Grade 10
LIFE SCIENCES
Date: _____________
45 Marks
PRACTICAL
Food Tests 2
Examiner: T. Bell
Moderator: Z. Yaka
NAME:
PLEASE READ THE FOLLOWING LAB SAFTELY INSTRUCTIONS CAREFULLY
1. Write your name in the block above
2. You are to work in groups of no more than 3 individuals
3. Make sure to read the INFORMATION SHEET given, as this provides vital
information for you to complete your practical
4. Experiments are carried out in a group, however, each individual will hand in a
separate report.
Assessment criteria
Ability to follow
instruction
Ability to observe safely
precautions
Ability to work tidily
Tidies up afterwards
Organization – work
through procedure in
orderly manner
Ability to use apparatus
or equipment
Performance levels
0
1
Unable to follow
Instructions followed
instructions
with supervision
Unable to observe safety Sometimes careless with
precautions
safety precautions
Cannot work tidily
Can work tidily
Does not tidy up or help
Has to be reminded to
to clean
tidy up
Disorganized
Relatively organized
Apparatus always used
incorrectly
Apparatus sometimes
used correctly
2
Able to work on own
Follows safety
precautions
Tidies up without
reminding
Very organized
Apparatus always used
correctly
TOTALS:
PRACTICAL SKILLS
/10
INVESTIGATION A
/18
INVESTIGATION B
/17
TOTAL
/45
Page 1 of 5
FOOD TEST
LIPIDS AND PROTEINS
Page 2 of 5
INVESTIGATION 1: TEST FOR LIPIDS
PART A - Investigation
Before you begin, make sure that you have all of the materials at your work bench:

Ethanol

Small piece of biscuit

Two test tubes

Filter paper

2 ml peanut butter


(unglazed paper)
Lipids are fats and oils that have a greasy quality to them. If a substance contains lipids, a
translucent mark (grease spot) will be left on filter paper. If a grease spot is not present, then
the substance is not or does not contain lipids.
Instructions:
1. Label the test tubes “A” and “B”
2. Add 2 ml of peanut butter to test tube “A” and the small piece of biscuit to test tube
“B”
3. Place 2 ml ethanol into each test tube. The ethanol will dissolve any fat molecules in
the sample
4. Pour a small drop of each solution onto a sheet of filter paper
5. Let the paper dry; the ethanol will evaporate
6. Hold the paper in front of the window or light source and record your observations in
the table below
Page 3 of 5
Observations:
Lipid present
Observation
(yes/no)
Peanut butter sample
Biscuit sample
(4)
TASK 4: Testing for the Presence of Protein
To test for protein, the Biurets test is done. The Biuret reagent will change from blue to pinkpurple in the presence of proteins.
Materials:

An egg (white part only)

2 test tubes

Starch solution

Biurets solution

1 large beaker

spatula
Instructions:
1. Label the test tubes “A” and “B”
2. Add some water to the egg white and mix thoroughly
3. Pour 2 ml of the egg white solution into a test tube “A”
4. Pour 2 ml of the milk into test tube “B”
5. Add a few drops of Biuret reagent into each test tube and swirl the tubes gently
6. Note any colour changes and record these in the table below
Observations:
Observation
Protein present (yes/no)
Egg
white
Page 4 of 5
Milk
(6)
Page 5 of 5