Test For Starch In Green Leaf PDF

Part Il Test for starch in a green leaf 1 Your teacher will give you a potted plant. The plant has been put under sunlight for several hours. Pick a green leaf from the plant. 2 Boil the leaf in water for 10 minutes. This destroys the cell membranes of the leaf cells, so that alco...

Part Il Test for starch in a green leaf 1 Your teacher will give you a potted plant. The plant has been put under sunlight for several hours. Pick a green leaf from the plant. 2 Boil the leaf in water for 10 minutes. This destroys the cell membranes of the leaf cells, so that alcohol and iodine solution (to be added later) can get into the cells. A Refer to Skill reminder 4 Alternatively, a hotplate on p. 193 for how to use a can be used to boil the Bunsen burner. leaf. lore) Wear safety spectacles! A Caution Be careful of the hot apparatus and water, 3 Turn off the Bunsen burner. Your teacher will help you move the hot beaker onto an insulating mat. 4 Fill a boiling tube with alcohol until it is one-third full. Use a pair of forceps or a glass rod to put the leaf into the boiling tube. Caution Alcohol is flammable. Use the smallest volume as far as possible. Ensure the room is well-ventilated. Use it only in the absence of naked flame. 5 Put the boiling tube into the beaker of hot water for 10 minutes. This dissolves chlorophyll from the leaf cells, so that any colour change of the leaf will not be masked” by its green colour. 4 The alcohol turns green because it dissolves the chlorophyll from the leaf cells. 6 Use a pair of forceps or a glass rod to transfer the leaf from the boiling tube to the hot water again. This removes the remaining alcohol from the leaf and makes the leaf soft. 7 Use a pair of forceps to take the leaf out of the hot water and spread it on a white tile. Record the colour of the leaf. 8 Add 10 drops of iodine solution to the leaf to test for starch. Record the colour change of the leaf. Caution lodine is harmful. Avoid contact with skin. » Steps of testing for starch in a green leaf and their purposes: Step Purpose 1 Boil the leaf in Destroy the cell membranes of the water. leaf cells. This allows alcohol and iodine solution to get into the cells. 2 Put the leaf into Dissolve chlorophyll from the leaf hot alcohol. cells so that the colour change can be observed. 3 Wash the leaf in Remove the remaining alcohol from hot water. the leaf and make the leaf soft. 4 Add iodine Test for starch. solution to the leaf,