When the plant is kept in sunlight the starch is formed in leaf.
The function of starch in the leaf is to provide energy for the cell for the different functions. When the starch in the plant cells degrades, carbon is released so that it can be utilized in the production of sucrose.
When iodine is added to a leaf with no starch, the leaf will remain its original color (usually green). Iodine reacts with starch molecules, turning the leaf blue-black if starch is present.
The half of the leaf that turns blue black in the iodine test for starch is the part that was exposed to light during photosynthesis. Starch is produced in the chloroplasts of plant cells as a result of photosynthesis, so the areas of the leaf that were able to photosynthesize will contain starch and react with the iodine to give a blue-black color.
Cold water is used to stop the process of photosynthesis in a leaf. This helps to fix any starch that has been produced in the leaf during the experiment. The cold water also makes the leaf more brittle, making it easier to handle during further steps of the experiment.
Starch is produced in the chloroplasts of plant cells, specifically in the stroma, which is the fluid inside the chloroplasts where various enzymes are located for starch synthesis. The process of starch production involves photosynthesis, where plants convert sunlight, water, and carbon dioxide into glucose, which is then polymerized into starch for storage.
The green areas of a variegated leaf contain starch, as they are the regions where photosynthesis occurs. Starch is produced during photosynthesis and serves as a storage form of energy for the plant.
bleaching removes the chlorophyll pigments from the leaf, making it easier to observe the starch produced during the starch test. Chlorophyll can interfere with the detection of starch as it also gives a green color to the leaf. By bleaching the leaf, we can ensure that any starch present is more visually distinguishable.
The leaf turned blue-black in the starch test because iodine forms a complex with starch molecules, resulting in the blue-black color change. This color change indicates the presence of starch in the leaf tissue.
The half of the leaf that did not contain starch was used up in the process of providing energy for the plant to continue growing and carrying out its metabolic functions. Any excess glucose produced during photosynthesis gets converted into starch and stored for later use.
When testing for starch, the leaf is boiled in alcohol to remove the chlorophyll that may mask the iodine-starch color change. If the leaf turns blue-black after applying iodine, it indicates the presence of starch. If the leaf remains discolored, it suggests that starch is absent, as the iodine did not react with any starch molecules present in the leaf.
The function of starch in the leaf is to provide energy for the cell for the different functions. When the starch in the plant cells degrades, carbon is released so that it can be utilized in the production of sucrose.
A hot bath of ethanol decolorizes the leaf by washing out the chlorophyll. If the leaf is not decolorized, you cannot see the blue-black stain that results from the iodine reacting with the starch.
When iodine is added to a leaf with no starch, the leaf will remain its original color (usually green). Iodine reacts with starch molecules, turning the leaf blue-black if starch is present.
The half of the leaf that turns blue black in the iodine test for starch is the part that was exposed to light during photosynthesis. Starch is produced in the chloroplasts of plant cells as a result of photosynthesis, so the areas of the leaf that were able to photosynthesize will contain starch and react with the iodine to give a blue-black color.
Cold water is used to stop the process of photosynthesis in a leaf. This helps to fix any starch that has been produced in the leaf during the experiment. The cold water also makes the leaf more brittle, making it easier to handle during further steps of the experiment.
Starch is produced by leaves during Photosynthesis, therefore if the leaf has not been exposed to light then it will not contain starch, and so when tested the Iodine will stay Yellow/Brown. Consequently if the leaf has been left in the light Photosynthesis will have taken place and when tested the Iodine will go Blue/Black showing that Starch is present. Hope this helps :)
The leaf turns brittle during the testing the leaf for starch because the ethanol extracts the all water content from the leaf.