Biology Required Practical - Food Tests

Question 1

What is the aim of the investigation?

Answer 1

We will test foods, to investigate, if they contain carbohydrates [ simple sugars or starch] , lipids or proteins.

Question 2

Safety precautions to carry out in this investigation:

Answer 2

1. Do not eat any of the food
2. Be aware of those who have food allergies.
3. Wear chemical, splash-proof eye protection.
4. Biuret reagent and sodium hydroxide are both irritant to the skin
5. Ethanol is highly flammable
6. Iodine solution is extremely harmful towards the skin, so avoid contact.
7. Water bath’s water will be hot.

Question 3

Equipment needed for this practical:

Answer 3

1. A range of small pieces of different food [ cheese, chip, pasta, ham, bread, boiled sweets]
2. Test tubes
3. Test-tube rack
4. Spotting tile
5. Iodine solution
6. Benedict’s solution
7. Biuret reagent
8. Disposable pipettes
9. Filter paper
10. Water bath
11. Sticky labels

Question 4

Method: Testing for starch

Answer 4

1. Place a small amount of food on the spotting tile.
2. Add a few drops of the iodine solution to the spotting tile.
3. If starch is present, solution turns black.

Question 5

Method: Test for sugar

Answer 5

1. Place a small amount of food in a test tube
2. Add enough Benedict’s solution to cover the food.
3. Place the test tube in a warm water bath for 10 minutes.
4. If sugar is present, colour turns brick-red.

Question 6

Method: Test for lipids

Answer 6

1. Place a small amount of food into a test tube
2. Add a few drops of ethanol to the test tube.
3. Shake the test tube and leave it for a minute

4 Pour the solution into a test tube oft water.

5. If lipid is present, a cloudy white layer will form.

Question 7

Method: Test for protein

Answer 7

1. Place a small amount of food in a test tube.
2. Add 1cm^3 of Biuret reagent.
3. If protein is present, this solution will turn purple

Question 8

Test for sugar

Answer 8

Benedict test

Question 9

Test for starch

Answer 9

Iodine Test

Question 10

Test for lipids

Answer 10

Ethanol

Question 11

Test for protein

Answer 11

Biuret reagent