Why is it necessary to treat the leaf with alcohol before testing the presence of starch using iodine?
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Answered by
27
Hi Mate !!
Q. Why is it necessary to treat the leaf with alcohol before testing the presence of starch using iodine?
ans :- We boil the leaf with alcohol to remove the green color " Chlorophyll " !! And to get satisfy result !! It is important to decolorised the leaf because the Chlorophyll present on the leaf can change it's color as blue - black on adding Iodine. And we will not get the satisfied result !!
Q. Why is it necessary to treat the leaf with alcohol before testing the presence of starch using iodine?
ans :- We boil the leaf with alcohol to remove the green color " Chlorophyll " !! And to get satisfy result !! It is important to decolorised the leaf because the Chlorophyll present on the leaf can change it's color as blue - black on adding Iodine. And we will not get the satisfied result !!
Answered by
19
HELLO THERE!
Why is it necessary to treat the leaf with alcohol before testing the presence of starch?
First of all, the leaf needs to be destarched (by placing it in a dark cupboard for 24-48 hours), so that after getting positive results in the Starch test, we can say that the starch thus formed is as a result of photosynthesis.
Second, the leaf is boiled in water. This kills the living cells of the leaf.
Now, in the third step, the leaf is boiled with alcohol over a water bath (as alcohol is highly inflammable). Why is this done?
Answer: This is done to kill the green pigment, chlorophyll, in the cells. If chlorophyll is present during the starch test, we may not get the satisfactory result because chlorophyll turns the whole leaf blue black in presence of iodine (even the areas where starch is absent).
After this is done, the leaf is tested for starch. Iodine solution with a little Potassium iodide mixed with it is used. The lead is dipped in the solution.
Indication: The portions where starch is present turns blue-black whereas the portion where starch is absent turns brown.
HOPE MY ANSWER IS SATISFACTORY....
THANKS!
Why is it necessary to treat the leaf with alcohol before testing the presence of starch?
First of all, the leaf needs to be destarched (by placing it in a dark cupboard for 24-48 hours), so that after getting positive results in the Starch test, we can say that the starch thus formed is as a result of photosynthesis.
Second, the leaf is boiled in water. This kills the living cells of the leaf.
Now, in the third step, the leaf is boiled with alcohol over a water bath (as alcohol is highly inflammable). Why is this done?
Answer: This is done to kill the green pigment, chlorophyll, in the cells. If chlorophyll is present during the starch test, we may not get the satisfactory result because chlorophyll turns the whole leaf blue black in presence of iodine (even the areas where starch is absent).
After this is done, the leaf is tested for starch. Iodine solution with a little Potassium iodide mixed with it is used. The lead is dipped in the solution.
Indication: The portions where starch is present turns blue-black whereas the portion where starch is absent turns brown.
HOPE MY ANSWER IS SATISFACTORY....
THANKS!
SUCCESS123:
Thanks for answering.
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