I expect glucose in milk because in the factory sugar is added to the milk from the cow.
I expect glucose in tomatoes because it is a fruit, it is sweet but you don’t taste it.
What did we need?
To do the first starch experiment I needed:
- 2 test tubes and a test tube rack
- A marker
- Iodine solution with a drop dispenser
To do the second starch experiment I needed:
- articles of food, I used bread, potato, milk, ketchup, apple and butter.
- a knife and a saucer (to mince solid food)
- a test tube and a test tube rack
- iodine solution with a drop dispenser
To do the first glucose experiment I needed:
- 2 test tubes
- a knife or a spatula
- glucose
- 2 test strips for the demonstration of glucose
To do the second glucose experiment I needed:
- articles of food, I used apple, potato, bread, butter, ketchup and milk
- a knife and a saucer
- a test tube and a test tube rack
- test strips to demonstrate glucose.
What did we do?
The first starch experiment, Demonstration of starch, and the first glucose experiment, Demonstration of glucose, were not important. We found out in the first starch experiment that iodine is an indicative agent for starch. It means that iodine only reacts with starch.
In the first glucose experiment we found out that the test strip is an indicative agent for glucose.
The second starch experiment, Starch in articles of food.
We took an article of food and we minced it thoroughly. The food was put in the test tube and water was added. We than added two drops of iodine solution to the test tube.
We wrote the name of the article in our notebook and we also wrote down the final colour of the solution in the test tube. When the water turned dark blue/purple we knew there was starch in it.
We did the same for the other articles of food.
The second glucose experiment, Glucose in articles of food.
We took an article of food and, if necessary, we minced the article. We put an article of food into a test tube and ¾ of the length of the test tube was filled with water.
The right end of the test strip was plunged in the liquid. We wrote down the name of the article that was in the test tube and we wrote down the results and the colour of the right end of the test strip.
We did the same for the other particles of food. We did all the other articles the same way.
Observations.
First starch experiment:
We saw that the test tube that contained water and iodine turned yellow, transparent yellow.
We saw that the test tube with water, starch and iodine turned dark blue or purple.
Second starch experiment:
We saw that the test tube with the bread, water and iodine turned dark blue.
The other test tubes that contained milk, ketchup, apple and butter did nothing. They didn’t change. The tube with potato turned purple and also the tube with liver sausage and water turned dark blue.
First glucose experiment:
The test strip which measured glucose in water did nothing, but the strip which measured glucose in water turned green, which belongs to the number 150 mg/dl.
Second glucose experiment:
The strips which measured glucose in apple, tomato and ketchup and milk turned green or even dark green. The strips that measured glucose in the potato, bread and butter did not change.
Results
Below you can see all the observations in tables.
First starch experiment
Second starch experiment:
First glucose experiment:
Second glucose experiment:
Conclusion
I saw that iodine is an indicative agent for starch; it only reacts with starch.
The chemical to demonstrate starch is iodine. The purple colour emerges when iodine is added to starch.
We know that iodine is an indicative agent for starch. The colours of the materials in the test tube changed because bread is made of wheat, and liver sausage is heavily bounded. So that is why the colour changed.
The test strip which measured the glucose in water turned green. So when there is glucose in a liquid, the test strip turns green, when there is much glucose; the strip turns dark green. A test strip in normal water does not change. It only changes when there is glucose in a substance. So the test strip is an indicative agent for glucose.
Now we know that a test strip is an indicative agent for glucose. The test strip changed when it was put in a substance with water and milk, because sugar is added to the milk. The colour also changed when the strip was put in a substance with tomato or apple, because those are both fruits.
Discussion/Reasoning
The hypothesis was correct. There was some starch in bread, potato and liver sausage. They are all made of wheat except the liver sausage, which is bounded with starch.
There was some glucose in ketchup, apple, tomato and milk. They all taste sweet and sugar is added to the milk and ketchup. And because the apple and tomato are fruits.
