Question 31
Investigate digestion in the mouth
Some foods such as bread and rice contain a substance called starch. We can tell if a food contains starch by testing it with iodine solution. The starch makes the iodine solution change colour from yellow-brown to blue-black.
You will need: bread, an iodine solution, two saucers, a dropper, a spoon.
Do not drop iodine onto your clothes. It will stain them. Do not taste or swallow any iodine as it is harmful.
1. Put a small piece of bread on the saucer. Add a drop of iodine solution.
2. Place a small piece of bread in your mouth and chew it. Keep it in your mouth without swallowing it for about three minutes. Does the taste of the bread change? If so, how does it change?
3. Take the bread out of your mouth with the spoon and put the bread on the other clean saucer. Add a drop of iodine solution.
Editorial safety note: work with teacher/adult supervision and clean separate equipment. Only fresh untreated bread goes in the mouth; never eat bread after adding iodine. Do not share chewed bread or utensils. Check food allergies, wash hands and avoid splashes. Record your own observations, which may differ from the expected examples.
5a Make a conclusion for the investigation.
Some foods such as bread and rice contain a substance called starch. We can tell if a food contains starch by testing it with iodine solution. The starch makes the iodine solution change colour from yellow-brown to blue-black.
You will need: bread, an iodine solution, two saucers, a dropper, a spoon.
Do not drop iodine onto your clothes. It will stain them. Do not taste or swallow any iodine as it is harmful.
1. Put a small piece of bread on the saucer. Add a drop of iodine solution.
2. Place a small piece of bread in your mouth and chew it. Keep it in your mouth without swallowing it for about three minutes. Does the taste of the bread change? If so, how does it change?
3. Take the bread out of your mouth with the spoon and put the bread on the other clean saucer. Add a drop of iodine solution.
Editorial safety note: work with teacher/adult supervision and clean separate equipment. Only fresh untreated bread goes in the mouth; never eat bread after adding iodine. Do not share chewed bread or utensils. Check food allergies, wash hands and avoid splashes. Record your own observations, which may differ from the expected examples.
5a Make a conclusion for the investigation.
