5. Lack of a nutrient can lead to a deficiency disease, e.g. anaemia is caused by a lack of iron. Research a deficiency disease caused by one of the nutrients in the table above: • Name the disease. • Name the nutrient deficiency that causes this disease. • Describe the symptoms of this disease. • Describe the treatment for this disease.
EXPERIMENTAL INVESTIGATION 10.1 How can we investigate if starch is present in food?
Equipment 4 test tubes Dropper Test tube rack
Suggested substances to test Iodine solution Water Bread
Milk Vegetable oil
Method 1. Label four test tubes as follows: ‘Water (control)’, ‘Bread’, ‘Milk’, ‘Vegetable oil’. 2. Add 2 cm3
food to the appropriately labelled test tube. 3. Add 2–3 drops of iodine to each test tube. Swirl carefully for 5–10 seconds.
4. Stand all four test tubes in a test tube rack and observe any colour changes. A positive test for starch will show a colour change to blue-black.
5. Record your results.
SAFETY • Do not eat any of the food being tested.
of water to the test tube labelled ‘Water (control)’ and then add 2 cm3
of the correct
)Fig. 10.5 Iodine reacts with starch by turning blue-black
j Go to page 24 of your Experimental Investigations Log to write up this investigation.