1. Food Test & Enzymes
B1b(2)

2. OBJECTIVES
Identify what carbohydrates, proteins and fats are made up of
Explain what happens during chemical digestion
Identify which enzymes break down which food types

3. I can carry out simple food tests
Can-do task
2 points

4. Method

5. Results Food sample Test Chemicals used Treatment Result if present
Our result
potato
starch
(carbohydrate)
iodine solution
add
blue/black
sweet drink
(glucose)
simple sugar
Benedict’s solution
add then heat
orange precipitate
egg white
protein
few drops of 10% sodium hydroxide solution, then
few drops of 1% copper(II) sulfate solution
rose pink or purple
cooking oil
fats and oils
paper
translucent mark (lets light through when dry)

6. I can carry out an experiment on enzyme action and record the results and conclusion
Can-do task
3 points

7. Method
While you are waiting for the experiment to finish, complete Q13-17 on page 21 in the orange text book

8. Results and Conclusion
To get the marks you must have written a conclusion based on your results.
You need to:
Describe what happened
What this means (i.e. what does amylase do?)
Amylase is found in the mouth so;
What types of food will it work on as you are chewing?
How will you know it is working (what would you taste?)

9. What are carbohydrates?
Starchy foods contain carbohydrates which are made of long chains of identical small sugar molecules.
carbohydratemolecule
one sugar molecule
The long chains of carbohydrates are broken down into the smaller sugar molecules by the body.
The small molecules from carbohydrates are used by the body to release energy and make the body work.

10. What are proteins?
Proteins, like carbohydrates, are made of long chains of small molecules. In proteins, these small molecules are
not identical.
protein
molecule
one
amino acid
Proteins are made up of chains of small molecules called amino acids. There are over 20 different kinds of amino acid.
Proteins are used by the body for growth and repair.

11. What are fats?
Fats are made up of fat molecules which contain fatty acids and glycerol.
fat
molecule
fatty acids
glycerol
Fat molecules have to be broken down by the body so that they can be used for energy storage.
Fats are also used by the body to keep heat in and to make cell membranes.

12. What happens to food so we can digest it?
Chemicals called enzymes act to break down food into smaller pieces so we can absorb them – a process called CHEMICAL DIGESTION.
There are specific enzymes for specific foods:
Carbohydrates are broken down by carbohydrases
Proteins are broken down by proteases
Fats (also known as lipids) are broken down by lipases

13. long carbohydrate molecule
Carbohydrates are chains of identical sugar molecules.
The digestive enzymes called carbohydrases break the chemical bonds between the individual sugar molecules in each carbohydrate chain.
carbohydrase
long carbohydrate molecule
sugar
molecules

14. long protein molecule amino acid molecules
Proteins are made up of amino acids. There are 20 different types of amino acids.
Proteins are digested by digestive enzymes called proteases. These enzymes work in an acidic environment to break proteins into smaller amino acids.
protease
long
protein molecule
amino acid molecules

15. + bile lipase fat molecule fatty acids glycerol
Fats are digested in two stages:
Firstly, bile (released by the gall bladder) allows the fat to “mix” with water by breaking the fat into smaller droplets. This is called emulsification.
bile
Secondly, the digestive enzyme lipase breaks each fat molecule into the smaller glycerol fatty acid molecules . +
lipase
fat molecule
fatty acids
glycerol

16. At what temperature does this enzyme work best?

17. OBJECTIVES What are carbohydrates, fats & proteins made up of?
Carbohydrates - simple sugars such as glucose
fats - fatty acids and glycerol
proteins - amino acids
What happens in chemical digestion?
the digestive enzymes break down large food molecules into smaller ones for absorption into the blood plasma or lymph
Which enzymes break down the different food groups?
Carbohydrates - carbohydrases
Fats - lipases
Proteins - proteases