RPA 4 - food tests

What is the initial color of Benedict’s solution before testing for sugars?

• Blue

• Red

• Green

• Yellow

Which color change indicates a positive result for sugars in Benedict’s test?

• A. Blue to purple

• B. Blue to brick red

• C. Yellow to blue

• D. Green to black

What reagent is used to test for the presence of starch?

• Benedict’s solution

• Biuret reagent

• Iodine solution

• Ethanol

What color change indicates a positive starch test with iodine solution?

• Red to blue

• Orange to green

• Blue-black to yellow

• Brown to blue-black

What does Biuret reagent test for?

• Carbohydrates

• Proteins

• Lipids

• Sugars

What color change occurs in a positive Biuret test for protein?

• Blue to purple

• Red to blue

• Yellow to black

• Green to brick red

Which of the following must be done to ensure an accurate Benedict’s test?

• Leave the solution at room temperature for 2 minutes

• Boil the sample with Benedict’s solution immediately

• Heat the solution in a water bath at about 80°C for a few minutes

• Add iodine solution before heating

Which reagent is used to test for lipids?

• Benedict’s solution

• Biuret reagent

• Ethanol and water

• Iodine solution

What observation confirms the presence of lipids in the ethanol emulsion test?

• Solution turns purple

• A cloudy white emulsion forms

• The solution stays clear

• A black precipitate forms

Which food sample is most likely to give a positive result with Benedict’s solution?

• Olive oil

• Chicken

• Glucose solution

• Starch suspension