1. Testing for Biochemicals
Gr C: Explain how to do test for different molecules in food.
Gr B: Analyse contents of different solutions.
Gr A: Write a practical report
Entrance Activity
Draw an image of the following pieces of lab equipment:
Pipette, test tube, spatula, flask
Measuring cylinder, beaker
Key Learning Terms
Biochemical test
Iodine Solution
Benedict’s reagent
Biuret reagent

2. Quick Check Questions 10mins Learning Activity
Name the four organic molecules found in humans.
What is an organic molecule?
Draw a fat molecule and label the fatty acid and glycerol.
Explain what hydrolysis is.
What are the two types of carbohydrates?
Extension Activity
6) Compare the hydrolysis chemical reaction with the condensation chemical reaction.

3. Check your Equipment
Test tube tack containing 3 different solutions (Starch solution, glucose solution, Egg white (Protein).
Iodine Solution
Benedict’s Solution
Biuret Reagent
3 Pipettes
Goggles for each individual in your team.
Learning Activity
Your task is to find out what colours each biochemical test changes too when mixed with either: Protein; Glucose; Starch.
You need to complete eac of the tables on the following slide.

4. Positive Biuret Reagent Test Positive Benedict’s Reagent Test
Experiment
Solution tests
Biuret Reagent (Used to test for Protein)
Positive Biuret Reagent Test
Start Colour:
Final Colour:
Clear Blue
Purple
Iodine Solution (Used to test for Starch)
Positive Iodine Test
Start Colour:
Final Colour:
Straw Yellow
Blue/Black
Benedict’s reagent (Used to test for Glucose)
Positive Benedict’s Reagent Test
Start Colour:
Final Colour:
Clear Blue
Orange

5. “Whiteboard Challenge”
What is the biochemical found in the solution?
Protein

6. “Whiteboard Challenge”
What is the chemical test used in this experiment?
Iodine test

7. “Whiteboard Challenge”
What is the chemical test used in this experiment?
Benedict’s Solution

8. “Whiteboard Challenge”
What is the colour is biuret reagent before it is mixed with protein?

9. Testing for Biochemicals
Gr C: Explain how to do test for different molecules in food.
Gr B: Analyse contents of different solutions.
Gr A: Write a practical report
Entrance Activity
Draw an image of the following pieces of lab equipment:
Pipette, test tube, spatula, flask
Measuring cylinder, beaker
Key Learning Terms
Biochemical test
Iodine Solution
Benedict’s reagent
Biuret reagent

10. Colour after testing with each regent. Iodine Solution
Mr Helps’ Results
Analyse the results below and write down the contents of each solution.
Solution
Colour after testing with each regent.
Iodine Solution
Benedict’s Reagent
Biuret reagent
Contents A
Blue-black
Clear Blue B
Straw Yellow
Orange
Purple C
Clear blue D
Blue-Black
Faint purple E
Suggest, giving your reasons, which of these solutions might be:
Milk
Washing water
Sweetened Tea
Urine from someone with diabetes
Potato Solution

11. Colour after testing with each regent. Iodine Solution
Mr Helps’ Results
Analyse the results below and write down the contents of each solution.
Solution
Colour after testing with each regent.
Iodine Solution
Benedict’s Reagent
Biuret reagent
Contents A
Blue-black
Clear Blue
Starch B
Straw Yellow
Orange
Purple
Protein and Glucose (lactose) C
Clear blue
None D
Blue-Black
Faint purple
Protein, glucose and starch E
Glucose

12. Colour after testing with each regent. Iodine Solution
Mr Helps’ Results
Analyse the results below and write down the contents of each solution.
Solution
Colour after testing with each regent.
Iodine Solution
Benedict’s Reagent
Biuret reagent
Contents A
Blue-black
Clear Blue
Washing powder B
Straw Yellow
Orange
Purple
Milk C
Clear blue
Tea D
Blue-Black
Faint purple
Potato E
Urine
Suggest, giving your reasons, which of these solutions might be:
Milk
Washing water
Sweetened Tea
Urine from someone with diabetes
Potato Solution

13. Testing for Biochemicals
Gr C: Explain how to do test for different molecules in food.
Gr B: Analyse contents of different solutions.
Gr A: Write a practical report
Entrance Activity
Draw an image of the following pieces of lab equipment:
Pipette, test tube, spatula, flask
Measuring cylinder, beaker
Key Learning Terms
Biochemical test
Iodine Solution
Benedict’s reagent
Biuret reagent

14. Lab Report Learning Activity Home Learning
Create a lab report for the 3 experiments we have done in class today. The report should explain the whole experiment and give enough detail for someone to carry out the same experiment. The requirements for the lab report are listed below:
Introduction
(What is the purpose of the test?)
Equipment List
(What equipment was used and why?)
Method
(Step by step list of instructions)
Results table
(Table displaying your results)
Conclusion
(A paragraph explaining your results)
Extension task
Write down a list of variables that need to be controlled during this experiment and explain why they need to be controlled.
Due Date
One weeks time

15. Testing for Biochemicals
Gr C: Explain how to do test for different molecules in food.
Gr B: Analyse contents of different solutions.
Gr A: Write a practical report
Entrance Activity
Draw an image of the following pieces of lab equipment:
Pipette, test tube, spatula, flask
Measuring cylinder, beaker
Key Learning Terms
Biochemical test
Iodine Solution
Benedict’s reagent
Biuret reagent

16. Plenary
Learning Activity
When making comparisons between different solutions it is important to carry out all tests under the same conditions. What factors do you think are important to keep the same?
Test should be done on equal volumes of unknown solution.
Equal volumes of test solution should also be used.
All mixtures should be kept at the same temperature.
Chemicals should be left for the same amount of time.
If stirring is used, the same amount of stirring needs to take place in each solution.