Doc Scientia - Textbook and Workbook 1 - Natural Sciences - Grade 6 25

Unit 1: Photosynthesis

3. What conclusion can you draw after this experiment was conducted?

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Iodine solution is used as an indicator. Indicators are used to test for the presence of certain substances.

Practical task 3 Date: ...............................Practical task 3 is a class activity. This experiment will be demonstrated by your teacher.

Aim: To test for the presence of starch in different types of food.

Requirements:

• Boiled rice• Flour• Potato• Bread• Oil• Boiled egg• Cheese• Ham• Apple• Banana• Butter• Sweet potato• Two empty egg cartons/ice trays• Dropper• Iodine solution

Safety measures:Work carefully with the iodine solution and do not bring it near your face. Remember to wash your hands thoroughly afterwards, using soap and water.

Doc Scientia - Textbook and Workbook 1 - Natural Sciences - Grade 626

Life and living things

Method:

1. Place different types of food in each empty cavity of the ice tray.2. Use the dropper and drop a few drops of iodine solution on each of the different types of food.3. Observe any colour changes.

Questions:

1. How will you know which food types contain starch after the experiment?

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2. Complete the table that follows to indicate which of the following foods contain starch, and which do not. Write only yes or no in the table.

boiled rice flour potato

cheese ham unripe apple

bread oil boiled egg

Doc Scientia - Textbook and Workbook 1 - Natural Sciences - Grade 6 27

Unit 1: Photosynthesis

banana butter sweet potato

Type of food Contains starch (yes or no) Type of food Contains starch

(yes or no)

NoteMany foods that come directly from plants contain starch. Foods that come directly from animals do not contain starch.