2005-03-21 17:12:19Ame.
明眼人都知是一個擺明呃錢的功課
Name: Alice
Student no: 492420642
Date: 2005/3/13
English composition
Title: Does Starch Exist in Plants?
We all know that starch comes from the plants. As you see, the starch we eat in our daily lives, which is white and most of the plants are green. But you cannot see anything white on the green plants. Where is the starch from and how does it store inside the plants? Iodine is a chemical thing that can turn starch into deep blue. We can prove by experiment that starch exists in green plants.
Before doing the experiment, we have to prepare the materials: a little plant (it must be green, only green plants can carry on the photosynthesis ), a piece of aluminum foil and cut it into a rectangular form, a bottle of iodine, a dropper, a pair of tweezers, two 250ml-flasks, an alcohol burner, a tripod.
Choose a leaf and blind it in the middle with the aluminum foil. Put the plant under the sun for 8 hours. And put the plant into a box or a place without sunshine or light. This step is very important; make sure that the plant cannot be contacted with the light, or the experiment will be failed. It will ensure that the starch is produced during the experiment. Let the plant stay there for a night. The second day put the plant under the sun again for 8 hours.
Cut the leaf which was blinded with aluminum foil off. Put it into the glass of alcohol and boil it for five minutes, until the green color, or chlorophyll fades off. Because the alcohol is the organic substance that can make the chlorophyll (also an organic substance) dissolve, so the iodine can be shown clearly. And the boiling alcohol can accelerate the dissolution of the chlorophyll. After that we need to put the leaf into the hot water to make it soft after we take it out from the alcohol. Use the tweezers to pick up the leaf and wash it with distilled water, and put it on the watch glass. Drop 6-10 drops of iodine on the leaf, and you will see the part which was covered by aluminum foil before was still yellow, and the rest part of leaf turns into deep blue.
We also take a leaf from the plant which hasn’t covered with aluminum foil, use this leaf to do the steps mentioned before as a control experiment, and finally you will find that the whole leaf turns into deep blue.
The part which turns into deep blue proves that the starch exist in the leaf. Because starch can react with iodine and turns into deep blue. And photosynthesis needs light, or sun shine to carry on a set of reactions.
好明顯，如果記得這個實驗是如何進行的都知道我在亂說。
明明要寫progress,但是在下用吹水方式寫了一個簡單到極的實驗
4月11日修改。
Student no: 492420642
Date: 2005/3/13
English composition
Title: Does Starch Exist in Plants?
We all know that starch comes from the plants. As you see, the starch we eat in our daily lives, which is white and most of the plants are green. But you cannot see anything white on the green plants. Where is the starch from and how does it store inside the plants? Iodine is a chemical thing that can turn starch into deep blue. We can prove by experiment that starch exists in green plants.
Before doing the experiment, we have to prepare the materials: a little plant (it must be green, only green plants can carry on the photosynthesis ), a piece of aluminum foil and cut it into a rectangular form, a bottle of iodine, a dropper, a pair of tweezers, two 250ml-flasks, an alcohol burner, a tripod.
Choose a leaf and blind it in the middle with the aluminum foil. Put the plant under the sun for 8 hours. And put the plant into a box or a place without sunshine or light. This step is very important; make sure that the plant cannot be contacted with the light, or the experiment will be failed. It will ensure that the starch is produced during the experiment. Let the plant stay there for a night. The second day put the plant under the sun again for 8 hours.
Cut the leaf which was blinded with aluminum foil off. Put it into the glass of alcohol and boil it for five minutes, until the green color, or chlorophyll fades off. Because the alcohol is the organic substance that can make the chlorophyll (also an organic substance) dissolve, so the iodine can be shown clearly. And the boiling alcohol can accelerate the dissolution of the chlorophyll. After that we need to put the leaf into the hot water to make it soft after we take it out from the alcohol. Use the tweezers to pick up the leaf and wash it with distilled water, and put it on the watch glass. Drop 6-10 drops of iodine on the leaf, and you will see the part which was covered by aluminum foil before was still yellow, and the rest part of leaf turns into deep blue.
We also take a leaf from the plant which hasn’t covered with aluminum foil, use this leaf to do the steps mentioned before as a control experiment, and finally you will find that the whole leaf turns into deep blue.
The part which turns into deep blue proves that the starch exist in the leaf. Because starch can react with iodine and turns into deep blue. And photosynthesis needs light, or sun shine to carry on a set of reactions.
好明顯，如果記得這個實驗是如何進行的都知道我在亂說。
明明要寫progress,但是在下用吹水方式寫了一個簡單到極的實驗
4月11日修改。