✅ 5. Required Practical: Food Tests (B3)

Question 1

What is an Independant Variable

Answer 1

In Independant Variable is the variable that is altered during a scientific experiment.

Question 2

What is a Dependant Variable

Answer 2

A Dependant Varibale is the variable being tested or measured during a scientific experiment.

Question 3

Wnat is a Control Variable

Answer 3

A Control Variable is the variable that is kept the same during a scientific experiment.

Question 4

How do you test food for Starch

Answer 4

Method:
1. Place a small amount of food on the spotting tile.

2. Add a few drops of iodine solution to the food on the spotting tile.
3. Yellow-red iodine solution turns blue-black if starch is present.
4. Repeat steps 1-3 for other types of food.
5. Record the results in a results table

Question 5

How do you test for Sugar

Answer 5

Method:
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. Blue Benedict’ solution turns brick red on heating if a sugar such as glucose is present
5. Repeat steps 1-4 for other types of food
6. Record the results in a results table

Question 6

How do you test food for Lipids

Answer 6

Method:
1. Place a small amount of food into the test tube.

2. Add a few drops of ethanol to the tube
3. Shake the test tube and leave for one minute
4. Pour the solution into a test tube of water
5. Ethanol added to a solution gives a cloudy white layer if a lipid is present.
6. Repeat steps 1-5 for other types of food
7. Record the results in a results table

Question 7

How do you test for Protien

Answer 7

Method:
1. Place a small amount of food in a test tube

2. Add 1cm^3 of Biuret reagent. Alternatively, add 1cm^3 of sodium hydroxide solution and then add a few drops of copper sulphate solution
3. Blue Biuret turns purple if protein is present
4. Repeat steps 1-3 for other types of food
5. Record the results in a results table

Question 8

Equipment needed for Food Tests Practical

Answer 8

Equipment:

• A range of small pieces of different foods (e.g cheese, crips, pasta, ham, bread, boiled sweets, nuts e.c.t)
• Test tubes
• Test tube rack
• Spotting tile
• Iodine Solution
• Benedict’s Solution
• Biuret reagent of dilute sodium hydroxide solution and copper sulphate solution
• Disposable pipettes
• Filter paper
• Water bath or beakers and a supply of hot water
• Sticky labels or waterproof pen

Question 9

Health and Safety for Food Tests Practical

Answer 9

Health and Safety:

• Do not eat any of the food
• Some people may have food allergies
• Wear chemical splash-proof eye protection
• Biuret reagent (IRRITANT)
• Sodium hydroxide (IRRITANT)
• Ethanol (HIGHLY FLAMMABLE), keep away from naked flames
• Iodine solution (HARMFUL), avoid contact with skin
• Water in the water bath will be hot

(To see each setup in more detail, see Goodnotes)

Question 10

How To Display the Results

Answer 10

A Results Table should be created with 6 columns having the headings of: ‘Food’Reagent’, ‘Food group tested for’, ‘Colour before adding to food’, ‘Colour chnage if food group is present’, and ‘Result (Positive/Negative)’. Then, have as many rows as there is needed, and fill in the table based on the results that are found.