Food and Digestion

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Food and Digestion
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Food types
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
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Food tests 1
To investigate what happens in digestion we need
to be able to test for different foods. Here are
two simple tests

• 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 Benedicts solution. If
  an orange precipitate appears then the food
  contains simple sugars

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Food tests 2

• 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.

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The digestive system
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
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Enzymes
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
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The small intestine
This is where the small parts are absorbed into
our blood stream