waste and absorb water
digest food
absorb water and make fibre
Q6.
Match the digestive glands with their function.
Correct Answer:Salivary gland,Secrete digestive chemicals and add water

Secrete digestive chemicals and add water

Correct Answer:Pancreas,Secretes digestive chemicals

Secretes digestive chemicals

Correct Answer:Liver,Secretes bile

Secretes bile

6 Questions

Q1.
Grinding food, rolling food around by the tongue and churning are all examples of which type of digestion?
chemical
Correct answer: mechanical
by enzymes
Q2.
True of false? Digestion can turn soluble food into insoluble food.
True
Correct answer: False
Q3.
Which small unit are large carbohydrates like starch broken down into?
Correct Answer: sugars, Sugar, sugar, Sugars
Q4.
What are the enzymes that digest proteins called?
carbohydrases
Correct answer: proteases
lipases
Q5.
Who is right?
Jun: "Enzymes release energy from chemical reactions."
Sam: "Enzymes change chemical reactions."
Correct answer: Laura: "Enzymes speed up chemical reactions."
Q6.
In the enzyme catalysed reaction, which part is the enzyme? lactose --- lactase ---> glucose + galactose
lactose
Correct answer: lactase
glucose
galactose