Why do we boil the leaf in alcohol when we are testing it for starch?
Why do we boil the leaf in alcohol when we are testing it for starch?
When a leaf is boiled in alcohol, two things happen.
Firstly, the leaf gets killed under heat, the waxy cuticle degenerates and the cell membrane loses it's power of selective permeability. This helps in rapid absorption by its cell walls and cell membrane . Making the cell membrane completely permeable helps in the complete destruction of the protein molecule called chlorophyll . What we have in hand now is a dead leaf with no green color, all set to be tested for starch.
Since the presence of starch can only be deduced by iodine, we place this leaf in the iodine solution. If the leaf turns blue black it is indicative of the presence of starch and if it turns reddish brown it means that the leaf does not have starch.
When a leaf is boiled in alcohol, two things happen.
Firstly, the leaf gets killed under heat, the waxy cuticle degenerates and the cell membrane loses it's power of selective permeability. This helps in rapid absorption by its cell walls and cell membrane . Making the cell membrane completely permeable helps in the complete destruction of the protein molecule called chlorophyll . What we have in hand now is a dead leaf with no green color, all set to be tested for starch.
Since the presence of starch can only be deduced by iodine, we place this leaf in the iodine solution. If the leaf turns blue black it is indicative of the presence of starch and if it turns reddish brown it means that the leaf does not have starch.
