a) For the simple sugars, if the contents in the testtube have turned into a yellow/orange colour then one has achieved a positive result. For the starches, if the food sample turns black after dropping an iodine solution on it, one has a positive result. Finally, for the fats, if a grease spot occur after rubbing the food sample on the paper, then one has a positive result.
2. Starch molecules are large carbohydrate polymers. Find and post an image of the molecular structure of starch. What are the building blocks that starch molecules are made of?
3. Thomas and Josh had interesting results to their simple sugar test - if you are following either of their blogs, look at their picture of their test tubes after they took them out of the hot water bath.
After 2 minutes, only 2 of the test tubes were yellow/orange, and the rest remained blue. They took the two positive test tubes out of the hot water bath and left the others in the hot water bath for 2 more minutes. At the end of the two extra minutes all the test tubes indicated a positive result. Based on your knowledge of carbohydrate molecules, why do you think they got these results?
a) Carbohydrate molecules are made up of glucose molecules, so when the carbohydrates are heated up they break down and become glucose giving a positive result in the simple sugar test.
4. Making connections - Describe the passage of one of your food items through the digestive system, starting with the mouth & ending at the anus. Include the specific enzymes, accessory organ secretions & internal conditions the food/chyme would pass through from start to finish.
a) For a bagel the digestion starts in the mouth with the salivary glands which will produce salivary amylase to break down the starch to maltose. Once the bagel begins to travel down the esophagus through peristalsis, the bagel has now become a food ball called a bolus. It then goes into the stomach, through the cardiac sphincter, where gastric juice turns the bolus into chyme. After the stomach the chyme is sent into the small intestine, through the pyloric sphincter, where the digestion of starch continues, the pancreas excretes out pancreatic amylase which breaks down starches into maltose. After all the starch has turned into maltose the small intestine has an enzyme called maltase to break down the maltose into glucose. It is then absorbed into the body for energy, goes through the large intestine turning into feces, goes into the rectum and is collected and then comes out the anus.
