Salam (May Allah Bless You). I am sorry guys I haven’t posted in a month and more but I was having my Cambridge Examination of Biology and today was the last exam, so I can post now. Today I have brought to you the last part of Biology for O-level Cambridge as the rest have been written. You can check those out on my homepage.
- Add a spatula measure of starch solution in boiling tube. To test with a food just crush, grind and ground the food in water.
- Pour a few drops of Iodine Solution and stir the mixture.
- Notice the color of the liquid change. The iodine solution is an orange colored solution which changes to Blue Black in the presence of starch but in the absence of starch it does not change color.
Reducing Sugar Test
- Reducing Sugars are monosacharide carbohydrates, such as glucose. Pour a 5 cm^3 of glucose solution in a boiling tube. To test with a food just crush, grind and ground the food in water.
- Prepare a water bath using a bunsen burner, a beaker and fill the beaker with water. Stir the water to evenly distribute the heat.
- Place the boiling tube in the water bath and pour a few drops of Benedict’s Reagent.
- Let the solution boil. Mix the content of the boiling tube to ensure even distribution of the reagent.
- Notice the color change from blue to green to yellow to orange to red. The color changes according to the concentration of the reducing sugar. Blue means no reducing sugar is present, green indicates traces of the reducing sugar, yellow has a slightly positive result while orange and red show the most concentration of reducing sugar.
- To test with a food just crush, grind and ground the food in water. Add the food in a dry boiling tube. You can use cheese or oil or any other lipid.
- Add 3 cm^3 of ethanol in the boiling tube.
- Mix the contents and add 2 cm^3 water in the boiling tube and notice the bubbles forming.
- You will notice that the solution emulsifies.
- To test with a food just crush, grind and ground the food in water. Add the content in boiling tube. Use a boiled egg white as it contains the protein albumin.
- Add 3cm^3 of water and mix it well.
- Add a few drops of biuret reagent and mix it well.
- Notice the color change. The biuret reagent is blue in color but changes to lilac color/violet in the presence of protein.
This marks the end of Biology and from tomorrow I will write on Physics and Chemistry. The way these will be written is in the same pattern as before for maximum understanding. I will try my best to provide you with the best information with the easiest of ways to understand. Thank You for viewing and take care.