Testing for Starch

• Is glucose soluble or insoluble?

  Soluble
• Is starch soluble or insoluble?

  Insoluble
• What do plants convert glucose into?

  Starch
• Why is glucose stored as starch?

  So it's ready for later photosynthesis
• When is starch storage particularly important for plants?

  When photosynthesis isn't happening as much
• Where is starch stored in plants?

  Roots, stems, seeds, and leaves
• Why is it better for plants to store glucose as starch?

  Starch is insoluble
• What would happen to a cell with lots of glucose inside?

  It would draw in lots of water and swell up
• What process describes water moving from high to low concentration?

  Osmosis
• What substance is used to test leaves for starch?

  Iodine
• What color does iodine turn in the presence of starch?

  Blue
• What is the first step in the given method?

  Boil leaf for 2 minutes
• Why is the leaf boiled in the first step of the method?

  To soften the leaf tissue
• After boiling, where should the leaf be placed?

  In a test tube half full of ethanol
• How long should the test tube with the leaf and ethanol be placed in hot water?

  10 minutes
• What happens to the leaf when placed in ethanol in hot water?

  The leaf decolorizes
• After the ethanol bath, where should the leaf be placed?

  Hot water
• How long should the leaf stay in hot water the second time?

  About a minute
• Where should the leaf be spread out after the hot water bath?

  On a tile
• What should the leaf be covered with on the tile?

  Iodine solution
• What does the iodine solution test for in the leaf?

  The presence of starch