Biochemical Tests for Presence of Carbohydrates, Lipids and Proteins in living Material
Materials:
Fruit juices, rice, wheat, potatoes, oil, egg albumin, Benedict’s reagent, Iodine solution, 5%
NaoH solution, 1% CuSO4 solution, test tubes, test tube holders, filter paper, burners
Procedure:
1. First of all a caution that in the experiment given below you have to deal with boiling
chemicals and fire. Be careful and make sure that:
a. You are wearing a lab coat / apron.
b. Tied up your hair.
c. While boiling a chemical, your tube’s open end is not towards you or another
person. Because if chemical boils out, it may harm you.
2. Benedict’s test: You know that the fruits juices have carbohydrates in them. Let’s test.
a. Take 2 ml of fruit juice in a test tube and add 2 ml of Benedict’s solution to it.
Now boil this solution for 2 minutes. Green precipitates that may turn orange or
red later will show the presence of carbohydrates in solution.
3. Iodine Test: Many plant materials have starch in these as this is one of the stored form of
carbohydrates in plants.
a. Take a small piece of potato and put a few drops of Iodine solution on it. Blueblack color will show the presence of starch.
b. You can do this test with rice. For that first of all extract the rice by crushing it in
water. Then take 2 ml of the extract and add a few drops of iodine. Blue-black
color will show presence of starch.
4. Biuret Test: Living materials have proteins in them and we can observe their presence by
this test.
a. In a test tube, take 5% NaoH solution and add 3 drops of 1 % CuSO4. Shake it
thoroughly.
b. In another test tube take 1 ml of albumin solution or diluted milk and add a few
drops of the above solution and boil.
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c. Pink, violet or red color will indicate the presence of proteins in the extract /
solution.
5. Test for Fats (Spot Test): Living materials also have fats in them. We can show presence
of fats by a simple spot test. Procedure is very simple as follows.
a. Take 0.5 ml of extract of peanuts or oil in a test tube.
b. Add 0.5 ml of ether in it and shake thoroughly.
c. Dip a glass rod in the solution and put its spot on a piece of filter paper.
d. Paper becomes translucent on the spot. This shows presence of fats.
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