test for starch

• method of testing a leaf for starch:

  1. (place measuring beaker onto tripod above Bunsen burner) with tweezers add the leaf to boiling water to destroy cell membranes and make the leaf more permeable
  2. (turn off flame because ethanol is highly flammable) put leaf in boiling ethanol to remove the chlorophyll so that the results of the iodine = more visible
  3. run leaf under water to soften it
  4. (with a bipet) add iodine to leaf to test for starch
• iodine test:

  • brown -> blue-black = starch
  • remains brown = no starch