What do we need to digest our food? L.I: To understand the major food groups our bodies need to digest and to carry out food tests THINK: What is digestion? What do we need to digest our food?

The digestive system Food must be digested before our bodies can use it. DIGESTION means breaking down large, insoluble molecules of food into smaller, soluble molecules. This takes place in our digestive system, which runs from the mouth to the anus.

Carbohydrates - are energy foods Fats – store energy Proteins – used for growth and repair Vitamins & Minerals – keep our bodies healthy Fibre – keeps food moving through our system

Substance Chemical test Result Sugar Solution Starch Solution When the Benedict's reagent was placed in the sugar solution and heated it turned _____. Starch Solution When the Iodine was placed into the starch solution it turned _____ ______. Protein solution When the Biuret solution was placed into the protein solution it turned ________. Fat – Method 1 When the butter was rubbed on the filter paper, the paper became translucent as a ______ _____ appeared on the paper. Fat – Method 2 When the cheese was placed into the water and ethanol solution, the test tube became _____. Benedict’s solution Iodine Biuret Solution Translucent Fat Test Water and Ethanol

Testing for Starch You will need: iodine solution, starch solution, test tube and a test tube rack . Fill one quarter (¼) of a test tube with starch solution. Add a few (3- 4) drops of iodine into the test tube. (WARNING: THIS MAY STAIN SO AVOID SPILLAGES) Record on your worksheet using the words provided what colour the solution in the test tube turns. Pour the iodine down the sink. Wash away any excess black liquid that is in the sink as it will stain.

Testing for Protein You will need: Biuret solution, protein solution, test tube and a test tube rack . Fill one quarter (¼) of a test tube with protein solution. Add a few drops (3 - 4) of Biuret solution into the test tube. (WARNING: THIS MAY STAIN). Shake the test tube and leave for 2 minutes. Record on your worksheet using the words provided what colour the solution in the test tube turns.

Fat method 1 – Translucent spot test You will need: 1 sheet of filter paper, 1 small cube of butter and 1 paper towel Collect the butter in a paper towel using a spatula and bring back to your desk. Using your fingers, rub the butter into the filter paper. Hold the paper up the light, and record on your worksheet in your table what has happened to the paper.

Substance Chemical test Result Sugar Solution Starch Solution When the Benedict's reagent was placed in the sugar solution and heated it turned _____. Starch Solution When the Iodine was placed into the starch solution it turned _____ ______. Protein solution When the Biuret solution was placed into the protein solution it turned ________. Fat – Method 1 When the butter was rubbed on the filter paper, the paper became translucent as a ______ _____ appeared on the paper. Fat – Method 2 When the cheese was placed into the water and ethanol solution, the test tube became _____. Benedict’s solution orange Iodine blue black Biuret Solution lilac Translucent Fat Test clear spot Water and Ethanol cloudy

4 food samples were tested can you identify what food group they belong too? IODINE BIRUET SOLUTION BENEDICT’S SOLUTION TRANSLUCENT SPOT TEST WATER & ETHANOL A B C D

Can you identify the food group? Sample A could contain __________ because Iodine test showed positive results. Sample B could contain __________ because the Benedict’s reagent shows positive results. Sample C could contain__________ because the Biuret solution showed positive results. Sample D could contain __________ because both the translucent and water and ethanol test showed positive results. starch sugar protein fat

What you have learnt today. I can name the major food groups and explain why we need them. I know the tests used to carry out food tests.