CHLOROPHYLL

• EFFECT OF CHLOROPHYLL

  • The effect of the presence or absence of chlorophyll on photosynthesis can be investigated using a variegated plant.
  • Variegated plants have regions of their leaves with, and without, chlorophyll.
  • Only those areas of the leaf with chlorophyll photosynthesise. They will test positive for starch, which is built up from the glucose produced.
• EFFECT OF CHLOROPHYLL

  One way of testing for starch on a leaf is to remove the chlorophyll and then stain it to see where the starch had been stored.

  1. The leaf of a variegated Pelargonium is dropped in boiling water to kill and preserve it.
  2. The leaf is left for 10 minutes in hot ethanol in a boiling tube. This removes the chlorophyll.
  3. The leaf is dipped in boiling water to soften it.
  4. The leaf is spread out in a Petri dish and covered with iodine solution.
  5. The areas that had the chlorophyll stain blue-black. The areas that had no chlorophyll remain pale.
• EFFECT OF CHLOROPHYLL

  Risks:

  Care must be taken when using boiling ethanol.

  Make sure that no Bunsen burners are turned on as the ethanol is highly flammable