Required Practical Activity 4 - Use qualitative reagents to test for a range of carbohydrates, lipids, and proteins Flashcards Preview

AQA GCSE Biology > Required Practical Activity 4 - Use qualitative reagents to test for a range of carbohydrates, lipids, and proteins > Flashcards

Flashcards in Required Practical Activity 4 - Use qualitative reagents to test for a range of carbohydrates, lipids, and proteins Deck (9)
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1
Q

What is the apparatus needed to use qualitative reagents to test for a range of carbohydrates, lipids, and proteins?

A
  • Food: potato, carrot, crisps, biscuits, cheese
  • Spotting tile
  • Pipette
  • 10cm3 measuring cylinder or plastic syringe
  • Beaker
  • Boiling tubes
  • Heating equipment
  • Test tubes
  • Iodine solution
  • Benedict’s reagent
  • Ethanol
2
Q

What is the method used to test for starch?

A
  1. Put a small piece of the food to test on a white tile.
  2. Add two drops of iodine solution to the food.
  3. If the iodine goes from orange-brown to blue-black, the food contains starch.
3
Q

What is the method used to test for glucose?

A
  1. Mix a small sample of the food with 3 cm3 of Benedict’s solution in a boiling tube.
  2. Heat the mixture in a hot water bath for 3 minutes.
  3. If the solution goes from blue to brick red colour, the food contains sugar.
4
Q

What is the method used to test for protein?

A
  1. Mix a small sample of the food with 3 cm³ of biuret solution.
  2. Leave for 2 minutes.
  3. If the mixture goes from blue to a pale purple colour, the food contains protein.
5
Q

What is the method used to test for lipids?

A
  1. Mix a small sample of the food with 1 cm of ethanol in a dry test tube.
  2. Pour the ethanol into a test tube full of cold water.
  3. If the water goes from colourless to milky white, the food contains lipid.
6
Q

What is the colour change for positive starch test?

A

Orange/brown - blue/black

7
Q

What is the colour change for positive glucose test?

A

Blue to brick red

8
Q

What is the colour change for positive protein test?

A

Blue to lilac/purple

9
Q

What is the colour change for a positive lipid test?

A

Colourless - cloudy white precipitate

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