Fehling Solution and Starch Test Experiment

Tests for Biomolecules

• Test for Sucrose: Add a small amount of Benedicts solution to a test tube, then add a few drops of sugar solution. Heat the mixture, and a red or orange precipitate will form, indicating the presence of sucrose.

• Test for Glucose: Mix 5cc of grape juice with 2cc of Fehling's solution in a test tube. Heat the mixture, and a red or orange precipitate will form, indicating the presence of glucose.

• Test for Starch: Mix a small amount of starch (e.g., from potatoes, rice, or wheat) with water to create a paste. Add a few drops of iodine solution, and a blue color will appear, indicating the presence of starch.

Protein Tests

• Xanthoproteic Test: Add a small amount of concentrated nitric acid to a test tube, and a white color will appear. Heat the mixture, and a yellow color will form. Then, add ammonia and heat again, and the color will change to orange, indicating the presence of protein.

• Biuret Test: Mix a small amount of sodium hydroxide and copper sulfate solution with a protein sample. Heat the mixture, and a purple color will appear, indicating the presence of protein.

• Millon's Test: Add a small amount of mercuric sulfate and nitric acid to a test tube, then add a few drops of protein solution. Heat the mixture, and a red color will appear, indicating the presence of protein.

Fat and Oil Tests

• Sudan III Test: Mix a small amount of fat or oil with Sudan III solution. A red color will appear, indicating the presence of fat or oil.

• Millon's Test: Add a small amount of mercuric sulfate and nitric acid to a test tube, then add a few drops of fat or oil. Heat the mixture, and a red color will appear, indicating the presence of fat or oil.

Preparation of Acetone Extract of Leaves

• Grind 10g of fresh spinach leaves with 40ml of 80% acetone and a small amount of calcium carbonate. Filter the mixture, and the resulting dark-colored liquid is the acetone extract of leaves, which contains chloroplast pigments.

Importance of Biomolecules

• Carbohydrates, fats, and proteins are essential biomolecules for the human body.

• Carbohydrates and fats provide energy for the body.

• Proteins are essential for the growth and repair of cells.