Biology LC - Iodoform Test

To Prepare experiment

1. Add 20 g glucose to 200 mL water in a conical flask

2. Boil for 5 minutes to remove oxygen

3. Cover with a layer of cooking oil

4. Place flask in 30 °C water bath

5. Keep on heating tray to maintain temperature → leave overnight

Testing for Alcohol

• Add 3 mL of solution to test tube

• Add 3 mL potassium iodide + 3 mL sodium hypochlorite (brown/orange)

• Warm in 60 °C water bath for 5 minutes

• Let cool

• Yellow crystals = alcohol present

Control

• set up apparatus without yeast cells

• limewater is clear and no yellow crystals appear

Results

• limewater turns milky indicating presence of carbon dioxide

• iodoform test shows the prsence of alcohool

What is meant by the term anaerobic

no oxygen present

what other substance is produced in animal cells as result of anaerobic respiration

lactic acid

importance of keeping yeast cells at an optimum temperature

prevents denaturation

explain why alcohol production usually stops