SATHEE: Exemplar Problems

Biology Problems

Exemplar Problems

Question:

Find out a qualitative test for proteins, fats and oils, amino acids and test any fruit juice, saliva, sweat and urine for them

Answer:

Qualitative tests can be conducted to detect the presence of proteins, fats and oils, and amino acids in various substances, including fruit juice, saliva, sweat, and urine. Here are some commonly used qualitative tests for these biomolecules:

Test for Proteins (Biuret Test):

The Biuret test is used to detect the presence of proteins.
In this test, a few drops of a dilute copper sulfate solution are added to the sample. Then, a few drops of sodium hydroxide (NaOH) solution are added.
If proteins are present, a violet or purple color change indicates a positive result.

Test for Fats and Oils (Paper Test):

The paper test is a simple method to check for the presence of fats and oils in a substance.
A small amount of the sample is placed on a piece of filter paper. If the substance leaves a translucent or greasy mark on the paper, it suggests the presence of fats or oils.

Test for Amino Acids (Ninhydrin Test):

The Ninhydrin test is used to detect the presence of amino acids.
A few drops of a ninhydrin solution are added to the sample and heated. The ninhydrin reagent reacts with amino acids.
A positive result is indicated by the development of a purple or blue color.

To perform these tests on fruit juice, saliva, sweat, and urine:

Proteins:
- Take a small sample of the substance (e.g., fruit juice, saliva, sweat, or urine).
- Perform the Biuret test by adding a few drops of dilute copper sulfate and sodium hydroxide. Observe for a color change.
Fats and Oils:
- Apply a small amount of the substance to a piece of filter paper. Look for a translucent or greasy mark.
Amino Acids:
- Take a small sample and add ninhydrin solution. Heat the mixture and watch for a purple or blue color development.

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Engineering Preparation

Medical Preparation

NCERT Books & Solutions

Important Resources

Other Resources

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