1. 27/05/2019
Food and Digestion
W Richards
Worthing High School

2. Food types Type Found in Uses Carbohydrates Fats Proteins Vitamins
27/05/2019
Type
Found in
Uses
Carbohydrates
Fats
Proteins
Vitamins
Minerals
Fibre
Water
Bread, potatoes, cereal
Energy
Cream, butter, milk, oil
A store of energy
Meat, fish, eggs
Building and repairing cells
Vegetables, cereal
Keep things “ticking over”
Meat, milk, cereal
Strong teeth etc
Fruit + veg, cereal
Keeps you regular!
Water!
75% of the body is water

3. Food tests 1
27/05/2019
To investigate what happens in digestion we need to be able to test for different foods. Here are two simple tests:
Iodine
The test for starch:
Drop some iodine onto the food. If the iodine turns BLUE/BLACK then STARCH is present.
The test for simple sugars (e..g glucose)
Boil the food with some Benedict’s solution. If an orange “precipitate” appears then the food contains simple sugars

4. Food tests 2 The test for protein:
27/05/2019
The test for protein:
Add 5cm3 of dilute sodium hydroxide followed by 5cm3 of dilute copper sulphate. If protein is present it will produce a purple colour.
The test for fats:
Shake the food with about 10cm3 of ethanol in a test tube. Pour some of the solution into a tube containing water. If fat is present the water will turn cloudy white.

5. The digestive system
27/05/2019
The whole point of digestion is to break down our food so that we can get the bits we need from it…
The main foods affected are CARBOHYDRATES – these are broken down into GLUCOSE

6. Words – blood, lipids, proteins, digestion, starch, smaller
Enzymes
27/05/2019
Enzymes are chemicals produced by the body to help _______. When they react with food they break it down into ______ pieces which can then pass into the ______:
Carbohydrase breaks _______ (a carbohydrate) down into glucose:
Protease breaks _______ down into amino acids:
Lipase breaks fats (_____) down into fatty acids and glycerol:
Words – blood, lipids, proteins, digestion, starch, smaller

7. The small intestine
27/05/2019
This is where the “small parts” are absorbed into our blood stream…
Everything else passes into the large intestine
Glucose gets absorbed into the blood