Biology 20IB: Urine Analysis Lab

Purpose
To identify kidney disorders by analyzing four urine samples

Background Information
The tests that will be conducted are Benedict’s Test, Biuret test and pH.

Procedures
1. Drop three drops of each urine sample and water on spot plate.
2. Drop one drop of Biuret reagent in each sample of urine and water.
3. Record the colour changes of urine samples and water in data table.
4. Drop ten drops of each urine sample and water in different test tubes.
5. Drop a few drops of Benedict’s solution in each test tube with urine samples and water inside.
6. Turn on hot plate.

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7. Place beaker with water inside on hot plate and wait for water to start boiling.

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8. Once water is boiling, place all five test tubes inside the beaker.

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9. Wait two minutes.

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10. Remove test tubes from beaker and observe the colour changes of the urine samples and

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Variables
Controlled Variables - amount of urine used for tests, amount of Benedict’s solution and Biuret
reagent used for tests, amount of time test tubes were placed in water
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Manipulated Variables - different urine samples

Responding Variables - colour changes of urine samples after tests

Observations
pH and Colour Changes of Urine Samples After Benedict’s Test and Biuret Test
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Urine Sample Colour pH Benedict’s Biuret

W Clear/Pale Yellow 6 Orange Blue

X Neon Yellow 6 Clear Green Green

Y Clear 5 Clear Light Blue Blue

Z Sand Yellow 6 Clear Brown Purple

Water Clear 7 Clear Light Blue Blue

Analysis
1. I suspect that sample X has diabetes mellitus because through the Benedict’s Test, the sample

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 underwent a colour change and resulted as a green colour, which indicates the presence of
glucose in that sample.
2. I suspect that sample Y has diabetes insipidus because diabetes insipidus is a condition where
the urine contains an excess amount of water, sample Y is a clear colour, which indicates that
the urine in sample Y contains more water than the other samples.
3. I suspect that sample Z has Bright’s disease because after conducting the Biuret test, the urine
sample changed colours to purple, this indicates that protein is present in this sample, which
tells us that the subject of this sample possibly suffers from Bright’s disease because of the
malfunctions of the kidney that allow proteins to be filtered into the filtrate.
4. I suspect that the subject of sample Z has lost a tremendous amount of body water while
exercising because the initial colour of the urine in sample Z is a very dark shade of yellow,
which could indicate that there’s not a great amount of water in sample Z.
5. We used water as a control because water does not change the colour of Benedict’s solution or
biuret solution, therefore water can be used to compare the colours with each of the samples
after each test.
6. Each kidney is made up of millions of tiny nephrons because nephrons are the functional units

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of a kidney, which helps to filter the blood that enters each nephron. Millions of these

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functional units exist in each kidney because they help to increase the surface area and allows

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the filtration process to be more efficient.

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7. Three materials that are normally found in urine of a healthy person include water, nitrogen

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wastes, hydrogen ions.
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Conclusion
In this lab, we tested different samples of urine, with each urine sample coming from a
subject with some kind of kidney disorder. We identified the different kidney disorders through the
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conduction of Benedict’s Test, Biuret Test and using pH paper to test the pH of each sample. We were
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able to identify the different kidney disorders using our pre-existing knowledge of Benedict’s
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solution, Biuret solution, and what can be indicated by the initial colour of urine. We already knew
that Benedict’s solution is used to determine whether or not glucose is present in a sample, in the
presence of glucose, the blue solution changes to green, yellow, or red, depending on the amount of
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glucose present. We also knew that Biuret reagent changed colour from blue to pink or purple in the
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presence of peptide bonds (protein). Using our pre-existing knowledge, we were able to determine
that the subjects of samples X, Y, and Z had the kidney disorders of diabetes mellitus, diabetes
insipidus, and Bright’s Disease (nephritis), respectively.
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Reference(s)
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Biology 20 IB: Urine Analysis Lab

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