Page 69 - Biology_F5

Biology for Advanced Level Secondary Schools

Table 1.7: Biuret test for protein

Food sample to be Procedure Observation Inference
tested
Protein Prepare a solution of egg albumen A purple Protein is
colour present
Place 2 ml of egg albumen solution in a develops
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clean and dry test tube slowly

Add 2 ml of dilute sodium hydroxide
solution and mix

Then add 2 drops of 1% of copper (II)
sulphate solution and shake (No heating
is required)

Activity 1.7: Biochemical test for proteins 3. Prepare a technical report based on
scientific writing skills.
Materials

Fresh milk, test tube, test tube rack, test
tube brush, beaker, measuring cylinder, Exercise 1.13
and dropper, 1% copper (II) sulphate 1. Proteins are said to be amphoteric
solution, and dilute sodium hydroxide in nature, what is the biological
solution
importance of this?
Procedure 2. Amino acids are the organic
(a) You are provided with a beaker compounds which are the building
containing fresh milk. blocks of protein. What reaction
(b) Using the apparati and reagents allows several amino acids to
provided, design an experiment and combine and form a protein?
carry out biochemical tests to identify
the food substances present in it. 3. Form V students conducted an
(c) Tabulate your results in a usual way experiment to study the amount of
to show the procedures followed, protein in four different food samples.
observations made, and inferences The paste from each food sample
drawn. was placed in different test tubes.
Few drops of Copper (II) sulphate
Questions solution and Sodium hydroxide
1. What is the basis of the test for the solution were added to each of the
food substance(s) present in the food test tubes. The test tubes were shaken
sample provided? and then allowed to stand for a little
2. Explain the nutritional roles of the while. The observation from the
food substance(s) present in the experiment was as shown in Figure

food sample. 1.41.

Form Five Student’s Book
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