Food Tests required practical Flashcards
What is the purpose of food tests in AQA GCSE Biology?
To identify the presence of specific nutrients in food samples.
Which test is used to detect the presence of reducing sugars?
Benedict’s test.
What color change indicates a positive result in Benedict’s test?
The solution changes from blue to brick red.
True or False: Iodine solution is used to test for starch.
True.
What color does iodine turn in the presence of starch?
Blue-black.
Which reagent is used to test for proteins?
Biuret reagent.
What color change occurs when Biuret reagent is added to a protein?
The solution turns purple.
What test is used to detect lipids?
Emulsion test.
In the emulsion test, what indicates the presence of lipids?
A milky white emulsion forms.
Fill in the blank: The test for _________ involves adding ethanol to the sample.
lipids.
How do you carry out Benedict’s test?
Heat the food sample with Benedict’s solution in a water bath.
What is the first step in testing for starch?
Add a few drops of iodine solution to the food sample.
What does a negative result in the Biuret test look like?
The solution remains blue.
True or False: The emulsion test can be used for both fats and oils.
True.
What type of sugar does Benedict’s test specifically detect?
Reducing sugars.
What is the main safety precaution when performing food tests?
Wear safety goggles and handle hot liquids carefully.
What equipment is commonly used in food tests?
Test tubes, pipettes, and water baths.
What is the role of water in the emulsion test?
To dissolve the sample before adding ethanol.
Fill in the blank: A positive test for reducing sugars indicates the presence of _________.
glucose or fructose.
Which food test requires cooling the sample before testing?
None; all tests are performed at room temperature or heated.
What is the main purpose of using a water bath in food tests?
To provide a consistent temperature for heating samples.
Which food test is the quickest to perform?
Iodine test for starch.
What happens if a sample contains both starch and reducing sugars?
Both tests will show positive results, with blue-black for starch and red for sugars.
True or False: You can directly mix iodine with a hot sample.
False.
What is the significance of a brick red precipitate in Benedict’s test?
It indicates a high concentration of reducing sugars.
List the four main types of nutrients tested in AQA GCSE food tests.
Carbohydrates, proteins, lipids, and vitamins.
