Food Tests

Question 1

Answer 1

Question 2

Answer 2

Benedict’s turns brick-red /1 mark)
Biuret - turns purple /1 mark)

Question 3

What is the test for lipids

Answer 3

Question 4

What is the test for proteins?

Answer 4

biuret solution

Question 5

What is the test for starch?

Answer 5

Iodine solution

Question 6

Answer 6

Blue to brick red

Question 7

Answer 7

Browny- orange to
Black/ blue black

Question 8

Method – testing amylase at different pH

Answer 8

Take 2 spotting tiles and place 2 drops of iodine solution in all the dimples
Label a test tube with the pH to be tested.
Use the syringe to place 2 cm3 of amylase into the test tube.
Add 1 cm3 of your pH buffer solution to the test tube using a pipette.
Use another clean syringe to add 2 cm3 of starch to the amylase/ buffer solution. Mix using your plastic pipette. Start the stop clock and leave it on throughout the test.
After 20 seconds, use the plastic pipette to place one drop of your test tube mixture into the first drop of iodine. The iodine solution should turn blue-black. Squirt the rest of the solution in the pipette back into the test tube.
After another 20 seconds remove a second drop of the mixture and add it to the next drop of iodine.
Repeat step 7 until the iodine solution and the amylase/ buffer/ starch mixture remain orange.
Count up how many dimples in the spotting tile you have used, each one equals 20 seconds of reaction time.
Record this time in a results table
Repeat the whole procedure 1-10 two more times
Calculate an average.

Question 9

What must you do to Benedict solution when testing for glucose?

Answer 9

Heat it (normally using a water bath to 80 degrees C)