explain the test of starch with an example
Answers
Explanation:
According to the observation the food sample or the potato slice turned to blue-black on adding the iodine solution. This proves the presence of starch in the given plant source. This was a simple experiment which is used to check for the presence of starch
Starch is a white, powdery substance consisting of glucose which is used by plants as food.
Materials required-
- Fresh green leaf
- Around 250ml of water
- A boiling pot
- A test tube
- Ethanol
- Iodine solution.
Procedure-
To begin with, you should boil the water first and then place the leaf into it for two minutes. After that, remove the leaf from there and place it in a test tube containing 90% ethanol. Now, boil this solution for 10 minutes and rinse the leaf in cold water afterwards.
After that, place this leaf on a clean tile and add a few drops of iodine solution. If it turns blue-black, it contains starch.
Observation-Alcohol breaks down the chlorophyll and hot water kills the leaf. Hence, the leaf is no more green in color When leaves are treated with iodine, one of them turns its colour to blue-black due to the presence of starch with iodine as an indicator. The other leaf turns its colour to reddish-brown.
Conclusion-
The leaf that was kept in light turns blue-black in colour indicating the leaf has been carrying out photosynthesis, producing starch.